Deep Forest Tunery [CLOSED]

[budious]

Deep Forest Tunery
by budious

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Deep Forest Raceway... a versatile track with numerous corners of varying turn radiuses and bank angles. Defining a good tune on the course can produce a nimble and plush ride that maintains traction while still hugging the track surface hard enough for the last two high speed corners. However, there is no one-fits-all solution, so adaption is the key to success. Many of our tunes will now feature multiple sub sets of suspension tweaks or other settings that will enhance the core setup across multiple courses. In addition, we now invite the public to participate and to intern under our banner by providing enhancements of their own under our new Open Intern Tuner Program guidelines.

A few differences you will notice between the other garages and the tunes I offer are that they are not necessarily the best lap time producers but provide consistent and reproducible lap times. Most of the cars I tune are low to middle range performance road cars, occasionally I offer setups for race cars but I'm more focused on the weekend track warrior tunes. The vast majority of my tunes will be equipped with tires between Sport Hard and Race Hard, that doesn't mean you can't use a softer grade, but keep in mind the harder tires need to warm up for optimal grip. However, due to our recent participation in the Tuner Challenge Championship, we have decided to expand our initial offerings to include more high-end exotics and premium race car tunes.

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Important
Please do not quote entire posts or articles in replies. Choose quotations only relevant to your reply.

Community Projects sponsored by Deep Forest Tunery
Open Tuning Initiative

Deep Forest Tunery Test Data
How to select and optimize drivetrain components, and the not so obvious effects.

 

[budious]

Open Tuning Initiative

Sponsored by Deep Forest Tunery

This article's formulae provided by budious​

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Introduction: (coming soon)

This is a work in progress and as such, it is very unpolished and somewhat disorganized at the moment. However, if you take the time to read it and understand it and comprehend my approaches to tuning you will find value in them. I aim to make this post the most comprehensive GT tuning resource to date and will continue to update and revise it until I think it is has achieved that status. Also, I want to convey the need to differentiate between the content of this OTI sponsor post as my personal approaches and the distinction I am attempting to make by launching this as a community project. I am offering my work only as a starting point to building something bigger than I can provide alone.​

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The Bigger Picture:

The goal of starting the Open Tuning Initiative is to get everyone involved. My personal goal is just to get the ball rolling. I am looking for volunteers to pursue the goals and agenda of the Open Tuning Initiative as an independent and community owned project. I highly encourage anyone with sought after skills to offer to their services to the project in addition to the other tuning garages forming similar sponsor posts in their own threads to share their experiences and tuning methods.​

• Project Manager: Experience with version control, management of code repositories, quality control.
• Forum Moderator: Public relations and primary maintainer of an official Open Tuning Initiative thread or sub-forum.
• Wiki Hosting and Maintainer: Host responsible for maintaining hosting services and domain name featuring the most up to date and generally agreed up equations and tuning methods detailed.
• Programmers: Those with programming experience willing to contribute code under an open source license and to assign copyright to the Open Tuning Initiative.
  • I have a personal preference towards Java for cross platform compatibility with JAR files; my fellow Linux and OSX users can agree.
• Data Analysts: Good at analysizing large data sets of known good results for correlations.
• Mathematicians: Statisticians to assist with data analysis and to construct and improve formulas used for tuning.
• Real World Tuning Experts: Tuning opinions based on real-world tuning principals and equations.
• GT Tuning Experts: Tuning opinions based on the behavior of the GT physics engine and resulting equations and correlations of results.

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Change Log: (new)

Adding a change log to make this post more friendly to returning readers. I won't necessarily note rewrites of sections, but I will note additions of new content or revisions to formulas, examples, and exercises.​

• 04-22-11-A: Minor correction in the denominator of the Stiffness Factor of Spring Rates for adjusting offset ride height distributions front and rear.
• 04-18-11-C: Added the alternative theory for Damping and Anti-Roll Bar Efficiency Factor from the RX-7 demonstration post to the relevant section in this post.
• 04-18-11-B: Eliminated motion ratio division from base ride height in denominator of the Stiffness Factor of Spring Rates - SF(SR) equation; this was an error since I have normalized base ride height in the numerator by dividing each spring rate by the motion ratio already. Only the ride height change needs to be compensated for in the denominator.
• 04-18-11-A: Added change log to track future updates. New RX-7 demonstration post available of these equations put into practice.

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Methodology: (coming soon)

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Terminology: (more coming soon)

• Low Speed Damping: controls slow vertical movements of the suspension components such as those caused by rolling bumps, wavy pavement, acceleration or in the case of fork springs, while making turns or braking, independent of speed.
  • Adjustments made to dampers in GT control low speed damping.
  • Low Speed Compression (LSC): LSC is affected most during cornering. LSC damping is the damping circuit in the shock absorber or fork that is tuned to provide suspension travel at low damper speed conditions. Too low of LSC damping will cause the excessive travel use, brake dive, rear end wanting to come around while braking, or bottoming out. Too high of LSC damping will cause loss of traction on small bumps.
  • Low Speed Extension (LSE): LSE is the opposite of LSC, as it affects extension. If LSE is set too low the damper will bounce or chatter over bumps, if set too high the damper will pump down on small bumps, unable to return to its sag point between bumps until it uses up all of its travel forcing the chassis to take the brunt of the bump resulting in a very abrupt "tank-slapper" movement, lose tire traction and possibly crash.
• High Speed Damping: controls fast vertical movements of suspension components caused by road characteristics such as square-edged bumps.
  • High Speed Compression (HSC): circuit in the shock absorber or suspension fork is tuned to provide suspension travel control at high speed over square-edged bumps. Too low of HSC damping will cause excessive bottoming out in rough terrain. Too high of HSC damping will minimize suspension travel in rough terrain and cause loss of traction.
  • High Speed Extension (HSE): circuit is the opposite of HSC damping, as it affects extension. A damper with too slow of a rebound setting will stay compressed after hitting a bump, and cannot rebound quickly enough to absorb the impact of a second or third bump. Properly set-up rebound dampening will prevent a shock from going past its starting point. "Pogoing", (when the rear shock rebounds so quickly that the rear wheel leaves the ground), will occur if the HSR is set too high.
• Anti-Roll Bars (Stabilizers): A stabilizer bar tries to keep the car's body flat by moving force from one side of the body to another. When you go into a turn, the front suspension member of the outside of the turn gets pushed upward. The arm of the sway bar gets pushed upward, and this applies torsion to the rod. The torsion them moves the arm at the other end of the rod, and this causes the suspension on the other side of the car to compress as well. The car's body tends to stay flat in the turn. If you don't have a stabilizer bar, you tend to have a lot of trouble with body roll in a turn. If you have too much stabilizer bar, you tend to lose independence between the suspension members on both sides of the car. When one wheel hits a bump, the stabilizer bar transmits the bump to the other side of the car as well, which is not what you want. The ideal is to find a setting that reduces body roll but does not hurt the independence of the tires.

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Formulas: (more coming soon)

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My formulas in context:

First off, my approach to tuning is from a computer science perspective and how I would expect a programmer to simplify a series of complicated real world processes into a manageable program that has most of the expected behaviors of the real thing; think of Trinity and Morpheus zooming down that freeway shootout scene in the Matrix: Reloaded... it's a complex computer program with rules that can be manipulated.

All variables play more than one role typically. Using a variable in one equation for a particular sub component or evaluation of a particular factor does not exclude or account for its purpose elsewhere in the physics engine. Formulas may represent simplified or generalized concepts that examine singular relationships and do not represent the broad picture. However, use of each and every sub equation together can produce a harmonious tune that excels on the race course. Building the larger equation to fabricate the entire tune all in one go is the difficulty that lies ahead.

Some equations are more accurate than others and represent various stages of evolution and quality in results produced. The idea here by me sharing all these is for you not to reply to my thread calling me a retard for not using Washed Up Racer X's spring rate formulas. These equations, on my part, is so that all of you can participate in Open Tuning Initiative by providing useful positive or negative feedback and to engage in open debate on how to best proceed in creating a universal tuning application. I expected many revisions along the way... perfection doesn't come overnight.​

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Brake Controller Bias

This is not an equation, but I am going to put it here because it is a fundamental element of the game and I see a lot of discussion about how to set it. I have a different view on it than most of my fellow tuners. My assumption is that if the car naturally has a stronger brake bias on the front, bigger rotors and more pistons in the caliber, then it reflects this when the brake controller is set at 5/5. You are not adjusting the ratio of braking front to rear; rather, the adjustments affect the stopping power proportional to the strength of the brake setup on a particular end of the car. For this reason, I rarely feel the need to deviate from the default setup.​

• 1 = 20%
• 2 = 40 %
• 3 = 60 %
• 4 = 80 %
• 5 = 100 %
• 6 = 120 %
• 7 = 140 %
• 8 = 160 %
• 9 = 180 %
• 10 = 200 %

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Chassis Rigidity Factor

This equation doesn't have much of a purpose on its own and is highly speculative and based entirely on conjecture made through observation of handling differences on cars in the game. There is probably a similar type equation used in the game and the resulting variable is used as a contributing factor in the master suspension tuning balance equation.​

• Chassis Rigidity Factor = (1.00 - (LN(DLR) / 100) + (CR))
  • CR (chassis reinforcement) is a conditional variable; if chassis reinforcement installed than equal to .1, else .0
  • DLR (distance from last reset) represents mileage since GT Auto chassis service.
  • Likely that there is another degree of variation in permanent chassis degradation due to overall that cannot be repaired by GT Auto. Perhaps (LN(Mileage) / 1000) should be in there as well.

Examples:

Chassis Condition of 96% at 50 miles:
= 1.00 - (LN(50)/100) + .0
= 1.00 - 0.0391202300543 + .0
= 0.960879769946
= ~ 96%

Chassis Condition of 95% at 100 miles:
= 1.00 - (LN(100)/100) + .0
= 1.00 - 0.04605170186 + .0
= 0.95394829814
= ~ 95%

Chassis Condition of 93% at 1,000 miles:
= 1.00 - (LN(1000)/100) + .0
= 1.00 - 0.06907755279+ .0
= 0.93092244721
= ~ 93%

Chassis Condition of 90% at 20,000 miles:
= 1.00 - (LN(20000)/100) + .0
= 1.00 - 0.0990348755254 + .0
= 0.900965124475
= ~ 90%

Chassis Condition of 89% at 40,000 miles:
= 1.00 - (LN(40000)/100) + .0
= 1.00 - 0.105966347331 + .0
= 0.894033652669
= ~ 89%

Chassis Condition of 99% at 40,000 miles with Chassis Reinforcement:
= 1.00 - (LN(40000)/100) + .1
= 1.00 - 0.105966347331 + .1
= 0.994033652669
= ~ 99%

​

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Supported Weight Distribution (Not Actual Weight Distribution)

This equation's purpose is to produce a proportional representation of the amount of weight supported by front and rear spring rates respectively. This can be simplified when the car uses the same motion from front to rear and the denominator becomes common and thus eliminated (FR MR; RR MR). The purpose of this particular equation becomes more obvious once I post the spring frequency, or stiffness factor, equation.​

• FR WT SUP % = (SR FR / FR MR) / ((SR FR / FR MR) + (SR RR / RR MR))
• RR WT SUP % = (SR RR / RR MR) / ((SR FR / FR MR) + (SR RR / RR MR))

• FR WT SUP % = SR FR / (SR FR + SR RR)
• RR WT SUP % = SR RR / (SR FR + SR RR)

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Stiffness Factor of Spring Rates; SF(SR):

This equation is quite possible the holy grail, and yet in some ways, the least significant. Once you tune with the damping and stabilizer equation below you'll understand why this is actually the less important half of the larger picture. The basic principle is to combine the front and rear spring rates, then divide that sum by the quotient of the car's weight divided by the cumulative ride height. That was the simplified form assuming the motion ratio is the same front to rear, for which appears to be the case for most of the cars in the game.​

• ( FR SR + RR SR ) / ( WT KG / ( Base RH + ( RH ) )

Example:
( 7.0 + 7.8 ) / ( 1480 / ( 100 + ( 0 ) )
14.8 / 14.8 = 1.00
​

The formula taking motion ratio into account uses a simplified representation for front motion ratio (FR MR) and rear motion ratio (RR MR) as a literal ratio. In other words, if a front motion ratio of 2:1 has 50mm suspension travel for 100mm wheel travel, and the rear motion ratio is 1:1 for 100mm suspension travel for 100mm wheel travel then FR MR = 2 and RR MR = 1.​

• ( ( FR SR / FR MR ) + ( RR SR / RR MR ) ) / ( WT KG / ( ( Base RH ) + ( ( ( FR RH / FR MR ) + ( RR RH / RR MR ) ) / 2 ) ) )

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Ride Height to Spring Rate Calculation (with natural frequency, or stiffness factor)

The formula here is to recalculate the spring rate's natural frequency or stiffness factor or whatever the representation generated by the formula is intended to represent is arbitrary, but it works. Finding out the base motion ratio is the tricky part but there are methods of testing that have shown good results. Fortunately, the vast majority of cars appear to use 100mm (4in) of suspension travel as their base. This literally translates to a +5mm change to ride height makes the suspension 5% stiffer, and a -5mm change to ride height makes the suspension 5% softer. For most cars, if you performed weight reductions and the car was 12% lighter afterwards, then reducing ride height by 12mm would equate the same relative spring rate. However, you must remember that ride height also determines the amount of weight transfer that occurs so setting it too low may have other unintended consequences. For this reason, I needed a way to recalculate spring rates in relation to ride height but also take into account a new stiffness factor, or sf(x).​

Simplified - motion ratios are 1:1 front to rear:

• ( FR WT SUP * WT CAR * SF(X) ) / (Base RH + (RH) )
• ( RR WT SUP * WT CAR * SF(X) ) / (Base RH + (RH) )

Less Simplified - motion ratios vary front to rear:

• ( FR WT SUP * WT CAR * SF(X) ) / ( (Base RH / FR MR) + (RH / FR MR) )
• ( RR WT SUP * WT CAR * SF(X) ) / ( (Base RH / RR MR) + (RH / RR MR) )

Practical Application(s):

• Tsukuba Circuit: Any car typically benefits from this ratio being around ~2.51, or ~1.255 depending on how it was calculated.

Other Applications(s):

• Has some relation to the damping and stabilizer efficiency balancing theory in the equation below, but also is a bit too ambiguous to plug into the calculation as is at the moment.

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Damping & Stabilizer Efficiency Balancing

A correlation can be drawn between the sum of the LOG of dampers and the natural log of the anti-roll bars; the analysis was taken from the default settings of fully customized suspension settings across a sampling of 40 cars from the game. The correlation was additionally reinforced through testing and tune development and with a few exceptions (due to other variables in a larger equation) appears to be a solid foundation for all future tuning. The idea behind the equation is that you should try to get it to equal out as close as possible to 1.00 to achieve maximum grip. Two known variables are chassis reinforcement installation status and mileage in determining the overall chassis rigidity factor of the car; typically compensating for these conditions requires plus or minus one damper from the following equation. There is also a relationship between the damper-stabilizer equation to the spring frequency, or stiffness factor; I will post more on this later. Aerodynamics also come into the equation of balance but more so on their relation to spring rate stiffness before it is factored against the damper and stabilizer balance.​

• ( LOG(Extension) + LOG(Compression) ) / LN(ARB) = Efficiency %

Dampers:

• LOG(1) = 0
• LOG(2) = 0.301
• LOG(3) = 0.477
• LOG(4) = 0.602
• LOG(5) = 0.699
• LOG(6) = 0.778
• LOG(7) = 0.845
• LOG(8) = 0.903
• LOG(9) = 0.954
• LOG(10) = 1

Anti-Roll Bars:

• LN(1) = 0
• LN(2) = 0.693
• LN(3) = 1.099
• LN(4) = 1.386
• LN(5) = 1.609
• LN(6) = 1.792
• LN(7) = 1.946

The total number required is a mathematical equation to itself, but the combination used for extension and compression create different handling qualities. Com > Ext will drive different from Ext > Com or Ext = Com.

Example:

IE. The default on many race cars is Ext 8, Com 8, ARB 6

LOG(8) + LOG (8) = 1.806179974
------------------------------------------------ = 1.00804823694 (~100% or about perfectly balanced)
LN(6) = 1.79175946923​

An alternative theory: (this rectifies problems with division of 0 or by 0 since 0^0 = 1)

Stiffness Factor of Spring Rates ^ Natural Log of Anti-Roll Bar
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Sum of the Damper LOGs ^ Natural Log of the Anti-Roll Bar

or

(SF(SR)^LN(ARB)) / (LOG(Extension) + LOG(Compression) ^ LN(ARB))​

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Limited Slip Differential Tuning (preliminary write-up)

There is usually a very small threshold between unstable corner entry and stable corner entry with LSD braking sensitivity. Most of the time I find it to be around 12-13 and occasionally a little above or below that.

As for initial and acceleration, there seem to be ratios that work well together.

1:2
1:3
1:4 (ie. initial 10 w/ accel 40)
1:5
8:7 (ie. initial: 16 w/ accel: 14; initial 24 w/ accel 21; initial 32 w/ accel 28; initial 40 w/ accel 35)
8:6

Then also some not so patterned combos like 19i:52a or 19i:60a, I'm sure there are more good pre-configured LSD combos but these are ones you can start with and get pretty good results, or fine tune in small increments away from.​

budious' pre-configured LSDs for general usage: (trial and error for car and track)

• 16/14/(12-13)
• 24/21/(12-13)
• 24/18/(12-13)
• 32/28/(12-13)
• 32/24/(12-13)
• 40/35/(12-13)
• 48/42/(12-13)
• 56/49/(12-13)
• 19/52/(12-13)
• 19/60/(12-13)
• 46/60/(?)

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Practical Examples using my Formulas: (coming soon)

Example 1-A: Adjusting weight distribution on a car with variable motion ratios:

My previously titled equations applicable to this example:

• Supported Weight Distribution (Not Actual Weight Distribution)
• Spring Rate to Weight Ratio (natural frequency; stiffness factor)
• Ride Height to Spring Rate Calculation (with natural frequency, or stiffness factor)

Here is the formula I have been working on for taking motion ratios into account, though knowing the actual motion ratios to use is kind of an arbitrary exercise at the moment. I did recall reading that one of shocks was mounted mid-arm on the Supra so I just assumed a motion ratio of 2:1 for a simple exercise.

I need to test this formula in principal across a wider base of test cars, so offer feedback with data sets you try including weight distribution and motion ratio resources you find online for the cars you attempt to apply it to.

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Toyota Supra 3.0GT Turbo A '88 - resources indicated a 53/47 weight distribution, so lets attempt to find our base spring rates before applying additional rate for transfer loads.

FR WT DIST = (SR FR / FR MR) / ((SR FR / FR MR) + (SR RR / RR MR))

RR WT DIST = (SR RR / RR MR) / ((SR FR / FR MR) + (SR RR / RR MR))

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So I have rewritten the above equation for front supported weight distribution as a formula to find front spring rate when rear spring rate equals 6.4kgf/mm.

If you got a graphing calculator: (Y = % FR WT DIST; X = FR SR; when RR SR = 6.4)

Y = (X / 2) / ((X / 2) + (6.4 / 1)

Set your window on the graph so Min X: 0; Max X: 20; Min Y: 0; Max Y: 1

You can now use the trace function to follow the curve, where Y=.530 then X=14.46

So approximating for now, but we'll round off to 14.3 or 14.4 for Front Spring Rate if Rear Spring Rate is 6.4 for the Supra. I used 14.3/6.4 in my testing and found these rates to be approximately 1-1.5" faster on Autumn Ring Mini than the stock rates in the fully customized suspension depending on the dampers used. Either this is a fluke result which is why it needs more testing, or I'm on the right track.

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Deep Forest Raceway
299HP Supra w/ Low RPM Turbo, Sport Softs, FC Suspension; everything else stock.

Stock FC Suspension
RH: 0 / 0
SR: 13.5 / 6.8
Ext: 5 / 5
Com: 5 / 5
ARB: 3 / 3
Cam: 0.0 / 0.0
Toe: 0.00 / 0.00 (zeroed for testing)

Alternative Setup A for RR SR = 6.4
RH: 0 / 0
SR: 14.3 / 6.4
Ext: 5 / 5
Com: 5 / 5
ARB: 3 / 3
Cam: 0.0 / 0.0
Toe: 0.00 / 0.00

Alternative Setup B for RR SR = 6.8:
RH: 0 / 0
SR: 15.3 / 6.8
Ext: 5 / 5
Com: 5 / 5
ARB: 3 / 3
Cam: 0.0 / 0.0
Toe: 0.00 / 0.00

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Best Lap Results (based on short 5 lap run);
Stock: 1:25.7" (least consistent lap times)
Alternative A: 1.25.5" (more consistent lap times)
Alternative B: 1.25.0" (noticeably stiffer but produced best lap)
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Example 2-A: Practical proof in the pudding - An example of spring rate to weight ratio calculation utilizing changes in ride height to re-balance the equation.

My previously titled equations applicable to this example:

• Spring Rate to Weight Ratio (natural frequency; stiffness factor)
• Ride Height to Spring Rate Calculation (with natural frequency, or stiffness factor)

To complete this exercise you are going to need to own or purchase two weight unmodified cars of the following make:

• Toyota MR2 1600 G-Limited Super Charger '86 (1070KG)
• Toyota MR2 1600 G '86 (1120KG)

These cars are nearly identical except one is the super charged variant and weighs in at 50KG less than its less equipped sibling. Use the following setup to test drive both cars; it has been tuned for the lighter G-Limited Super Charger '86 variant to run on the Nordschleife.

Ride Height: 0 / 0
Spring Rate: 11.1 / 14.8
Extension: 4 / 4
Compression: 4 / 4
Anti-Roll Bar: 2 / 2
Camber: 1.6 / 1.0
Toe: 0.00 / 0.00
Tires: Sport Medium (Front) / Sport Soft (Rear)​

You should have noticed that while the super charged variant ran firmly through the corners, the lesser sibling was softer and less controllable. However, we can rectify this difference with one minor adjustment.

Let's use the formula I have provided for determining the spring stiffness factor to gauge the basic assumption I am making about how to calculate base ride height and changes to ride height by performing an easy to test handling scenario. By changing only the ride height on the above tune, the heavier and less powerful model MR2 should handle almost identically to its super charged cousin.

First, let's find the relative difference in the weight between the two cars:

1120 / 1070 = 1.0467 (~105%)​

Next, let's identify the spring stiffness factor of the original tune and car:

(11.1 + 14.8) / (1070 / (100 + (0)))
25.9 / 10.7 = 2.421
​

Now, let's identify the spring stiffness factor of the original tune applied to heavier sibling:

(11.1 + 14.8) / (1120 / (100 + (0)))
25.9 / 11.2 = 2.3125
​

Finally, let's adjust the ride height assuming a base ride of 100 as we have, that an additional ride height adjustment of +5mm will result in a 5% stiffening of the suspension and put the spring stiffness factor on par with the lighter car.

(11.1 + 14.8) / (1120 / (100 + (+5)))
25.9 / ( 1120 / 105)
25.9 / 10.666 = 2.428
​

So all we need to do now to confirm my conjecture is to apply the adjusted tune to the lower powered, heavier sibling, and to find out if the handling is now on par or close to that from that of the lighter sibling from which the tune originated. Adjust the ride height on the MR2 1600 G '86 to +5 / +5 to compensate for the extra 50KG of weight. The difference in handling should be quite apparent and nearly on par with the super charged variant. A few subtle differences remain such as the additional lateral weight transfer but for the most part should go unnoticed. Have fun on the test track!

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Example 3-A: Optimizing suspension components for maximum grip at tire contact patch. This example is not a complete tune process but only illustrates one chain of fundamental relationships in a balanced equation.

Test Car: Mazda éfini RX-7 Type R (FD) '91

• Premium car, purchase at new car dealership.
• Equipped at stock weight with upgrades to approximately 300HP.

Additional Purchases:

• GT Auto: Oil Change
• Tune Shop: Sport Soft
• Tune Shop: Fully Customized Suspension
• Tune Shop: Low RPM Turbo
• Tune Shop: Sport Exhaust

Deep Forest Raceway Testing:

• Equip the car with all purchased parts except return to factory suspension; drive a few laps around Deep Forest while noting the handling characteristics of the car.
• Equip the car with all purchased parts including the fully customized suspension; zero out the rear positive toe, then drive a few laps around Deep Forest while noting the handling characteristics of the car.

Examining the defaults on the Fully Customized Suspension for the RX-7:

Damping: For the default values on the RX-7, both extension and compression are set to values of five. These values have multiple roles in the overall physics engine, but for the particular sub-component determining overall suspension balancing, we need to compute the LOG of each.
​

Dampers:

• LOG(1) = 0
• LOG(2) = 0.301
• LOG(3) = 0.477
• LOG(4) = 0.602
• LOG(5) = 0.699
• LOG(6) = 0.778
• LOG(7) = 0.845
• LOG(8) = 0.903
• LOG(9) = 0.954
• LOG(10) = 1

RX-7's Damping Efficiency Factor, or DEF = LOG(5) + LOG(5) = 1.398

Stabilizers: For the default values on the RX-7, the anti-roll bars are set to values of four. These values have multiple roles in the overall physics engine, but for the particular sub-component determining overall suspension balancing, we need to compute the Natural Log, or LN, of the stabilizer bar.
​

Anti-Roll Bars:

• LN(1) = 0
• LN(2) = 0.693
• LN(3) = 1.099
• LN(4) = 1.386
• LN(5) = 1.609
• LN(6) = 1.792
• LN(7) = 1.946

RX-7's Stabilizer Efficiency Factor, or SEF = LN(4) = 1.386

Spring Rates (and Ride Height): As for the defaults on all cars in the game, ride height is zeroed. The spring rates on the RX-7 default setup are 8.4 front and 6.3 rear. As all variables in the suspension setup, the following calculation is not the single condition nor only contributing factor for what the maximum spring rate should be; it is only a determination of what the minimum spring rate should be.​

RX-7's Spring Rate Stiffness Factor, or SF(SR) is calculated as follows:

(Front Spring Rate + Rear Spring Rate) / (Car's Weight KG / (Base Ride Height + Ride Height Change))

(8.4 + 6.4) / (1260/(100+0)) = 1.167

This poses a problem because the spring rate stiffness factor, or SF(SR), is below the ~1.4 threshold we are looking for. So how do we achieve a SF(SR) of 1.4? For the simple purposes of testing our theory we can start with a ride height adjustment.​

(8.4 + 6.4) / (1260/(100+(+20))) = 1.400

Perfect, our formula reveals that adding +20 ride height to the car will achieve the target SF(SR) we were looking for. Let's test it on the track, watch the tire temperature indicator to realized how much grip has been optimized on your first lap. Things will probably get a little sloppy on the second lap but settle down if you keep driving. This setup achieves the intended effect we were looking for by increasing SF(SR) to 1.4 but using this method has increased lateral weight transfer on the car with the increase in ride height.​

So how do we achieve a SF(SR) of 1.4 but closer to the normal ride height, or any desired ride height, for our car? There's an equation for that... and hopefully soon enough, an equation app for that... in the meantime, break out the calculator and some scrap paper.
​

First, we need to calculate the relative distribution of supported weight on the car's springs; this should not to be confused with the actual weight distribution of the car. This is a fairly simple process.
​

% Weight Distribution Front Springs = Front Spring Rate / (Front Spring Rate + Rear Spring Rate)

% Weight Distribution Rear Springs = Rear Spring Rate / (Front Spring Rate + Rear Spring Rate)

8.4 / (8.4 + 6.3) = .571 (57.1%)

6.3 / (8.4 + 6.3) = .429 (42.9%)

You really only need to do one to find both, simply subtract the one you do first from 1.00 to get the other. Next, you need to multiply those figures by the weight of the car to find the supported weight in kilograms on each axle.​

KG Weight Distribution Front Springs = (Front Spring Rate / (Front Spring Rate + Rear Spring Rate)) x Car's Weight

KG Weight Distribution Rear Springs = (Rear Spring Rate / (Front Spring Rate + Rear Spring Rate)) x Car's Weight

8.4 / (8.4 + 6.3) = .571 x 1260 = 720 KG = 1.00 SF(SR)

6.3 / (8.4 + 6.3) = .429 x 1260 = 540 KG = 1.00 SF(SR)

The resulting figures represent the weight supported at a spring rate stiffness factor, or SF(SR), at 1. This is because the weight you multiplied against the percentage of distribution was the car's actual weight. You could have compiled the previous step with the following step, but for comprehension it was broken down into an extra step. To bump SF(SR) up to the desired 1.4 all we need to do is multiply the previous results by the new desired factor.
​

8.4 / (8.4 + 6.3) = .571 x 1260 = 720 KG x 1.4 SF(SR) = 1008KG

6.3 / (8.4 + 6.3) = .429 x 1260 = 540 KG x 1.4 SF(SR) = 756KG

Now we are ready for the final step. We need to divide these figures by the desired ride height to determine the final spring rate at that ride height. This can be a bit frustrating to do with a standard calculator. However, there are shortcuts for a graphing calculator and I will update this post and the OTI post with these at a later date. If your standard calculator supports returning to the previous line and simply overwriting the ride height value then this following task is much easier. Note: Base Ride Height is not always 100; a few cars may have a non 1:1 motion ratio on one linkage; a few others may have non 1:1 motion ratios for both linkages (ie. Formula cars are 2:1 wheel rate to spring compression). However, for the vast majority of cars in the game, a motion ratio of 1 for front and rear, and a Base Ride Height of 100 can be safely assumed.​

Stiffness Factored Weight / (Base Ride Height + (Change in Ride Height))

720 KG x 1.4 SF(SR) = 1008KG / (100 + (+5)) = 9.6 kgf/mm

540 KG x 1.4 SF(SR) = 756KG / (100 + (+5)) = 7.2 kgf/mm

These are your new spring rates at the indicated ride height. I prefer to attempt to get these figures as close to but under a whole value to a tenth of decimal accuracy as this is the limitation of the spring rate tuning allowed in the game. I also attempt to get them with no to as little rake as possible involved because rake involves shifting weight transfer and I have not yet produced a variant on the formula to account for these other variables, among many others. Basically, what I attempt to do is divide by ride heights until I find one that will make both the front and rear at the same ride height level no less than five hundredth under or one hundredth over the next closest settable value. (ie. 12.95 - 13.01 would be set to 13.0 kgf/mm)
​

The final suspension configuration for SF(SR)=1.4 @ +5mm Ride Height is as follows:

Ride Height: +5 / +5
Spring Rate: 9.6 / 7.2
Extension: 5 / 5
Compression: 5 / 5
Anti-Roll Bars: 4 / 4

Why did this work? Let's look at the much larger, but still limited, view I have assembled so far (as theorized) for the internal functioning of the suspension balancing and grip determination mechanisms of the physics engine.
​

Stiffness Factor of Spring Rates ^ Natural Log of Anti-Roll Bar
----------------------------------------------------------------------
Sum of the Damper LOGs ^ Natural Log of the Anti-Roll Bar

or

(SF(SR)^LN(ARB)) / (LOG(Extension) + LOG(Compression) ^ LN(ARB))

1.4^1.386
---------------------
(.698+.698)^1.386

1.594
------- = 1.002 (100.2% optimized)
1.591

Now keep in mind that all this does is establish the minimum stiffness factor of spring rates, SF(SR), to be used on the car you are tuning. You can increase the final ratio anywhere above 1.000 (~100%) and the car remains drivable but there is probably another such equation to determine upper range efficiency and it is probably track specific or natural frequency of the course specific to determine the new optimization. Though, I think with the above rationalization, that the car will achieve its maximum grip efficiency while increasing the stiffness factor of spring rates beyond that threshold will continue to improve lap times in a trade off for less grip. At this point much remains speculative, I only have what works on one hand, what doesn't on another, and a whole lot at my feet I haven't gotten around to just yet.​

Final Note: If you are intending to reproduce this exercise on other cars keep in mind the following things.

• See the OTI post on the Supra example for how to deal with motion ratios if the car you are tuning uses one.
• Chassis rigidity factors into this equation somewhere; attempt with new dealership purchases without chassis reinforcement for most normalized results.
• Stiffness Factor of Spring Rates >= Damping Efficiency Factor >= Anti-Roll Bar Efficiency Factor

---------------

-----------------------------------

General Purpose Tuning Assignments and Learning Tools: (Workshop Resources by budious)

---------------

Exercise 1-A: Practical application of dampers and stabilizers for tune balancing.

You want a tuning assignment to help you learn a bit about suspension? Let's take a car that drives considerably well on its stock suspension, say go purchase the Ferrari 458 Italia, then purchase some Sport Soft tires and the Fully Customizable Suspension and nothing else for the time being.

First, reequip the stock suspension and drive a few laps on a track you are interested in tuning for. Note any qualities you like or dislike about the car. Next, reequip the full custom suspension and drive a few laps and note any qualities you like or dislike. Now, copy over the spring rates from the stock suspension to the full custom suspension and set all the dampers and stabilizers to 1s, leave the default camber if any but zero out the rear toe. Drive a few more laps and note the handling, it should be identical to the stock suspension (or actually leave the stock toe to really re-achieve the stock feel), but now you have a baseline to start tuning your custom suspension.

The idea here is that for the stock weight at the stock ride height of the car, the stock spring rates are fairly decent (6.2 FR / 7.0 RR - if I recall correctly). Your tuning assignment is to not adjust ride height or spring rates, but only to make adjustments to dampers and stabilizers and note the effects on handling and to tune the car to the track using only those three adjustments (extension, compression, anti-roll bars). This should get you on your way to tuning like a pro.

---------------

-----------------------------------

Known Exploits: (hopefully not many...)

---------------

Ballast System

• The Ballast System has a "glitch" thread contains discussion and information related to exploitation of this bug.
• The short explanation is that adding a 0KG ballast at -50 will enhance rear wheel grip while adding it at +50 will enhance front wheel grip with no weight penalty; it can also be set anywhere in the range for varying effect.
• There are those of the dissenting opinion who imply 0kg ballast is a valid option and not a "glitch" but an additional tuning tool that represents changes such as engine mounting positioning or location of the battery.

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[budious]

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[drivehard]

I like the fact you posted a tune for the online time trial. being that I already massacred my lambo, weight reduc and engine upgrades, I can't try it out. often I post in 3 different forums just to get a good setup for those time trials. I'll check out the lotus tune later tonight.

 

[budious]

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[budious]

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[budious]

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[Starfirebird]

Hey man,just wanted to let you know that i added your one man garage to my Tuning Garage Database thread. 👍

 

[budious]

Hey man,just wanted to let you know that i added your one man garage to my Tuning Garage Database thread. 👍

Thanks for adding me, looking forward to the competition.

Also, matter of good timing, the Chevrolet Corvette Convertible (C1) '54 is now available from the online used car dealership for the duration of Seasonal Event #6.

Seasonal Event #6 - Bonus Race #5 @ Indy Road is a Corvette challenge, while my tune wasn't designed with that track in mind, I did find sticking Race Soft and setting FC transmission @ 180MPH got me 4th place on first try without cutting the course. If you want to play dirty you can probably finish 1st by cutting the course.

 

[drivehard]

This seems like the best place to ask. Any help with the tune for the Lutecia Renault Sport Trophy Race Car for the Rome Time Trial would be greatly appreciated. Right now I'm running:

Downforce: Max/30
Transmission: 149 mph
LSD: 7/15/9
Ride Height: -40/-40
Springs: 14.5/16.0
Dampers(Ext): 5/7
Dampers(Com) 5/6
Anti-Roll Bars: 3/4

Camber: 2.5/1.5
Toe 0.07/-0.13

Brakes: 4/6

Currently at 63rd with a 1:16.888. the leader is at 1:14.605. Right now its hard to see anything below 1:16 being possilble. Thanks in advance.

 

[budious]

This seems like the best place to ask. Any help with the tune for the Lutecia Renault Sport Trophy Race Car for the Rome Time Trial would be greatly appreciated. Right now I'm running:

...

Currently at 63rd with a 1:16.888. the leader is at 1:14.605. Right now its hard to see anything below 1:16 being possilble. Thanks in advance.

I'd love to help you but I haven't acquired this car yet. I have the Clio Renault Sport Trophy Race Car but it had already been engine overhauled and thus over the limit, I may let Bob run it for a while tonight to get it back under HP limit.

---

On other topics, Seasonal Event #6, Ferrari 430 Scuderia '07 at Monza event, I found adding Weight Reduction 3, Window Modification, Carbon Hood, Front Aero, and Rear Aero (areo @ 15/40) while keeping everything else stock was a nice balance for this race without taking too much of the fun out of it with an overpowered setup. Finished only 0.6 seconds ahead of second place car. May use this as the basis for a Spec I tune with custom suspension for a later tune, but the default suspension is pretty good on this car.

 

[drivehard]

If I see one in the UCD I'll buy it and send it to you. Thanks anyway.

 

[budious]

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[budious]

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[budious]

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[budious]

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[CCR_BR2]

Hi budious ,

if you can help me would be much appreciated, as I said I love cars with low hp, nothing against super cars

Below is a short list of cars that I can not tune up at all, some do not make a curve, other skid at the exit of it too

if you can help thank you very much

-Fiat 500 1.2 8v '08 SS
-Mazda Sport Demo '03
-1100 Standard Beetle-type-11 - '49
-Mini Cooper 1.3i '98
-Toyota Celica XX - 2800 gt '81
-Spit Fire 1500-'74 Triumph
-The Alpine-110 1600 s '73
- Ford Ka ´01
- Isuzu - Piazza Xe '81
- Lotus Elan S1 '62-
- Honda-City-turbo III '83
-Mitsubishi Colt - 1.5 x Sport - version '02
- Nissan X-Cube - (FF / CVT) '02
-BMW turbo-2002-'73

Do not hurry, answer when possible, if you can post the link on the page thank you

https://www.gtplanet.net/forum/showthread.php?t=172860

CCR_BR2

 

[budious]

I tried the Isuzu with the time trial specs, but within it's class I found it rather limited and gave up on it early on, I may revisit it again. The Alpine I tinkered with some time back but probably needs some more attention. I have been meaning to get around to the Lotus '62 and Honda '83 for a while but haven't just yet. The BMW '73 is one I have tinkered with since day one, I get it about 90% satisfactory to taste but not quite the way I want to call it finished, but I'll look to put some finishing touches on it soon.

 

[budious]

Deep Forest Tunery Test Data

How to select and optimize drivetrain components, and the not so obvious effects.

by budious​

Do you think your drivetrain is already optimized? If I had one guess at your car, I'd say it's equipped with a twin-plate clutch and semi-race flywheel, but if this is the the case, then you should think again. So now you're probably thinking, "so why would the best 'not be the best'?"

This is the current issue plaguing many tuners between their offline and online tunes, so let's clear up that misconception first. There is nothing different with the physics between the two modes, there is only one difference, circumference of your tires is no longer constant; therefore, problems that currently exist in your "offline" tune are simply obscured by residing on the threshold between being noticable and being a non-factor. Once tire wear is factored into the equation, the physics engine starts showing you where your tune is wrong. It's not in the suspension, it's not in the aerodynamics, it's not in the tire grade, it's not in the power plant, nor the weight of the car - it's simply the drivetrain.

Let's theorize as to why this is, first and foremost, clutching. How is that relevant to playing with a dualshock 3 with automatic shifting? The game is handling the emulation of the driver shift for you within the physics engine, the snap of the clutch engagement can be measured under the right test conditions. The purpose of this guide is to provide a walk through and demonstration of the testing process, how to identify common symptoms, and optimization of your drivetrain.

Let's begin by identifying the primary drivetrain components and their function, and how that function is implemented (theoretically) within the Gran Turismo 5 racing engine. The following details and exploration will give you a new appreciation for the attention to details polyphony digital went to in designing the new engine. No wonder my PS3 fan keeps kicking on, the cell processor is working overtime.

Clutches couple the engines power to the drive shaft or differential. In all clutches, friction exists to one degree or another, providing a transitional state between engagement and disengagement. A measure of a clutch's worth is the amount of friction that can be transferred. Performance designed single plate clutches offer a step up in friction offering from stock models, more elaborate models such as the double plate transfer even more.

Unfortunately, if the friction exceeds the capacity of the engine to deliver additional torque any performance gains are negligible, but detrimental effects on handling become apparent also immediately.

Why would too much friction inhibit the car's handling ability? If the driver disengages the clutch entering a corner to downshift, the following re-engagement of an engine idling at high rpms will send torque straight to the wheels, even if no throttle is being applied. The effect once transfered to the drivetrain can be mitigated by a high acceleration value on the LSD. (see symptoms - snapping)

Why a higher acceleration value? Locking the rear wheels together means both wheels are moved by the idle engagement torque; a lower value will cause the torque to be transfered to the side of least resistance, ala the dreaded snap.

Since the idling speed of an engine is influenced by the flywheel equipped, choosing the correct flywheel becomes part of the overall equation, higher idle is not necessarily better.

Symptoms of clutch engagement being counter productive can also include lurching in which a sudden change in acceleration or deceleration becomes apparent. Lurches are most noticeable in transitions between extreme acceleration or deceleration. A lurch on acceleration will be apparent when driver goes full throttle on corner exit from a previous state of coasting or deceleration; the car will suddenly lunge forward.

The opposite occurs following a release from full throttle to no throttle; the sudden transition will result in rapid deceleration caused by the engagement of the drivetrain to the now idling or dropping off of engine rpm's before the clutch finishes fully disengaging, a result of too much friction. This will be more pronounced on engines equipped with lightweight flywheels.

Each of these symptoms can be detrimental to the driving experience of your tune. Compounded, they present even more significant driving anomalies.

In the supplemental test case and test car specifications, a combination of a semi-race flywheel coupled to a LSD with an acceleration value of 30 displayed tendencies towards extreme and sudden direction changes, veering for the purposes of my terminology to differentiate it from snapping. Raising the acceleration value to 50 mitigated many of these behaviors, but introduced complexities of it's own. Veering often occurs under prolonged acceleration at full throttle during which a small surface irregularity can disrupt traction.

Running a high LSD acceleration value will cause the car to run wide as it accelerates through corners; however, somewhat contrary to the implication of running a lightweight flywheel, utilizing the combination of a semi-race flywheel with an LSD acceleration value of 50, a car can power oversteer its way through corners; whereas, when paired with a stock flywheel it would just run wide into the barrier or grass. For purposes of this guide, I refer to this behavior or running wide as snagging, hence, you'll be all over a wall.

In regards to the other extreme of LSD acceleration, a value too low will often result in spinning as the car looses traction in the corner, the torque is transferred down the path of least resistance and thus begins to spin. Spinning can be counteracted by raising LSD acceleration and/or downgrading the flywheel.

The test car displayed a pertinacity for popping wheelies at the crest of the hill exiting the first hairpin on Deep Forest Raceway when equipped with single-plate or twin-plate clutches. The effect is intensified through pairing with an upgraded flywheel.

Surging is evident on the test car when equipped with a twin-plate clutch and upgraded flywheel. Surging would best be described as tapping the brake or short braking; except, upon release the clutch is re-engaged before the engine has had time to idle down and a sudden burst of speed is experienced mid-corner or on corner exit without deliberate throttle application.

Barreling is evident on the test car when equipped with a single-plate or twin-plate clutch, an upgraded flywheel, and an LSD acceleration value of 50. Barreling is an extreme form of snapping that could be characterized as having the feel of Skid Recovery Force with an exception that there is only a 50/50 chance that it will be in the direction that you wanted to go.

Carbon drive shafts, while the demonstrated test scenarios and test car do not utilize it (mid-engine), I did test it on my Chevrolet Corvette Convertible (C3) '69 Seasonal Event 6 Spec in comparison to the stock drivetrain, it shaved almost two full seconds off of lap time alone in place of the standard drive shaft while using stock clutch and stock flywheel; there was considerable improvement in both acceleration and deceleration.

Symptoms and Remedies Recap

• Snapping is caused by having a low LSD acceleration value set in combination with a lightweight flywheel upgrade, the sudden engagement of the clutch can trigger a direction shift. When combined with an upgraded clutch a more extreme form emerges, see Barreling.
  
• Lurching becomes most apparent during extreme transitions of acceleration to deceleration, or from deceleration to acceleration. Acceleration lurches result from sudden torque application through an upgraded clutch that provides more friction than the stock component. This will be more pronounced on engines equipped with lightweight flywheels. Deceleration lurches are the sudden transitions to rapid deceleration from the engagement of the drivetrain to the now idling or dropping off of engine rpm's before the clutch finishes fully disengaging, a result of too much friction. This will be more pronounced on engines equipped with lightweight flywheels.
  
• Jerking is a prerequisite behavior to veering but without the complete loss of control. Jerking (and likewise, veering) often occurs under prolonged acceleration at full throttle during which a small surface irregularity can disrupt traction.
  
• Veering results from a combination of a semi-race flywheel coupled to a LSD with an acceleration value set too low. Raising the acceleration value to 50 mitigated many of these behaviors, but introduced complexities of it's own. Veering often occurs under prolonged acceleration at full throttle during which a small surface irregularity can disrupt traction.
  
• Snagging is a unique situation resulting from too high an LSD acceleration value combined with an stock flywheel. Running a high LSD acceleration value will cause the car to run wide as it accelerates through corners; however, somewhat contrary to the implication of running a lightweight flywheel, utilizing the combination of a semi-race flywheel with an LSD acceleration value of 50, a car can power oversteer its way through corners; whereas, when paired with a stock flywheel it would just run wide into the barrier or grass.
  
• Spinning is the counter action of snagging. An LSD acceleration value set too low will often result in spinning as the car looses traction in the corner, the torque is transferred down the path of least resistance and thus begins to spin. Spinning can be counteracted by raising LSD acceleration and/or downgrading the flywheel.
  
• Wheelies is a behavior which may be displayed on the crest of hills when cars are equipped with upgrade clutches. An upgraded flywheel will intensify this effect.
  
• Surging would best be described as tapping the brake or short braking; except, upon release the clutch is re-engaged before the engine has had time to idle down and a sudden burst of speed is experience mid-corner or on corner exit without deliberate throttle application. Surging is most evident on cars equipped with upgraded clutches and flywheels.
  
• Barreling is an extreme form of snapping that could be characterized as having the feel of Skid Recovery Force with an exception that there is only a 50/50 chance that it will be in the direction that you wanted to go. Barreling is most evident on cars with upgraded clutches and flywheels and an LSD acceleration value set too high. (50 in these test cases)

Test Briefing and the Deep Forest Driving Experience

The following scenarios were tested using the Lotus Elise 111R Test Spec which you can find below. I strongly urge you to invest the 300k credits to build it; reading this guide is not enough, you must experience it first hand to recognize these behaviors on your tunes. Test Spec utilizes the Chassis Reinforcement, the extra rigidity makes these imperfections all the more obvious. If you like the car, I suggest you build another without Chassis Reinforcement for an every day racer.

I strongly advise that your first drive with the car be on stock transmission; stock clutch; stock flywheel; LSD @ 12/30/16; until such time as you are comfortable with it and ready to begin test scenarios.

The testing scenarios were from an initial batch and thus limited in complexity. I opted for Race Soft since only the most violent of imperfections would be noticeable due to their enhanced grip; also, I wanted it to be a friendly test car scenario for a wide range of readers who may want to give this a try for themselves. I plan to do further testing scenarios utilizing Sport Softs and the Sports flywheel as a follow up to this piece.

Each of the test scenarios was run twice; two sets of five laps for each scenario on Deep Forest Raceway while either in offline practice mode or grinding A-spec. Notes were taken, some lap times were recorded just for comparison, I approximated a generalization of lap performance in parenthesis after each test data remark. The times are not indicative of best performer, just as a simple metric for those who want to quickly browse over the data.

Notice: February 5, 2011 - Tests and observations performed by me were using DualShock3 and AT shifting. I am requesting feedback from sequential shifting wheel users, as well as from those with H-pattern and clutch pedal setups, to run through these scenarios as well and to report back with your findings.

TCS off
ASM off
SRF off
ABS 1

Test Scenarios and Recorded Observations

1. Stock Clutch; Stock Flywheel; LSD @ 12/30/16; Race Soft
   • Smooth and consistent feel; but measurably lower average lap times. (1:15")
2. Stock Clutch; Semi-Race Flywheel; LSD @ 12/30/16; Race Soft
   • Snappy, prone to sudden veering, jerking, corner spin on cold Race Softs but good after first lap. (1:13.5")
3. Stock Clutch; Stock Flywheel; LSD @ 12/50/16; Race Soft
   • Runs wide in corners, snagging a real danger. Lurching present upon full throttle or release from full throttle. (1:14")
4. Stock Clutch; Semi-Race Flywheel; LSD @ 12/50/16; Race Soft
   • Capable of power oversteer to counteract snagging; better performing than scenario 3. (1:13.5")
5. Single Plate; Stock Flywheel; LSD @ 12/30/16; Race Soft
   • Smooth and consistent feel; slight wheelie on crest. (1:13.5")
6. Single Plate; Semi-Race Flywheel; LSD @ 12/30/16; Race Soft
   • Pops wheelies at crest; clutch engagement snap evident. (1:14")
7. Single Plate; Stock Flywheel; LSD @ 12/50/16; Race Soft
   • Pops wheelies at crest; smoother cornering than scenario 6; runs wider in turns; milder clutch engagement. (1:13.5")
8. Single Plate; Semi-Race Flywheel; LSD @ 12/50/16; Race Soft
   • Smooth and consistent; a touch of barreling present; great off the line grid start first lap time, three consecutive 1:13" laps ran. (1:13")
9. Twin Plate; Stock Flywheel; LSD @ 12/30/16; Race Soft
   • Smooth; but clutch engagement more noticeable over single plate. (1:13.5")
10. Twin Plate; Semi-Race Flywheel; LSD @ 12/30/16; Race Soft
    • Smooth acceleration; strong desire to wheelie crest; prone to sudden snaps; erratic in corner radius diameters - snagging; jerking over irregularities on track surface; lurching evident. (1:14")
11. Twin Plate; Stock Flywheel; LSD @ 12/50/16; Race Soft
    • Smooth and consistent feel; but measurably lower lap time. (1:14.5")
12. Twin Plate; Semi-Race Flywheel; LSD @ 12/50/16; Race Soft
    • Smooth; some wheelies at crest; erratic snapping. (1:14")
13. Stock Clutch; Sport Flywheel; LSD @ 12/30/16; Race Soft
    • Smooth and consistent, clean laps; respectable lap times. (1:12.8")
14. Stock Clutch; Sport Flywheel; LSD @ 12/50/16; Race Soft
    • Smooth and consistent, clean laps; runs a tad bit wider in corners, but power oversteer to counter. Corner entry deceleration is smooth, full throttle exit smooth. (1:12.9")
15. Single Plate; Sport Flywheel; LSD @ 12/30/16; Race Soft
    • Smooth for the most part; a bit of wheelie; a small bit of snapping. (1:12.8")
16. Single Plate; Sport Flywheel; LSD @ 12/50/16; Race Soft
    • Smooth and consistent, clean laps; good torque to friction balance; perfect power oversteer; excellent corner entry deceleration and full throttle exits are smooth. (1:12.5")
17. Twin Plate; Sport Flywheel; LSD @ 12/30/16; Race Soft
    • Smooth and consistent, clean laps; clutch engagement is more noticeable at disengage/engage at high speeds; some gentle veering is present. (1:12.8")
18. Twin Plate; Sport Flywheel; LSD @ 12/50/16; Race Soft
    • Smooth and consistent, clean laps; has the quickest first lap time from grid start of the tested combinations; runs consistently in the low 1:13's"; full throttle works most of track but occasionally need to back off, recovery is quick. (1:13.1")

Conclusions and Summary

February 2, 2011 - I have completed the additional testing scenarios for Sports flywheel and added them above (13-18). The results from those were quite interesting, the test spec car handled exceptionally well on all configurations will the Sports flywheel and put up respectable lap times during each scenario, several new lap records were made.

The main culprit of the initial wild handling of this car can be solely attributed to the Semi-Race flywheel. The high-idle spin of the flywheel appears to the source of the sudden and violent reactions this car has to clutch engagements. While some of this behavior can be mitigated by clutch selection and use of an high acceleration value on the LSD, results consistently showed that the Sports flywheel produced better lap times and far better handling.

The clutch is almost a non-factor on this car, there were a few distinct differences but the driving was consistent among scenarios 14, 16, and 18 that I repeated each for three sets of five laps just to be sure the differences were reproducible and yet minimal. The stock clutch allowed the driver to freely use full throttle for almost the entirety of the race course; it put up a respectable 1:12.8" lap time with LSD acceleration at 30, but also another at 1:12.9" with LSD acceleration at 50.

The single plate clutch displayed a slightly more apparent disengagement and re-engagement at high rpm's, but impact on handling was minimal. A small tendency towards occasional snapping was present when used with an LSD acceleration of 30, but mitigated by setting the value to 50. The single plate when paired with the Sports flywheel and an LSD acceleration of 50 proved itself to be a consistent performer, repeatedly dishing out laps in the low 1:13's and setting an highly impressive 1:12.479" best lap time (best of all tested scenarios so far). Single plate clutch proved itself as the best clutch option for this particular car.

That is not to say that the twin plate clutch did not earn an honorable mention, it displayed it's own unique characteristics. The clutch disengagement to re-engagement was a bit stronger than on the single plate, but did not prove overly detrimental to handling when paired with a Sports flywheel as it did when paired with the Semi-Race flywheel. The slight bit of veering that was produced was mitigated by raising LSD acceleration to 50. Wheelies were only slightly noticeable at crests when paired with the Sports flywheel. Lap times were consistent, typically running in the low 1:13's" and a best lap of 1:21.8" was set with LSD acceleration at 30. The best lap time from stationary grid start was set at 1:19.618" when using an LSD acceleration of 50, making this the best first lap option, this scenario repeatedly demonstrated consecutive laps in the low 1:13's but could not make it under the 1:12.999" benchmark (15 laps were ran), but for lap consistency this combination proved itself truly unique.

The last variable of the drivetrain optimization testing scenarios also seems to be a critical element. LSD acceleration repeatedly proved itself to be a valuable tool in mitigating unwanted snapping and veering associated with use of upgraded clutches and flywheels. While only two values were used for our testing purposes, testing clearly indicated that higher LSD acceleration settings tend to fair better in overall stability of the drivetrain, as well as produce higher lap times. There were some cases where the value being set too high could cause the car to run wide in corners, and this was most noticeable when paired with the stock flywheel, when paired with the Sports flywheel a well balanced and natural amount of power oversteer made sharp cornering possible. Under several of these scenarios using LSD acceleration of 50, I was not dropping below 127MPH at the apex of the last downhill bend to the straight away finish on Deep Forest Raceway without touching grass. Another unusual aspect of having LSD acceleration set to 50 was that straight line deceleration appeared to be much greater than with the value set to 30, this could just be a placebo effect, but I will do more testing to try and verify this aspect of it; upon passing the apex, it also made full throttle acceleration out of the hairpins very smooth and linear.

Based on the results I have seen already, I would not hesitate to crown test scenario 16 as the ultimate setup. The match of single clutch, sport flywheel, a LSD acceleration at 50 proved itself repeatedly with lap times and offered unrivaled handling during cornering, braking, and acceleration.

I will continue to test these setups further now that I have identified the top contenders using Race Softs; the next phase will be to test the finalists on Sport Softs.

Revisiting my theory on clutching being present in the simulation of drivetrain performance, my initial suspicion appears to be reaffirmed. My theory would be that the clutch shift interval (CSi) is present, and that each clutch upgrade fills this duration with a wider range of friction values.

Forgive the crudity of the following diagram;

---------------CSi-------------------------
|rrooyy----------stock------------yyoorr|
|rrroooyy-----single-plate------yyooorrr|
|rrrrooooyy---twin-plate-----yyoooorrrr|
--------------------------------------------

I'm trying to illustrate by r for red and o for orange and y for yellow is the friction exercised by the clutch and that for each upgrade the friction spectrum is wider and longer; and thus amplification of torque transference during periods of slip occurs.

If anyone proficient in visual diagram creation would like to assist with graphics, you can offer to make me illustrations of a red to yellow to white to yellow to red gradient color spectrum in three rectangular length boxes, varying the gradient according the example above to represent each clutch model's theoretical impact on handling.

Lotus Elise 111R (non-RM) Test Spec
--------------
319HP
759KG
--------------
GT Auto
------
+ Front Aero
+ Extension Aero
+ Rear Aero
* Aero @ 0 F / 20 R
------
Tune Shop
--------------
+ Weight Reduction 3
+ Window Modification
+ Carbon Hood
+ Chassis Reinforcement (!Amplifies erratic handling; Test Spec)
------
+ ECU
+ Engine Tune 3
+ Sport Intake Manifold
+ Race Air Filter
+ Sport Exhaust Manifold
+ Sport Catalytic Converter
+ Titanium Racing Exhaust
+ High-RPM Turbo
------
* Stock Transmission (!All test scenarios)
------
* Stock Clutch
+ Single-Plate Clutch
+ Twin-Plate Clutch
* Stock Flywheel
+ Sports Flywheel (!Coming Soon)
+ Semi-Race Flywheel
+ Limited Slip Differential
@ Initial: 12
@ Acceleration: 30 or 50 (!See test scenarios)
@ Deceleration: 16
------
+ Fully Customized Suspension
@ Ride Height: 0 F / 0 R
@ Spring Rate: 4.9 F / 7.2 R
@ Damper Ext: 7 F / 7 R
@ Damper Cm: 7 F/ 7 R
@ Anti-Roll Bar: 4 F / 4 R
@ Camber: 0.0 F / 0.0 R
@ Toe Angle: 0.00 F / 0.00 R
------
* Brake Controller @ 5 F / 5 R
------
+ Race Softs
--------------

 

[nasanu]

Wow you have put a lot of effort into this. I look forward to testing this out when I get some time off. I didn't think PD went into that kind of detail in their physics model, would be nice if I am proved wrong.

 

[budious]

Wow you have put a lot of effort into this. I look forward to testing this out when I get some time off. I didn't think PD went into that kind of detail in their physics model, would be nice if I am proved wrong.

I think there is a lot hidden below what we see, they spent 6 years on this. They just got hung up on making the buttons so we could access it all... maybe patch v2.9 will bring it up all to speed about 3 months before GT6 comes out.

 

[BlueShift]

(...) So now you're probably thinking, "so why would the best 'not be the best'?" (...)

After reading this, I'm quite speachless.
If you're rigth, you're a genius, because you may have cured the Yellowbird

I'm testing this rigth away.

(another ext damper = comp damper setup damn it ! )

PS - since I'll test what you did, could you describe how you call the effect of what I call "autoturning" which is a LSD/susp/aero effect at braking (while braking, the car turn all alone with only sligthly touching the direction then release it, just by weigth and then she follow the curve nicely).

This is very clear on my Stratos setup (lots of oversteers, beware), I'd like you to tell me how you analyse it because I'm searching this "graal" for every MR i make... (the ultimate graal is suspension autoturning, which I made that on a car but I don't remember which one, it may be the Zonda).

PPS - man, you are mad to put this before a tuning competition, with a 4RW. It's quite a fatal weapon there if you're rigth, like the atom bomb, you should have kept this for yourself at least to have an advantage over others ... I'm planing to put my research / "omg that was that tips" / secrets on the suspension after this one

PPPS - I disagree with 2 things on the test setup : a-roll bar should follow the weigth % of the car, brakes (the same). For those two settings, it should be something like 4/6 and for brakes 4/6 or 2/3 but it'll test in the same condition as you made.

Those two settings alone + lack of camber (camber/toe set at 0/0 for this test is the exact right thing to do) destroys all natural lateral forces movements effects, so... You may have read "something different". Because you front train with "natural settings" (4/6 and 2/3, let's say, if the natural weigth is 40%/60%) should be "weaker" on lateral forces if you see what I mean.

 

[budious]

PS - since I'll test what you did, could you describe how you call the effect of what I call "autoturning" which is a LSD/susp/aero effect at braking (while braking, the car turn all alone with only sligthly touching the direction then release it, just by weigth and then she follow the curve nicely).

PPPPS - you forgot the tranny setting ! (which is capital when you check LSD)

Those two settings alone + lack of camber (camber/toe set at 0/0 for this test is the exact right thing to do) destroys all natural lateral forces movements effects, so... You may have read "something different". Because you front train with "natural settings" (4/6 and 2/3, let's say, if the natural weigth is 40%/60%) should be "weaker" on lateral forces if you see what I mean.

" * Stock Transmission " on the Test Spec

Rolling through the corner is not the same as surging. Try it on the first hairpin after the long straight on Deep Forest, you will brake hard enter the corner, if you can eye the speedometer while you do this, it will go from 150MPH to 60MPH very quickly, let off the brake without giving it throttle, the car surges forward back up to around 80MPH without touching the throttle, this is the residual spin left in the Semi-Race flywheel which has not slowed down yet. Switch the fly to stock or sports and note the difference.

Regarding zero cam and toe, it's just mute on most of my testing. Occasionally I do post a tune with one or the other, but only when it produces constant favorable results under a wide array of track conditions on multiple grades of tires. Since I do my tuning process incrementally and build stock up, I spec lower grade tires which may not grip as well with aggressive camber/toe. If you think you're missing an extra %0.5 of lap time then I won't get offended if you tweak them yourself.

 

[BlueShift]

" * Stock Transmission " on the Test Spec

Yeah I saw that, I just can't read and removed it but you reacted first

Rolling through the corner is not the same as surging. Try it on the first hairpin after the long straight on Deep Forest, you will brake hard enter the corner, if you can eye the speedometer while you do this, it will go from 150MPH to 60MPH very quickly, let off the brake without giving it throttle, the car surges forward back up to around 80MPH without touching the throttle, this is the residual spin left in the Semi-Race flywheel which has not slowed down yet. Switch the fly to stock or sports and note the difference.

There's two problems
- one is using an automatic box. I just can't so I'll roll through the tests without
- the second is the rear train's unnatural reactions to lateral force due to a lack of 40%/60% (say this is it, your balance seem to be 40.4958%/59.5041%) a-roll bars and braking.
So with full lateral forces, you'll need to resist a-roll with a balance set to 40% divided by 60% : 2/3, 3/5 (let's say it's a usefull approximation) or 4/6.
You have the exact same balance on your brakes : you'll have 40% of your weigth in front and 60% in the rear. So, you should brake with the same balance : you should choose 2/3, 3/5, 4/6, 5/8, 6/10.
Now aero. It's difficult for my model because front is 0. You have 20° more than in front and have 40%/60% weigth. But in fact you should "push" 0.66 more in rear.
Usually I take sin(front) / sin (rear-front) = front weigth / rear weigth (=0.6666 in your case).
Here sin 0 = 0 so I'm screwed. I have a second quick formula, which don't diverge at 0° which is front = 1.2*rear - 15. Here it says rear aero = 13°.

Regarding zero cam and toe, it's just mute on most of my testing. Occasionally I do post a tune with one or the other, but only when it produces constant favorable results under a wide array of track conditions on multiple grades of tires. Since I do my tuning process incrementally and build stock up, I spec lower grade tires which may not grip as well with aggressive camber/toe. If you think you're missing an extra %0.5 of lap time then I won't get offended if you tweak them yourself.

My camber formula is screwed again because of front aero set to 0, so i'll neglicted that front part. With 13°, it says -0.9468 rear, so -0.6312 front (-0.9468*0.666), you get -0.6/-0.9. With sin², I get -1.3/-2.0, I have to test that on high speed ring.

If I follow all my theory, damper ext should be tuned too.
You set your flat comp to a "strength" of 7, having flat comp is rigth because your RH is flat and your SR are, say, with a good front/rear balance. But they are weak.
Ext dampers acts with springs. Comp dampers act against springs. Hence, Ext < Comp is logic.
I want to say 5/4 for dampers (so -2/-3 from your 7/7 comp but maybe I should have choosed a 6/6 comp, maybe increasing SR by a 16% front and rear (from 7 to 6) to compensate that so that'll make 4/3 and reflect again perfectly front/rear weigth translation, horizontally and "vertically") , but it need testing on High Speed Ring or the Spiral of cape ring, esp with camber, aero set all by my "to be perfected" math theory.

After that, I'd determined the true RH. (I'm doing it all the opposite it should be ) so... I'll give you if I find it, for sure.

All of that increase a hell lot of your speed in curve, because your car will resist lateral forces "naturally", with no unbalance. You'll get something like +15-20% speed in really speedy curves from your settings I think. Using camber but appriopriate comp/ext will also improve braking. Not to a rally better point, since it's difficult to compete with mute camber/toe settings. Try that on that car, just for the experience of it.

Oh, and I agree on mute toe. Anyway, with my theory I never have to use it : the few times I used, I may have screwed the clutch, so... If you helped me remove the toe, I'm very thanksfull

 

[budious]

Dunno, I do have a system, but then again I also just drive it until it feels right and that can go against the system sometimes. Like on my original Lotus 111R tune I was running the brake balance 4F/6R but for my braking line on this setup, 5F/5R just seemed to flow better. I posted 1:13.018, 1:13.024, 1:13.180 during this testing across three different configurations of drivetrain equipment. If you can find tweaks to suspension, aero, or brake balance but using stock transmission and put my time below 1:12.999... I'd be impressed, that or I just need to practice more.

Spring rates once you're in the right neighborhood are a bit of voodoo anyways, I can give examples of where bumping it up one way gets me +.5sec on the first half of a track's checkpoint then I finish -0.5 sec down at finish line, bump it down one notch and it's -0.5 sec down in the first checkpoint and then +0.5sec at the finishline. Generalizations are close enough, my driving ability is margin of error well beyond the spring rate offset I'm sure. Depends which section of the track you want to be faster on, hence, I place emphasis on consistency over top lap time.

 

[BlueShift]

Hahaha no, I can't, because I can't drive on that track . I sumurize the tune, try it and tell me (hey I'm trying your car, try mine )
Remember, I don't even tried it ! Remember there's (lots of) improvement on SR/RH to be made (high RH is why you don't benefit from your chassis)


Aero 0/13

@ Ride Height: 0 F / 0 R
@ Spring Rate: 5.6 F / 8.3 R
@ Damper Ext: 4 F / 3 R (i'm not sure if it's 4/3 or 3/4, try both, i think 4/3)
@ Damper Cm: 6 F/ 6 R
@ Anti-Roll Bar: 4 F / 6 R (or 3/5, 2/3... please use 2/3 or 4/6 to counter perfectly lateral)
@ Camber: -0.6 F / -0.9 R -> maybe you'll have to tune better your accel esp if you go to -1.3-/2 (edit : front/rear typo sorry)
@ Toe Angle: 0.00 F / 0.00 R
------
* Brake Controller @ 4 F / 6 R (or 2/3, 3/5... etc)

I think we may be a good team

 

[BlueShift]

1'16.924, I' do want to compete but :
a - I'm not a specialist
b - I just can't drive generally speakin.

But I've got an irl friend that is #10 on the drift on that track so maybe if I will give him the two car + the two setup, he would tell

Anyway try it, it is really nice. You'll need 4 less clicks on the accel, I think. Maybe more initial, like 25.

 

[budious]

You gave a few too many variables to try out here all at once but I sat down and raced the first set, all in all, for my driving it was pretty on par. I did successfully adapt your A/R and Toe to my suspension setup and managed, 1:12.924 - a 0.094s improvement.

I tested between the setups on my non-chassis reinforced variant of the car as it would be less sensitive to minor inconsistencies using the single plate clutch, stock flywheel, LSD@12/30/16 that proved consistent through my first batch of drivetrain testing.

About the aero, you claimed @ 13 R and I tried that with your tune and was only doing about 1:14", then I bumped to @ 20 R and managed 1:13.038" but it's practical theory against practical application.

About the brake balance, I found the combination of 4 F / 6 R to spin the rear around approaching the apex of the first hairpin, even using the camber the rear end comes loose. 5 F / 5 R provided a nice linear and straight line deceleration path through the corner for my driving technique on the track.

How are you calculating spring rate? I think you are computing the actual car weight of 759KG, but for real spring tuning, a portion of that would be unsprung weight that makes up the wheels, suspension arms, axles, brakes, rotors, etc., and only the sprung weight that sat upon that portion of the frame would need to be calculated. I don't know the ratio for this car in real life or whether or not GT5 implements that distinction but I assume it may as your settings feel a little too stiff for me. For theoretical example, let's pretend 200KG is unsprung weight, and calculated me spring rates for 569KG.

Anyways, hybrid result standing:
RH: 0 / 0
SR: 4.9 / 7.2
DE 7 / 7
DC 7 / 7
AR 4/ 6
Cam(-) 0.9/0.6
Toe 0/0
BC@5/5

Test scenario 5 was used (SP Clutch, Stock Fly, LSD @ 12/30/16)

 

[BlueShift]

How are you calculating spring rate? I think you are computing the actual car weight of 759KG, but for real spring tuning, a portion of that would be unsprung weight that makes up the wheels, suspension arms, axles, brakes, rotors, etc., and only the sprung weight that sat upon that portion of the frame would need to be calculated. I don't know the ratio for this car in real life or whether or not GT5 implements that distinction but I assume it may as your settings feel a little too stiff for me. For theoretical example, let's pretend 200KG is unsprung weight, and calculated me spring rates for 569KG.

No it's easier than that.

SR: 4.9 / 7.2
DE 7 / 7
DC 7 / 7

I wanted to go to DC 6/6. To keep having your compression "feel", from 7 to 6, since spring plays the same direction than SR, if I go to 6/6, that 83% of 7/7. So to continue to have your "7/7 feeling" with 6/6 DC, I need 116% of your front SR and 116% of your rear SR. Hence the two values I posted. I made the hypothesis that you knew perfectly front/rear distribution (40%/60%).

759kg don't play a role in that, in camber it does.

I did sin(front aero) * 759 * 0.4 / 100 = front camber (but since sin 0 = 0 this irrelevant)
And sin(rear aero) * 759 * 0.6 /100 = rear camber.

Then find back the front camber with : front camber / rear = 0.6666.

It would be easier to know what is the real RH so we knew perfectly how many kg are under each train. I've got a magic thing for that, I search this and edit that here just in a few moment.

(edit : true RH of that car is 115mm/115mm for 0/0 RH, so 4.9 @ 115mm = 563.5kg and 7.2 @ 115 mm = 828kg. If you go to -25/-25, that makes 90mm/90mm which is sufficient even for the Nür (~65mm from the road)

From 4.9/7.2 ... which are 563.5kg / 828kg : 563.5/90 in front (so 6.26) and 828/90 in rear so 9.2).
So RH -25/-25 gives you a SR of 6.3kg per mm/9.2kg per mm, or 567kg/828kg if you prefer, from your spring, you won't tell any difference. It'll be less randomish and chassis stiffening should benefit greatly from that (it's why it's made for).

True RH is my best kept secret, I won't talk about that before the end of the first tuning application in two weeks or so. You can make balanced unflat RH setup with that, with all things about lateral force I told you and DE playing with the springs/DC playing against, my setups wouldn't be special anymore
No it don't involve cheating at all (really), and no not everybody will be able to find that data after I gave the solution. I'm just a lucky witty boy that... ah no I won't tell. just wait.

I'm off to bed now, I'll test each scenario and post my times, but I can't drive on that track, my best time is 1'16.9xx
That can't be soon. Tuesday I'm off GT5...

 

[budious]

I did successfully adapt your A/R and Toe to my suspension setup and managed, 1:12.924 - a 0.094s improvement.

I tested between the setups on my non-chassis reinforced variant of the car...

Anyways, hybrid result standing:
RH: 0 / 0
SR: 4.9 / 7.2
DE 7 / 7
DC 7 / 7
AR 4/ 6
Cam(-) 0.9/0.6
Toe 0/0
BC@5/5

Test scenario 5 was used (SP Clutch, Stock Fly, LSD @ 12/30/16)

This is also a good textbook case of how chassis reinforcement handles differently.

Tried the same numbers for almost 10 laps running times between 1:13.6" to 1:14.3" with above settings. Then I zeroed out the camber, second lap on no camber I run 1:12.798" ...

Test Spec (no chassis reinforcement) w/ camber = 1:12.924"
Test Spec (chassis reinforcement) w/ no camber = 1:12.798"

...