unstable at high speeds
11-15-2016, 11:24 AM
#1
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unstable at high speeds
I did an alignment when i put my KWV3 coilovers on, it is lowered about 1.5-2.0 inches and its pretty stiff all the way around. My question is that when i reach for example 120mph+ the car feels unstable and feels like its about to spin out, i can be holding the steering wheel as straight as possible and it just starts to wobble side to side making it unstable at really high speeds. I am running 18x9 42 offset all the way around with 255 35 in the rear and 225 40 in the front, but it was also doing the same thing when i had the stock wheels on. if i'm not mistaken it has to do with the alignment because i think my alignment settings are more for track but i never track the car, I'm really just looking for straight line stability at any speed. My alignment is Caster maxed out in the front if i'm not mistaken its somewhere a little more than 7, camber is -1.7 front and 2.7 Rear, Toe is 0.00 up front and 0.08 each side on the rear which equals up to 0.16 total toe in the rear. Steering response did increase a little more when i put 18's on, but i've gotten used to it. Do i need to buy anything so the car can be more stable at high speeds, do i need to change my alignment specs? Any help would be great. Thanks.
11-15-2016, 01:39 PM
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I don't do 120+ regularly its just whenever i do it starts to get a little unstable. I think it has to do with my alignment. Never used to do it when i had stock suspension
11-15-2016, 01:48 PM
#4
Did you change your tires since stock suspension as well? What tires are you on now? Alignment looks good pretty good, but a little less camber in the rear wouldn't hurt if possible. -2 would be good. This isn't the most stable car at those speeds even if everything is correct. Its a short wheel base car. But it should still not feel like its going to spin out if you make course correction at those speeds like you would at most any track environment. Tire construction is crucial on this car for proper handling. You need to have a 2 ply sidewall, and firmer the better. Sidewall deflection amount along with alignment is the biggest factor in the handling of this car. If your lowered too much on the kw and riding on the bump stops, that can be working against you as well. There are more inertial forces at play on chassis when at those speeds.
11-16-2016, 09:29 AM
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Did you change your tires since stock suspension as well? What tires are you on now? Alignment looks good pretty good, but a little less camber in the rear wouldn't hurt if possible. -2 would be good. This isn't the most stable car at those speeds even if everything is correct. Its a short wheel base car. But it should still not feel like its going to spin out if you make course correction at those speeds like you would at most any track environment. Tire construction is crucial on this car for proper handling. You need to have a 2 ply sidewall, and firmer the better. Sidewall deflection amount along with alignment is the biggest factor in the handling of this car. If your lowered too much on the kw and riding on the bump stops, that can be working against you as well. There are more inertial forces at play on chassis when at those speeds.
Last edited by kenneth_1010; 11-16-2016 at 09:35 AM.
11-16-2016, 12:53 PM
#7
40-42 psi seems very high, running on inner tyre too much with that amount of camber,
lower and re test for an improvement 32-34
lower and re test for an improvement 32-34
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11-16-2016, 12:58 PM
#8
Lower pressures to 32 cold. If that doesn't get you there, reduce rear camber to -1.5. You didn't say what measurement type you're using for toe. If it's degrees, you're running very little rear toe-in and that will make the car less stable.
And lastly, the stock S2000 has rear aero lift, so the faster you go the less rear grip you'll have available.
And lastly, the stock S2000 has rear aero lift, so the faster you go the less rear grip you'll have available.
11-16-2016, 02:58 PM
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Lower pressures to 32 cold. If that doesn't get you there, reduce rear camber to -1.5. You didn't say what measurement type you're using for toe. If it's degrees, you're running very little rear toe-in and that will make the car less stable.
And lastly, the stock S2000 has rear aero lift, so the faster you go the less rear grip you'll have available.
And lastly, the stock S2000 has rear aero lift, so the faster you go the less rear grip you'll have available.
I'll lower the tire pressure to 32PSI and see how that goes, if not I'll see if I can lower camber to -2 in the rear, as far as toe I'm running 0.08 degrees on each side which leads to 0.16 total toe, how much total toe should I run in the rear?
11-16-2016, 03:17 PM
#10
I assume you meant rear camber is -2.7 correct ?, seems a bit high to me but the instability must be toe related. You have .16 total rear toe in , make sure it wasn't done as toe out. I would have a shop double check your settings in case something loosened up. Running a bit more rear toe in can give you more stability on the street.