i have an oversteer problem
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i have an oversteer problem
I have stance coilovers, set 6 or 7 clicks rear, full stiff front, 265(f) 285(r).
Hotchkis sways again full stiff front, full soft rear, One would think that with this combination i would be an under steering monster, but i am not. I think the problem might be that I have equal camber front and rear set to (1.7-1.9). Why is this happening to me? I desperately need help with this.
Hotchkis sways again full stiff front, full soft rear, One would think that with this combination i would be an under steering monster, but i am not. I think the problem might be that I have equal camber front and rear set to (1.7-1.9). Why is this happening to me? I desperately need help with this.
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From: Albany, GA
There are two types of Oversteer: Trail Throttle Oversteer or Power Oversteer. Which one do you have?
I would first look at your tires, your rear tires could be your problem. Next, look at your front and rear wheel rates and see if it is a spring problem. Then I would see if anything is binding in the suspension. Then I would then look to see if you are bottoming out your suspension. Also, look at your LSD, having to much lock up on deacceleration could cause this. Finally ask yourself if it is an operator error, either braking to late or applying to much throttle.
I would first look at your tires, your rear tires could be your problem. Next, look at your front and rear wheel rates and see if it is a spring problem. Then I would see if anything is binding in the suspension. Then I would then look to see if you are bottoming out your suspension. Also, look at your LSD, having to much lock up on deacceleration could cause this. Finally ask yourself if it is an operator error, either braking to late or applying to much throttle.
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Its not an operator problem. How do i check for binding? The rear tires are balding but still have some tread.....spring rates should be good they are stance coilovers, all stock springs. Its just general oversteer. I know how to ballence a car with trail braking or power over. Im not doing either, Im keeping constant and very gradualy increasing throttle all the way through the turn. The rear just allways breaks first. Could it be the camber. Im not bottoming out the suspension either.
Something else, dealing with your starting point.
The Stance setup does run a lot more rear spring vs other coilover setups because of it's true coilover setup leveraging greater amounts of spring to the wheel. My trial and error testing agree's with the Unitech race teams findings in R&D research for the Truechoice setup. Though we are ALL supposed to do our own proof of concept testing.
Wheel rates
Stance
335/280
Jic
335/241 (10kg/12kg setup)
Ohlins, Zeal, or anything running 10kg/8Kg
279/161
Truechoice/Unitech
262/153
IMO, since the Stance setup is valved for 2Kg changes front and rear, I would lower the rear spring rate by 1 or 2 Kg and test.
The Stance setup does run a lot more rear spring vs other coilover setups because of it's true coilover setup leveraging greater amounts of spring to the wheel. My trial and error testing agree's with the Unitech race teams findings in R&D research for the Truechoice setup. Though we are ALL supposed to do our own proof of concept testing.
Wheel rates
Stance
335/280
Jic
335/241 (10kg/12kg setup)
Ohlins, Zeal, or anything running 10kg/8Kg
279/161
Truechoice/Unitech
262/153
IMO, since the Stance setup is valved for 2Kg changes front and rear, I would lower the rear spring rate by 1 or 2 Kg and test.
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From: Albany, GA
Taking those wheel rates, I would go with a softer spring in the rear and test just like Gsedan35 suggested.
To see if the suspension is binding, I remove the wheels and coilovers and then move the suspension by hand. I then remove all suspension linkages and look at the bushings and test each of the bearings to see if they have a "hot spot". Finally, I look at the linkage to see if it has been bent or fatigued. This takes time but I do this on an annual basis (or after an endurance race). If you track your car all the time you must treat your car as you would an airplane.
To see if the suspension is binding, I remove the wheels and coilovers and then move the suspension by hand. I then remove all suspension linkages and look at the bushings and test each of the bearings to see if they have a "hot spot". Finally, I look at the linkage to see if it has been bent or fatigued. This takes time but I do this on an annual basis (or after an endurance race). If you track your car all the time you must treat your car as you would an airplane.
I also think the Z is a car that tends towards oversteer with a square tire setup. General philosophy is to balance out a car with springs. I don't know anything about stance coilovers, but I will say that I've yet to run a kit that comes with springs that suit my car setup / driving style.
Initial impression would be to get yourself some softer rear springs or stiffer front springs. However, if you truly do have a travel issue, than this can do more harm than good. I would put some zip ties on your shock shafts. If they are pushed all the way up inside the bump stops after a lap (being sure not to hit any burms), you've got a travel issue. Softening rear springs will compound the problem in this case.
You also need to think a little bit more about when the car oversteers. Is it corner entry, mid-corner, exit, or steady state? And what is the weight balance of the car when the oversteer occurs. Do tire temps play a part (ie early in the session or late in the session).
To sum up; think long and hard about the circumstances of your oversteer, and be very methodical about the remedy.
Initial impression would be to get yourself some softer rear springs or stiffer front springs. However, if you truly do have a travel issue, than this can do more harm than good. I would put some zip ties on your shock shafts. If they are pushed all the way up inside the bump stops after a lap (being sure not to hit any burms), you've got a travel issue. Softening rear springs will compound the problem in this case.
You also need to think a little bit more about when the car oversteers. Is it corner entry, mid-corner, exit, or steady state? And what is the weight balance of the car when the oversteer occurs. Do tire temps play a part (ie early in the session or late in the session).
To sum up; think long and hard about the circumstances of your oversteer, and be very methodical about the remedy.
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Originally Posted by Drift_corners
Its not an operator problem.
Originally Posted by daveh
You also need to think a little bit more about when the car oversteers. Is it corner entry, mid-corner, exit, or steady state? And what is the weight balance of the car when the oversteer occurs. Do tire temps play a part (ie early in the session or late in the session).
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From: CT
The Z is so nose heavy that the car should plow unless the suspension was modified to make the car more tossable. I have seen the poster's car in acton, the car looks like it has the tendency to snap.
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it happens mid corner, corner entry if fast enough, and exit under power. THERE IS NO WAY TO PRODUCE UNDERSTEER, unless i am turning very tight on an autocross. over 40 MPH it wont do anything but oversteer. i don't have $ for springs so ill start by fixing the rear camber and lowering the rebound. TMAK the car is pretty progressive when it goes, but when i autocross i tend to toss the car too much. I drive the autocross like a rally, apposed to when i stick to the smooth and steady method on the track.
Although this is probably not the case here, its something to think about when trying to figure out an "oversteer" problem:
Most people "think" they have an oversteer problem due to horsepower when they really don't. The real problem is understeer and the driver's right foot. Here's what happens:
1. At the threshold just below where the rear tires break traction due to engine torque, the car will generally be pushing pretty bad due to weigh transfer to the rear.
2. To compensate the driver has put in a lot of steering to get the car to turn.
3. The driver then thinks - "More power will reduce the understeer by breaking the rear tires lose."
4. Drive adds power.
5. Rear tires break traction.
6. Weight transfers forward increasing front grip, reducing rear grip, and the understeer goes away.
7. Because of the extra steering the driver has put in to compensate, the front of the car darts in the direction of the steering due to the new found front grip.
8. Rear tires are now sliding in the opposite direction as the fronts.
9. Driver's hands are not fast enough to catch the spin.
10. Driver gets scared and lifts off the throttle.
11. More weight transfers forward, increasing front grip and reducing rear grip while the chassis is rotating. This increases the the rate of rotation.
12. Car goes past 90 degrees and driver is now countersteering the wrong way.
13. Spin...
1. At the threshold just below where the rear tires break traction due to engine torque, the car will generally be pushing pretty bad due to weigh transfer to the rear.
2. To compensate the driver has put in a lot of steering to get the car to turn.
3. The driver then thinks - "More power will reduce the understeer by breaking the rear tires lose."
4. Drive adds power.
5. Rear tires break traction.
6. Weight transfers forward increasing front grip, reducing rear grip, and the understeer goes away.
7. Because of the extra steering the driver has put in to compensate, the front of the car darts in the direction of the steering due to the new found front grip.
8. Rear tires are now sliding in the opposite direction as the fronts.
9. Driver's hands are not fast enough to catch the spin.
10. Driver gets scared and lifts off the throttle.
11. More weight transfers forward, increasing front grip and reducing rear grip while the chassis is rotating. This increases the the rate of rotation.
12. Car goes past 90 degrees and driver is now countersteering the wrong way.
13. Spin...
Originally Posted by Drift_corners
i don't have $ for springs so ill start by fixing the rear camber and lowering the rebound.
Disconnecting a rear sway bar, or putting the stock bar back on would have similar effect to changing wheel rates (and they're free). Lowering the rear would also be a free thing to try (if you have adquate shock travel).
Have you taken tire temps?
All great suggestions, but have you checked your alignment?
If you've been playing w. your ride height then you've changed the toe (front and rear). It is very possible you've got a little bit too much toe-out at the back than you'd prefer.
If you've been playing w. your ride height then you've changed the toe (front and rear). It is very possible you've got a little bit too much toe-out at the back than you'd prefer.
Last edited by THX723; Aug 3, 2007 at 09:15 PM.
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From: Albany, GA
Originally Posted by Drift_corners
Its not an operator problem. .
This is one of the first questions I always ask myself and if I can't answer it, I ask someone I trust to sit in the passanger seat and see what they think. It is far easier and cheaper to fix the operator than change the set up on the car.
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i acualy am going to change my name to grip corners. so thats me now. And i might try putting on the stock rear bar, Id feel wastfull but ohh well. I have plenty of wheel travel i made sure that i made a track ride height not a street / show on.
Should the stock rear bar fix the problem is the car going to be "Strange" or not optimum if i have a super stiff front and stock rear
Should the stock rear bar fix the problem is the car going to be "Strange" or not optimum if i have a super stiff front and stock rear