Lowered Suspension Stiffness = Greater Oversteer?

  • Thread starter Thread starter Maturin
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Maturin

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Need some help. The conventional wisdom on this board, and elsewhere, is that greater springrate or shock bound increases the tire downforce to that side of the car (i.e., higher springrate/higher bound in the rear = more oversteer or lesser springrate/bound = less oversteer). And less spring/bound in the front will decrease understeer (until it bottoms).

However, I've found the opposite. I bought a Supra RZ (FR), that has a default setting of:

Springs: 15.0f/7.5r (I could be off a bit by decimal points, but it's similar). This car oversteers like mad default (all ASM off). If I increase the rear stiffness to the SAME as the front, it gets rid of the oversteer and is neutral. Bound/Rebound were both at 8, and everything else equal, no camber. Shouldn't it get WORSE from an oversteer perspective?

I also tried doing the same with my DB9, and I can drift this with a 15/7 spring and oversteer like mad, but it understeers at 15/15, and at 10/20 it's an understeering train toward the wall. This effect also occurs with more modest adjustments.

And, yes, I know the difference between oversteer/understeer.
 
Your front end springs are WAY too stiff. Hard spring settings in front = less downforce on the tires from the weight of the car = less grip = lowered steering ability. You may be getting oversteer on the Supra because the soft rear settings are making it drift.
 
Softer rear suspension = greater weight transfer to the rear ... More weight at the rear during rotation = greater momentum of the rear end ... This means the rear end has a greater tendency to continue rotating, thus causing oversteer ...
 
So why is if I want to reduce understeer in a front driver I RAISE the rear spring rate and it works ? it works to the point of promoting oversteer at times. If too much weight shifts to the rear you unload the front wheels causing the rear to grip stronger than the front..that will cause UNDERSTEER.
its simple enough for any one to prove .
 
Softening the rear suspension will make the rear end "stick" more. It makes weight transfer slower from front to back, allowing the tire to work its way through the turn, without an immediate transfer of weight to the wheels. The harder your suspension is in the rear, the more prone the car will be to oversteer, due to the immediate weight transfer (thus causing loss of grip)

This is also the same (somewhat) for the front. If you make harder suspension up front, the weight will be shifted quickly, causing the tires to lose grip faster. Thus, you get understeer. Softer suspension allows weight to be transferred more slowly, giving the wheels more grip-time, and more time to turn before losing grip once all weight has been transferred. Softer suspension up front also promotes trail-braking.

Having a stiff stabilizer bar will also create understeer/oversteer the harder it is. Just thought i'd throw that in.
 
Acid X
The harder your suspension is in the rear, the more prone the car will be to oversteer, due to the immediate weight transfer (thus causing loss of grip)
Click to expand...


I'd love to know what car you're doing this to in GT4, because every car I have in GT4, if you stiffen the rear, the car UNDERSTEERS more.

Just out of curiosity, does everyone who seems to have a truly great understanding of real-life physics actually PLAY GT4?! It doesn't seem like it. It's a serious question, because Greyout seems to have not played it.
 
I race amatur autocrossing, in the SCCA. I know if you soften the front the car turns in better but that does not mean you can but spring with a value of 3 and it will drive good. The rear of the car is the same, dude with the supra needs a stiffer spring in the rear but not alot stiffer just alittle and lower that front sping too, Try 10 in front 10 in back, then slowly make adjustments trust me if the car is still overstearing on TURN IN give it an 11 in back. Hey if your spinning out of the corners the only thing I can tell you is we need a better description of how the car is reacting thru the corner. Check your sway bars should be about a 3 front 4 back. Unless the car weighs 4000lbs or has tons of downforce, no car needs over a 14 spring anyware on the car. If the car is really really light (under 1600lbs) mabye you might find a spring might need to be as soft as 5, but spring are suporting weight so weight is part of the equation for getting your suspention right. happy motoring.
 
In addition (i haven't played GT4 yet but from real world experience), by stiffening the cars suspension breakaway (transition of grip to no grip..) is more sudden.

-Rob
 
Maturin
I'd love to know what car you're doing this to in GT4, because every car I have in GT4, if you stiffen the rear, the car UNDERSTEERS more.

Just out of curiosity, does everyone who seems to have a truly great understanding of real-life physics actually PLAY GT4?! It doesn't seem like it. It's a serious question, because Greyout seems to have not played it.
Click to expand...

I have done it to my Buick GNX. After softening the front, and stiffening the rear, i noticed it was much simpler to oversteer.
 

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