Spring rate confusion

  • Thread starter SilverGC
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SilverGC

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When reading through the tuning guides, I assume that stiffer spring rates mean lower kgt/mm values? Because when I set the value to the highest, I get the opposite effect (e.g. for rear springs, setting it all the way low makes my car oversteer like crazy, and all the way high makes it tight to turn.

But then the suspension guide states this:
Rear Spring Settings
Setting Effect
Rear Stiffer (higher value)Increases oversteer
Rear Softer (lower value)Decreases oversteer

Also, do the same apply for sway bars (lower sway = lower spring rate setting)?
 
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Stiffer spring rates mean a higher value. Softer springs mean a lower value. Same goes with stabilizers and dampers.

Which car are you tuning by the way? Just curious. What kind of oversteer are you experiencing? Is it all the time, out of control? Or is it just under power? Or only when you release the throttle and/or brakes? Is it oversteer on corner-entry? Or mid-corner? Or as you're trying to leave turns?

How about you tell us what car you're tuning, and give us what values you're using.

Making rear springs super-soft certainly can create oversteer in some cases, but it depends on the car. It sometimes depends on what other settings are being used. It also depends (as mentioned) what sort of oversteer is showing up; there are different kinds.
 
Right now I'm working on a R34 GT-R M-Spec Nur.

Ok the set up is this:

Tires:
Racing Super-Soft F/R

Permanent:
Stage 3 Lightening
Port Polish
Engine Balance
Displacement
Stiffness (Roll Cage)

Racing Chip
Sports Chip
Stage 1 Turbo
Racing IC
Racing Brakes
Triple-Plate Clutch
Racing Flywheel
Carbon Shaft

Transmission:
Full Customize, set to general level 7

Suspension:
Racing
Spring Rate Front: 14.2
Spring Rate Rear: 8.0*
Height: 80mm F/R
Bound: 5 F/R
Rebound: 7 F/R
Camber: 2.0/1.0
Toe: 0/0
Stabilizers: 7/1

*I will just change the rear spring rate in order to control the experiment

I am doing practice runs on Tsukuba. We'll take the final large curve before the finish line for example.

Rear spring rate set to lowest (5.0). Build up speed to 6th gear/120mph right before the turn. Let go of gas and turn into right, my car's simply sliding into the turn. Add gas, the car spins even more.

Rear spring rate set to highest (14.2). Build up speed to 6th gear/120mph. Let go of gas, turn into right, I slide off the track and into the wall.

So from my experience, setting rear spring rate to lowest causes huge amounts of sliding, and to the highest keeps it extremely stiff. So if I were to just go about saying this, I'd say stiffer rear increases understeer (since I'm crashing into a wall).

In any case, I'm sure there are plenty of tuned R34s out there. I just want to make the perfect line car; no understeer, no oversteer, just good for turning into lines.

Also, why is everything moderated (even quick replies)... first forum I've seen doing that.
 
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It's pretty well documented that the effects of changing spring rates in GT4 are opposite what you would get in real life. People have come up with explanations, but they aren't really satisfactory for such a blatantly wrong aspect of tuning in the game.
 
Austin343
It's pretty well documented that the effects of changing spring rates in GT4 are opposite what you would get in real life. People have come up with explanations, but they aren't really satisfactory for such a blatantly wrong aspect of tuning in the game.
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Perhaps, but on gamefaqs and the GT4 tuning guide in the sticky also say that higher rear spring rate = more oversteer. But when I turn it up, I understeer into the wall.
 
Hmm. The now-inactive Game Guides at the top of the page acknowledge that there is controversy about what spring rate adjustments do to the car's behavior, but seem to favor your findings. Never having tuned much in the game myself, I took that as truth without reading opinions in other threads. I'll leave it to someone with more knowledge to describe in detail what effects spring rate adjustments have.
 
The problem with the effects of spring rates lies in how all 4 tires are stuck to the ground at all times unless forced off the ground by extreme downforce on the opposite end or bumps in the surface.

A stiffly sprung rear end would normally try to lift the inside rear under properly hard cornering (if the front is softer), but because the game holds the tires onto the ground in effect, it instead pulls on that corner, reducing the force on the outside front.

Soft rear springs do the opposite, trying to lift the inside front but instead reducing pressure on the outside rear.
 
SilverGC
Right now I'm working on a R34 GT-R M-Spec Nur.

Ok the set up is this:

Tires:
Racing Super-Soft F/R

Permanent:
Stage 3 Lightening
Port Polish
Engine Balance
Displacement
Stiffness (Roll Cage)

Racing Chip
Sports Chip
Stage 1 Turbo
Racing IC
Racing Brakes
Triple-Plate Clutch
Racing Flywheel
Carbon Shaft

Transmission:
Full Customize, set to general level 7

Suspension:
Racing
Spring Rate Front: 14.2
Spring Rate Rear: 8.0*
Height: 80mm F/R
Bound: 5 F/R
Rebound: 7 F/R
Camber: 2.0/1.0
Toe: 0/0
Stabilizers: 7/1

*I will just change the rear spring rate in order to control the experiment

I am doing practice runs on Tsukuba. We'll take the final large curve before the finish line for example.

Rear spring rate set to lowest (5.0). Build up speed to 6th gear/120mph right before the turn. Let go of gas and turn into right, my car's simply sliding into the turn. Add gas, the car spins even more.

Rear spring rate set to highest (14.2). Build up speed to 6th gear/120mph. Let go of gas, turn into right, I slide off the track and into the wall.

So from my experience, setting rear spring rate to lowest causes huge amounts of sliding, and to the highest keeps it extremely stiff. So if I were to just go about saying this, I'd say stiffer rear increases understeer (since I'm crashing into a wall).
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Firstly, I've done some testing using the variables you suggested, and also took a few liberties of my own, just out of curiosity. But I gotta say: taking this car into the final curve of Tsukuba at 120 mph, it's impossible not to have some negative behaviors taking over.

MY first instinct was to immediately brake. Correct me if I'm wrong, what you're describing, you're not braking at all, you're just steering-in and trying to add throttle at some point. Am I right?

1). Firstly, I did the curve as close to 120 as I could, with minimal rear springs (5.0, as suggested). The rear would break, just as you described. It happened fast and although I never got into a full-spin, I did lose control with these settings at this speed.

2). Did the same curve with maximum rear springs (14.2). The Nur slid off-track nose-first, just as described.

3). Tried using 8.0 in the rear. The car still understeered into the turn, but not as drastically.




OKay, I'm not liking the stabilizer settings: 7/1. It's like the front-end is mostly inflexible, while the rear is allowed lots of independent movement side-to-side. Matched with minimal rear springs, just imagine what is happening: the rear-end is allowed to rock side to side, while the front stays more planted and solid. This could be pulling the car (from the rear) out of its adhesiveness.

I tried putting the roll bars at 4/6 and retried the curve

1). With minimal rear springs (5.0), the car still oversteers, but (to me) felt more controllable. It wasn't as much of an ON/OFF feeling. The car didn't lose adhesion at the rear anymore, instead it merely needed a moment to get re-adjusted.

Really, what's happening is the front-end starts grabbing so FORCEFULLY when the gas is off and the car is steered-in. It's very aggressive lift-off oversteer, basically.

2). Tried max rear springs and 4/6 anti-sway bars. Yuck, I didn't like this at all. The car would merely understeer off-track.

3). Finally, tried your setting of 8.0 rear with 4/6 stabilizers. I liked this the best. The car grabs-in just as it did with minimized rear springs, and the rear starts to swing out. But it's (overall) the most controllable.


So overall, I see what you're saying. Those tuning guides don't get it all 100%, but keep in mind they are merely guidelines, not set-in-stone rules.




In any case, I'm sure there are plenty of tuned R34s out there. I just want to make the perfect line car; no understeer, no oversteer, just good for turning into lines.
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Hee haa hee ho ho! "Perfect" and 'GT4?" :lol: Yea, I'd like a Swedish blonde serving me Cuba Libres while I test people's cars! :lol:

More seriously, what you're asking for here is impossible. Gotta ask, are you really expecting to take the final curve at Tsukuba with no brakes? I found that when I followed my instincts, and braked into the turn, I could get the Skyline as balanced as it was going to get. But it was never perfect. :indiff:

Those super-soft tires make everything so herky-jerky: the front IMMEDIATELY grabs once throttle is off, for instance.. Couldn't really drive the car smoothly, or completely neutrally with these tires.

Also, why is everything moderated (even quick replies)... first forum I've seen doing that.
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Moderated? Not sure what you mean.
 
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In GT5 I had the same confusion.

After two simple experiments, I learned what the "Spring Rate" does. It is, in fact, opposite of what some guides say online.

Method:
Buy a 4WD car
Set Front "Spring Rate" lowest, and Rear Spring rate highest
Play a lap on Rome track
Watch replay, go to "photo Mode" during a tight corner
Physically observe the effect

Then, I did the same method, with the front at the highest , and rear at the lowest setting

RESULTS:

"Spring Rate" to a low value results in a "stiffer" spring

I think Polyphony meant the opposite of spring rate, meaning, the "compliance"

Peace
 
Yep, I've also found that sometimes stiffer rear = understeer.

porlino87
Physically observe the effect
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Hi Porlino, could you please explain what you mean by this? A few guys here like to watch the suspension in video replays, but how do you analyse a static photo?

porlino87
"Spring Rate" to a low value results in a "stiffer" spring

I think Polyphony meant the opposite of spring rate, meaning, the "compliance"
Click to expand...
I've checked this in the past by driving at bumpy tracks, over grass etc. In my opinion, higher is definitely stiffer when it comes to bump compliance. But like has already been said, the effect on grip balance doesn't always follow the "textbook rules".
 
In case no one has thought of this, having a softer rear suspension allows somewhat of a dynamic shift forward onto the steering tires (hence the oversteer), but moreso, it reduces the weight load on the rear tires (as Rotary Junkie pointed out). It's like lift-throttle-oversteer, in essence.

Having the stiffer rear springs means that the rear wheels are kept more firmly planted to the road, and if the forward springs are equally stiff, less dynamic weight shift is allowed. The car understeers.
 

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