Crazy BanZai Tuning Attack!

  • Thread starter Thread starter KaiZen
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What is the best track for your Crazy BanZai Tuning Attack?


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HAHAHA.. I got the title from a drift comp downunder in melbourne! :crazy:

So, this is one for all you Tech Guru's out there. I know we have our beloved M-Spec Tuning guide but I'd like to know how you pro's do it.. :bowdown:


How do you go about setting up your cars? What is you Crazy BanZai Tuning Plan of Attack? :drool:


In some sort of detail, please.. It doesn't have to be an essay, but at least show your own process of setting up your cars, eliminating problems and ultimately tuning the car to achieve the right amount of balance for your own driving style :D


Allow me to help you start it off.. 💡

If it's an FF, FR, 4WD or MR I would start by.. <insert tech guru info here> :sly:

I look at the cars natural balance.. or tune according to it's great ability to.. or start by countering it's understeer/oversteer tendancies.. etc..

Please consider the track or tracks you are setting it up for. The power and weight, weight distribution of the vehicle and anything else you think about whilst tuning your cars for overall balance..


Come on Tech Guru's.. Don't be shy!! show me your...

Crazy BanZai Tuning Attack!!! :bowdown: :eek: :drool:




This, I hope, is going to be interesting.. :nervous: :scared:

Cheers! :cheers:

KZ
 
When it comes to test tracks, I use Midfield to set up the maximum gearbox length, Grand Valley to sort out the high speed handling and Trial Mountain Reverse to iron out the low speed handling.

I wrote a "How I go about setting a car up" article a couple of years ago - no doubt some of my opinions will have changed since then but I'll dig it up and post it here for everyones amusement ...
 
I’ve been wracking what passes for my brains trying to come up with something to add to this thread which hasn’t already been covered previously. The ‘core’ subjects of gearboxes, differentials and handling have all been broached with considerable success (primarily by NumbOne), so, rather than attempt to rehash something that has already been done here, I thought I’d take a leaf out of Gasman’s book and detail a general description of how I go about setting a car up for GT3. However, I haven’t laid out the process all the way through to tweaking differentials, anti-roll bars, camber and toe. This is about getting the basic balance of the car worked out in a rational way.

There are a few rough principles that I employ and hopefully some of the following might be new ground. At the least, hearing my take on a given facet of tuning may inspire someone else to thinking “That’s not right!” and posting a response as to where I goofed. So please feel free to spindle, fold and mutilate what I’ve written and don’t be shy about sticking the knife in. This is only my opinion and, in the words of the song, “It ain’t necessarily so!”.

First things first. All of the following is coloured by my driving style, so it’s best to make that clear from the outset. I’m a fully paid up member of both the ‘Slow In, Fast Out’ and FR/MR clubs. How I take corners, in the main, is to slow down to the ball-park entry speed and position (determined by experience) with steadily increasing brake pressure; pulsing the brakes if I require a more rapid deceleration. Relaxing on the brakes, I then start to make the necessary steering input but enhance the turn-in by a further quick dab on the brakes. Depending on the corner and the general characteristics of the car I’m in, I then either accelerate through the apex and exit or coast into the first half of the apex before throttling on. I avoid ‘drift’ if at all possible and in powerful rear wheel drive cars I’m usually counter steering as I exit to keep the tail in line. The latter is largely due to a flaw in my driving that I can’t seem to cure, this being that I keep steering inputs ‘on’ a fraction too long as I accelerate. Controller wise, I use analogue steering but digital accelerator and brakes with gear changes on Auto (I know, I know … what a wimp!). {No longer an AutoBoxer these days ... huzzar!}.

STAGE 1
When I’m beginning to set a car up, my first port of call, after fitting all the required engine, transmission and suspension modifications, is to take it out at ‘stock’ values on T2 (Super Hard) or Simulation tyres.

The point of this ‘pre-tuning’ run is to show you where the problems are in the cars handling, so I would recommend turning ASM and TCS off. The tracks I use for this are Grand Valley and Trial Mountain Reverse as I find they give me all the ‘environmental’ factors I need (smooth, fast sweeping corners; smooth, tight and/or blind corners; uneven surface/variable camber corners; downhill and uphill braking; long and short straights etc).

There are two reasons I like to use T2’s or Simulation tyres for this. Firstly, I nearly always race on T2’s (most pit stops take too long for you to be able to complete a 15 lap race quicker on soft compound tyres as the time lost in pitting is greater than that gained by the faster lap times). Secondly, the low grip coefficient exposes any weaknesses in the cars handling much better than if you run softer tyres.

STAGE 2

To facilitate testing, I now set the gear box up for the circuit. The parameters I use for this are fairly common to all of us i.e. decent acceleration coupled with attaining a pre-determined top speed, at the red-band, in top gear, at the end of the longest straight.

Because I use the buttons on the D-Pad for accelerating and braking, I will also try and use the gear settings to diminish power-on oversteer (I don’t have the delicacy of touch required to apply less than about half throttle, so some big horse-power, no aerodynamics, cars tend to squirm the back end out on me during corner exit). This can mean I’m getting less than optimal acceleration in low gears out of corners but it’s a trade off I’m willing to make for the sheer ‘manliness’ of low TCS values!

How to set the ‘box up has been excellently explained before by NumbOne so all I have to add is that the magnitude of the Final Gear value seems to have a definite impact on the way the car handles.

A low Final combined with a narrow Autoset gives an agile, responsive car and works very well with NA engines and their, generally, wide torque range. A large Final with a broad Autoset appears to reduce, to some extent, the power-on oversteer I mentioned above, especially with enormously powerful turbo engined cars. This may well be because such a set-up tends to allow you to ‘hold’ a higher gear in a corner whilst the relatively low road speed as you start to apex means that you begin accelerating from lower revs (i.e. away from the power band) and thus are putting less torque through the drive wheels. The fact that the drive gear has to rotate more times for each axle rotation may also smooth out power delivery.


STAGE 3

Now that the gearbox is matched to the track, you can now start to tune the suspension. For me, the single most important element to get right, at the initial point, is the weight loading of the springs. In both absolute terms and in relation to each other, the front and rear spring rates are the foundation upon which everything else stands. Get this right and all the other adjustments are much easier to apply as you can concentrate on modifying the handling rather than ‘masking’ a bad choice of spring rates.

I work from the (possibly erroneous!) assumption that, when you fit Fully Customised Suspension, the ratio of Front to Rear spring rates it has at default is one which neutrally balances the car when it is at rest. In other words it is showing you where the longitudinal Centre of Gravity lies by having stiffer spring rates at one end, thus indicating where the largest proportion of the weight is. Sadly we don’t have the data to calculate the true C of G but it is still useful to know where along the vehicles length is its point of rotation. For most of the race modified FR and MR cars it seems that the front springs are supporting from 52.5 to 53.5% of the weight whereas for 4WD’s it’s nearer 54% (the extra coming from the front differential I would guess). There are a few exceptions to this (for example the Raybrig NSX has 54% of it’s weight towards the rear) but it seems generally true.

To work this out for the specific car you’re working on, simply divide the Front Spring Rate by the total of the Front and Rear Spring Rates.
It is also useful to note what fraction the Rear Spring Rate is compared to the Front e.g. if the Front Rate is 7.6 and the Rear Rate is 6.5 then the Rear is 0.8553 of the Front. You can use this value to maintain the relationship between the Front and Rear Springs by calculating what the Rear Rate should be after you’ve adjusted the Front. For example, if the ratio is 0.8553 and you set the Front Spring Rate to 12.7 then the Rear should be 10.8 or 10.9 (12.7 x 0.8553 = 10.86).

As the game does not take into account weight reductions when assigning the default spring rates it is important to note what the cars weight is both before and after weight reductions are applied. Using this as a percentage you can then reduce the spring rates accordingly. For example, a TVR Tuscan weighs 1100kg stock and 979kg with a Stage 3 Weight Reduction. This 11% drop in weight can then be applied to the spring rates. Default springs on the Tuscan are 7.6/6.5 so, with less weight being carried, these can be softened to 6.7/5.7 (or 6.8/5.8 if you want to round up rather than down!).

A better way of doing this is to reduce the Front Spring Rate by the noted percentage drop in weight and then calculate the Rear Spring Rate from this by using the ratio of Rear to Front rates worked out earlier.

Having re-rated the springs for the reduced weight, you can now alter the ride height. If it is lowered (and it usually is!) then the Spring Rates need to be stiffened. As a ‘quick fix, for each millimetre you reduce the ride height, you should increase the springs by 0.1kg to compensate for the shortened stroke. In rounder numbers, if the ride height is reduced by 1cm then increase spring rates by 1kg.

A more accurate approach is to use a simple equation to calculate how much stiffer the Springs need to be to give the same resistance to ‘bottoming out’. You can do this as follows:

For a given end of the car, multiply together the Cars Weight (W1), Spring Rate (S1) and Ride Height (R1). This will give you a constant. I’ll term this number “Loading” (L) for want of a better name!

When the Ride Height is changed (call the new height R2), you can work out the new required Spring Rate (S2) by:

S2 = L / (R2 x W1)

For example, the Spoon S2000 Race Car has a weight (W1) of 1050, a ride height (R1) of 90 and Spring Rates of Front 14.5, Rear 12.1.

W1 x S1 x R1 for the Front = 1050 x 14.5 x 90 = 1370250
W1 x S1 x R1 for the Rear = 1050 x 12.1 x 90 = 1143450

If the ride height is changed to 80 (R2) then for the Front

S2 = L / (R2 x W1) = 1370250 / (80 x 1050) = 1370250 / 84000 = 16.3

And the Rear

S2 = L / (R2 x W1) = 1143450 / (80 x 1050) = 1143450 / 84000 = 13.6

A thing to note here is that although ‘bottoming out’ has not been properly implemented in GT3 (a serious flaw in my opinion), slamming the ride height to the bump stops can have an impact on tyre wear. This is because although lateral thrust forces are reduced by a lower ride height, vertical pressure forces between the sprung and unsprung masses are sharpened by shorter, stiffer suspension. The tyre is having to absorb more of the shock imposed by the road surface because the springs don’t ‘give’ as much i.e. they resist the road rather than comply with it. This can be moderated by careful setting of the damper Bound and Rebound but it’s a compromise between wear and handling (which handling will usually win!).

[As an aside, it is possible to find published real world figures for a cars weight, spring rates and ride height. Certain factors aside, the physics engine for GT3 is quite accurate and using these ‘actual’ (as opposed to ‘virtual’) settings is perfectly plausible].

In a race-bodied car, there is one final thing the springs may need to be adjusted to compensate for, changes in Downforce. If we assume that the Downforce figures in the tuning interface represent a percentage increase in the effective weight and that the stock Spring Rates reflect this, then if the Downforce is changed we have a different weight value to deal with when the car is moving at speed.

In the real world, Downforce obeys the Inverse Square Law i.e. if you double the speed then you get four times the Downforce. Because speed is one thing that is never constant (for long anyhow) in GT3, it would require averaging a large summation equation to arrive at an entirely accurate answer – and you’d have to recalculate it for every track! However, luckily it is a valid approximation that, over the entirety of a course, a car will produce an average speed that will generate half the maximum Downforce.

To calculate the new Spring Rate (S2) at each end of the car for a given change in Downforce is relatively straightforward. We know the weight (W1) of the car, the change in Downforce (New Value – Old Value or (D2 – D1)) and the current Spring Rate (S1). The equation to work out S2 is:

(( W1 + ((( D2 – D1 ) x W1 ) /2 )) x S1 ) / W1

It might look a bit complicated with so many brackets but basically all it’s really doing is giving us:

(Downforce Modified Car Weight x Original Spring Rate) / Car Weight

Using the Spoon S2000 Race Car as an example again and assuming we maximise the Front Downforce, the values we have are:

Car Weight (W1) = 1050
Original Downforce (D1) = 0.45
New Downforce (D2) = 0.74
Front Spring Rate (S1) = 16.3

So, S2 is determined as:

((1050 + (((0.74 – 0.45) x 1050) /2)) x 16.3) / 1050
= ((1050 + ((0.29 x 1050) /2)) x 16.3) / 1050
= ((1050 + 152.25) x 16.3) / 1050
= (1202.25 x 16.3) / 1050
= 18.66

To work out the Rear Spring Rate if the Rear Downforce is changed, then simply plug in the appropriate values.

With ride height and springs adjusted, it’s time to take her out for a test run. It might be worthwhile to set Bound and Rebound to 1 for some of this testing as practically zero damping can highlight whether the basic front/rear balance is askew. Analyse how she handles and do quite a few laps until you’ve got the car, the track and your driving matched – the ideal is that you can turn in consistent laps (within a tenth of a second or so) as this allows you to more easily assess the effects of changes you subsequently make. If you can’t get that level of consistency out of her (and if you can she probably doesn’t need any more setting up!) record your average time and move on to the next stage.


STAGE 4

You’ve now got baseline figures to work with and can start adjusting the magnitude of the spring rates. Unless something is very obviously wrong (or works against your driving style) don’t adjust the relative front/rear ratio yet. There are two approaches you can take here. You can either incrementally increase the spring rates (for instance by half a kilogram a time) or you can do it by high/low searching i.e. initially large changes gradually getting smaller as you home in on the most comfortable value. It’s solely a matter of personal preference and the amount of time you want to spend.

Getting this vital stage right can take a fair amount of time as it can be difficult to decide between the conflicting outcomes desired. Speed (not to be confused with lap times) and handling are not entirely mutually exclusive but enhancing one generally impacts negatively on the other.

It is sadly true that whilst harder springs improve responsiveness to steering, braking and acceleration inputs (all Good Things) they actually reduce grip (not at all a Good Thing!). The trick is to find the compromise value that works for you and gives you the fastest consistent lap time. A spring rate is no good if you’re not comfortable with it as it’ll take too much concentration for you to be consistently quick in longer races – a blisteringly fast time one lap, followed by an ‘off’ on the next, is not as fast as two slightly slower laps run clean.

When you’ve found a rate that seems to work for you (you’re cleanly turning in faster average lap times), it is tempting to try and alter the balance of the car during cornering with the ratio of front to rear springs. It can be done, no question about that, but cornering balance is more properly the job of other suspension components.

Setting the springs to balance a car during cornering will have an effect(and more than likely not a good one!) on all other aspects of the cars character, such as acceleration and braking. The problem is that spring rate is an ‘always on’ type of setting (has an effect all the time) whereas such components as dampers and anti-roll bars have transitional settings (only come into play during the state changes they’re designed for).

So unless you have a real problem with something like uncontrollable power-on oversteer, I’d suggest leaving the relative spring weights more or less alone. Experimenting with small variations will probably do no harm but radical shifts in the relationship between front and rear (such as making the rear rate higher than the front in an FR car) may well mean that you’re fighting against the basic chassis geometry the car was designed with. I’m not saying that such variations wont work but that you should be cautious with them.


STAGE 5

With the spring rates pegged, you now have a platform upon which you can perform changes to another candidate for the ‘Most Important Component Setting’ award – the Dampers!

Getting the damper values dialled in to match the spring rates can do wonders for the handling of a given car. As with so much of tuning within GT3, it can be something of a ‘Black Art’ and is heavily dependant on driving style but, over time (and excessive reading on the subject of damped spring systems!), I’ve come to the discovery that it’s actually quite simple to determine what the damper values should be initially set to.

I have to admit that this conclusion is based on the assumption that, within the game, the springs and the dampers are rated to match each other at maximum values. As GT3 doesn’t give dampers any units of measurement, I had to take a fixed point of reference and that seemed a logical one. I added what I’d researched about such things in the real world to that assumption, did a little maths, a graph or two and, voila:

The Rebound value is equal to half the spring rate for the end of the car the damper is at and the Bound between a quarter and a half of the Rebound.

However, it’s by no means assured that the outcome of my assumption is correct, all I can say is it seems to work (at least for the highly tuned cars most of us like to put together!).

Now this isn’t set in stone, it’s just your starting point. From these first settings you can then begin to fine tune the dampers for your driving style, desired handling characteristics and specific courses.

As has been linked elsewhere in the Numbers, a good source of advice on this is “Neil Roberts Article on Shock Tuning at http://www.smithees-racetech.com.au/theory/shocktune1.html". It’s straightforward reading and he breaks a cornering manoeuvre down into five phases rather than the more usual three (which can help in diagnosing where a particular problem lies).

STAGE 4 and STAGE 5 are actually somewhat of a combined process. Because the spring rate chosen was arrived at with a given bound/rebound setting (albeit the stock value for a fully custom suspension), you may find that, once you start to dial the dampers in, the springs appear to be too hard or too soft. In this case, you might have to begin altering the springs and the dampers together i.e. select a new spring rate, adjust the dampers to it as noted above and re-test. This violates the tuning maxim of “Only change one thing at a time” but springs and dampers are so closely integrated that sometimes you have no choice.

Once all this is done, you can move on to adjusting the LSD and the camber/toe/anti-roll bar equation. But that’s a story for another day (is that a sigh of relief I hear!).
 
Here's a clarification/restating of some of the above that I wrote a little later when discussing the original text with some of the luminaries here at the Planet:


There are two ways in which you can approach working through the equations to get a final result. The first is to do each stage seperately and is the easiest to understand (which is why it's the one I posted).

The other way is to do it all in one calculation. This appears on the surface to be much more complicated but once you realise that if something doesn't apply (like no downforce adjustement for example) the value of that term is 0 then it becomes clearer (and it's much quicker to do as well).

For clarity, however, it's probably best to stick with the 'staged' application.

To start with, you need to note down the vehicles 'stock' values for:

Weight
Spring Rates
Ride Height
Downforce

It's therefore important to get the cars stock weight before applying any weight reductions.

It's also very useful at this point to work out the ratio between the Front and Rear Springs - this is simply the Front Rate divided by the Rear Rate and vice versa e.g. if the Front Rate is 7.6 and the Rear Rate is 6.5 then the Rear is 6.5/7.6 = 0.8553 of the Front

Calculating what percentage of the total weight of the car is at each end is generally helpful too in terms of getting a mental picture of where the 'heavy' end is. You can work this out easily for any car by summing the Front and Rear Spring Rates and using that number as a divisor for each Spring Rate individually. e.g. if a car has springs rated at 14.5 & 12.1 then the Front is bearing 14.5/(14.5 + 12.1) = 54.5% of the total weight and the Rear 12.1/(14.5 + 12.1) = 45.5%.

To compensate for a lighter vehicle after Weight Reductions have been made, it is possible to work out how much to soften the Springs by quite easily.

You know the original weight and the weight after reductions so the percentage reduction in mass is given by:

1 - (new weight / original weight)

For example, a Tuscan weighs 1100kg stock and 979kg with a Stage 3 Weight Reduction so 1 - (979/1100) = 0.11 or 11%.

It's probably more useful (and involves less number crunching) just to obtain the ratio between the weights i.e. 979/1100 = 0.89.

Apply this reduction to the Front Spring Rate (e.g. a 7.6 kg/mm spring becomes 7.6 x 0.89 = 6.764 (6.7 or 6.8 whatever you prefer).

We worked out the ratio between Front and Rear Spring Rates earlier so we can work out the Rear from the Front by multiplying the Front rate by that ratio:

6.7 x 0.8553 = 5.7

So now we know that a fully weight reduced Tuscan's spring rates should be:

Front = 6.7
Rear = 5.7

Next, we'll want to change the Ride Height. If we do this then the Spring Rates need to change again to compensate.

The process is to multiply the current Spring Rate by the current Ride Height. This gives us a number we can use as a constant in a simple equation. Call it C.

C (the constant) = S (Spring Rate) x H (Ride Height)

Simple re-arrangement gives:

S = C / H

By itself this means nothing but if you want to alter the Ride Height (H) then it can allow you to calculate what S should be to match.

For example, if the Spring Rates are 6.7 and 5.7 on our theoretical Tuscan and the original Ride Height is 79 then, for the Front:

C = 6.7 x 79 = 529.3

And for the Rear:

C = 5.7 x 79 = 450.3

Say we lower the Front Ride Height to 70 and the Rear to 75. We just plug the numbers into the S = C / H equation:

S = 529.3 / 70 = 7.6 for the Front

and

S = 450.3 / 75 = 6.0 for the Rear


A more complicated thing to work out (but still not that hard once you work out the method) is any changes altering Dowforce will require in the Springs. (I'll just copy in what I posted in the Numbers for this).

In the real world, Downforce obeys the Inverse Square Law i.e. if you double the speed then you get four times the Downforce. Because speed is one thing that is never constant (for long anyhow) in GT3, it would require averaging a large summation equation to arrive at an entirely accurate answer – and you’d have to recalculate it for every track! However, luckily it is a valid approximation that, over the entirety of a course, a car will produce an average speed that will generate half the maximum Downforce.

To calculate the new Spring Rate (S2) at each end of the car for a given change in Downforce is relatively straightforward. We know the weight (W1) of the car, the change in Downforce (New Value – Old Value or (D2 – D1)) and the current Spring Rate (S1). The equation to work out S2 is:

(( W1 + ((( D2 – D1 ) x W1 ) /2 )) x S1 ) / W1

It might look a bit complicated with so many brackets but basically all it’s really doing is giving us:

(Downforce Modified Car Weight x Original Spring Rate) / Car Weight

Using the Spoon S2000 Race Car as an example and assuming we maximise the Front Downforce, the values we have are:

Car Weight (W1) = 1050
Original Downforce (D1) = 0.45
New Downforce (D2) = 0.74
Front Spring Rate (S1) = 16.3

So, S2 is determined as:

((1050 + (((0.74 – 0.45) x 1050) /2)) x 16.3) / 1050

= ((1050 + ((0.29 x 1050) /2)) x 16.3) / 1050

= ((1050 + 152.25) x 16.3) / 1050

= (1202.25 x 16.3) / 1050

= 18.66

To work out the Rear Spring Rate if the Rear Downforce is changed, then simply plug in the appropriate values.

I hope all that clarifies my progress to date on this Duke.

As has been discussed in the Numbers, there are some problems with this method because I've simplified a great deal to make it easy to work out. For example, the assumption that the original spring rates of a car give us a static snapshot of the weight distibution is fundamental to all of the above. It's not an unreasonable assumption I feel and there is no other way (yet) that I've come up with to get at that information. I've also assumed Constant Rate rather than Progressive Rate Springs (it gets massively more complex if you don't!). Anyway, I wont go into the shortcomings of my work here; I've covered that enough in the Numbers I think.

All I can say is it seems to work (for me anyhow). I get a basic equilibrium matching of Spring Rates from it that are compensated for all the hardware and settings changes that took place.

It's not perfect because it intrinsically retains the inherent understeer set into the rates at the start when you fit the suspension. However, you can cover that with Damper changes or even gradually shading up the Rear Springs until you get the balance you want.

I've got a method worked out for calculating what the Damper rates should be to go with the spring rates that come from these calculations ... but I'll go into that another time!
 
NOW THAT'S A REPLY... just the kind of stuff I was looking for. Very in-depth Sukerkin, can't wait for more!!

It's going to take me a while to digest all this highly useful information, so I'll have to get back to you and relay my thoughts on your technique.

Through what I've seen on some Japanese DVD's, alot of Japanese tuners use between 10 and about 14kg spring rates on just about all types of imports from Preludes, to Accord's and to S2000 (Just watched VTEC Club. It don't mean I'm a huge Honda fan. I've seen similar rates on heavier cars like GT-R's and Supra's). Do your spring rates get that high? If you base your spring rates on how low you set the car it doesn't look like you will have the springs so stiff on most cars.

Do you lower your cars to as low as possible and test them on a certain track? How can you tell a car is bottoming out and hitting the undercarriage or bump stops?

I'll have more questions after I've thoroughly gone through this data..


Can't wait for the next chapter.. feel free to copy and paste replies you've made on other threads.. 💡


Now, where are the rest of you Tech Guru's? Sukerkin can't be the only one!
Don't be shy.. Your audience awaits you! :eek: :drool: :bowdown:
 
Sukerkin,

Just a few quick questions..

Do you lower the cars to their minimum height?.. Do you only increase the Spring Rate according to the amount you've lowered the car? That means that the most you would increase a cars spring rates would only be about 1-2kg, wouldn't that be too soft in the real world? When considering the strength of the spring rate according to the height you are lowering the car, do you also factor in the cars initial ride hide, on stock suspension?


Cheers Mate! Keep up the good work!!
 
Hi Kai

In answer to your questions:

- I very seldom slam cars to the deck. I usually find that to be very detrimental to the handling due to "bottoming out" and weight transfer inhibition issues.

- What I do with the equations and method I've posted above is to preserve the balance of the suspension to compensate for dropping ride height, reducing weight or altering downforce. As the spring rates are generally very soft for road cars in the game, it is perfectly fine to increase the spring rates quite radically as long as you maintain the relationship between front and rear (unless you find after a bit of tuning that in order to get the response you want you need to alter that balance).

- I don't think that I ever considered factoring in the ride height with a stock suspension as all my tuning is done on Fully Custom (do we actually know what the ride height is with a stock suspension?).
 
For a fairly detailed mathematical look at what makes a car "go" take a gander at these articles:

http://phors.locost7.info/contents.htm

In some cases it's not directly applicable to GT3 because of the infamous TWiDuK factor (Things We Don't Know) but regardless they form a splendid introduction to the engineering of suspensions etc.
 
Sukerkin, great info, but the point about the default settings on the race suspension being pre set to suit the cars centre of balance might not be correct for all cars.
I can think of two examples of the top of my head which in my opinion dont comply with this rule.
1. Zonda C12S. Default settings front springs are around 16 and rear are around 10 or 11. I would have to check to get accurate values. This is more a front engine RWD setup than the MR set up this car has. Drop the front spring down to about 10 and the car handles O.K.
2. The NA version of the Supra has the reverse to above. Rear springs are way higher than the fronts which is wrong for this driveline. Change the spring rates down both ends (I cannot remember values I had used) but the car becomes very nice to drive).
There may be more out there as well.

I generally lower the hieght by about 10 mm, add about 2 clicks to the right (harder springs) and set front camber to 4 and rear to 2 and then test. Usually a small change to front or rear sway bar is enough to dial out any understeer or oversteer.
I agree that testing on T2 tires is best as softer tires can mask handling problems.
A car that is set up for high speed corners will be a pig on low speed corners and also the other way around. I usually find a comprimise and do not change from track to track.
Also some tracks can cause problems , SS R11 reverse jumps to mind in that they give very little grip when using T2 tires. Instead of trying to make a proven suspension set up work here I suggest using a T3 or T4 tire to help with grip. A T3 tire will last 10 laps at SS R 11 reverse for 10 laps in the Yarris race and makes a big difference to the car feel without changing any settings. I reckon the grip is so low on this track that it was going to be a wet endurance race track and PD forgot to change the grip level program!
I also drive slow in fast out, but power sliding (drift) out of slow corners is fun.
 
sukerkin
...all that stuff...

wow, even as a fellow engineer (or rather, soon to be engineer), I'm a bit flabberghasted by that
excellent job though, cant see a single point out of place

I had looked at this very aspect of the game on my own some time back, in particular the vehicular load distribution and the effect suspension and damper adjustments have on the COG and weight transfer rates. But I had never taken the vehicle downforce into consideration. Partly due to an oversight on my part, and partly due to the fact that i didnt know if the game modelled it accurately.
I thought it was highly probable (for sake of simplicity) that it was modelled as having a linear relationship with velocity, and not modelled from the equation

CL ~ 2 FL / (p(V^2)Ap
where CL is the coefficient of lift, FL is lift force (or downforce as the case may be), p is fluid density, and Ap is planform area.

Afterall, I dont imagine a game designer thinks his product is ever going to be subject to engineering scrutiny.

some insight on this query would be appreciated, if anyone has something to offer. Also, in regards to the planform area of the spoilers, does anyone know if this is just an average value applied to all vehicles, or if it does indeed vary from vehicle to vehicle as would be appropriate. Sukerkin, I'm looking your way.
My suspicion is that it may share a 1:1 ratio with the vehicles track width, but this is just a suspicion at best. Then again, for shear simplicity, it may have been given a constant value applied to all cars. I have been able to find nothing to either prove or disprove either of these theories.

👍
 
@Uncle Harry - thanks for your kind words (and very interesting thoughts on SSR11).

It's been a few years since I wrote the above and, as I hinted at in my intro, my opinions on some aspects of tuning have altered over time.

I agree with you that the 'static weight distribution snapshot' concept is not going to apply in every case but, other than Real World figures, we really don't have enough information to make any progress unless we make some assumptions along the way.

I have found that if you can find the 'true' weight distribution of a car in RL, then you can use the equations of Simple Harmonic Motion to great effect in determining initial spring rates. This is not a fully fledged idea yet, as I'm still trying to figure out if I can calculate the damping coefficient and the influence of the stiffness of the stabalisers but, if you solve for 'k' (Spring Rate), with an aim of a 1Hz suspension frequency, then you seem (I emphasise seem :D) to end up with a reasonable balance in the handling of the car.

For Ride Height, the rule of thumb I'm applying at the moment (with the above spring rate 'method') is that I adjust up from the bottom bump stop by 1mm for each kg of spring rate below 20 (e.g. a spring rate of 15 translates as a ride height of 5mm). I really don't like using asymetric ride heights, so I do this from the 'softest' end of the car.
 
@Tankspanker - likewise, your good reaction to my old scribblings is much appreciated (especially when it comes from an 'informed' source 👍 ).

With regard to the Downforce question, I'm not sure that it is significant that we don't know the area of the 'wing'. I believe that the force is measured as a fraction of the cars weight in the game so many of the 'normal' parameters simply are put to one side. This, again :o, is an assumption tho' and I don't have any proof to back that up {it could just as easily be a multiplier for 'grip' ... mmm ... ponders ... reaches for calculator :lol:}
 
sukerkin
@Tankspanker - likewise, your good reaction to my old scribblings is much appreciated (especially when it comes from an 'informed' source 👍 ).

With regard to the Downforce question, I'm not sure that it is significant that we don't know the area of the 'wing'. I believe that the force is measured as a fraction of the cars weight in the game so many of the 'normal' parameters simply are put to one side. This, again :o, is an assumption tho' and I don't have any proof to back that up {it could just as easily be a multiplier for 'grip' ... mmm ... ponders ... reaches for calculator :lol:}

Certainly it is not significant
The typical gamer will expect grip to be improved by increasing the spoiler's angle of attack (rotating leading edge downwards, in this case). So in this regard the wing settings perform as expected, and being conscious of any specific surface dimensions is not necessary. Surely they do not perform in a manner that accurately models real-life occurences, but afterall this is a video game and such things should sometimes be excused.

It may very well be true that the wing setting is just used only as a constant multiplier acting on the vehicles mechanical grip. This is a possibility I had not considered. However it does also seem to have some significant effect on the drag force acting on the vehicle, as can be witnessed by altering the angle and doing runs on any track with sufficiently long straights - Test Course being the perfect venue to demonstrate this. Now whether or not drag is modelled correctly is just as precarious a problem as the question of downforce, since they obey the same basic governing equations. So if I may add to your assumption, the wing settings may act as a constant multiplier on both the vehicles grip and drag parameters.
'I dont know', is what it all comes down to, I guess. It just might be another one of the unknowns of the game physics, not dissimilar from the effects of tire width and sidewall ratio on suspension.

Anyways, a definitive answer is not required, this is no more than a curiousity that has lingered with me for some time.
thanks for the feedback and quick reply
👍
 

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