gtimax 發表於 2011-9-16 23:12
bump steer /ackerman no any relationship when I was tested.
but thanks
It's true that both of them may not have direct relationship but they are certainly affecting the toe change during cornering. Bump steer - something is undesirable, uncontrollable in 1:1 racing car and ackerman is something you can control and set to your desired level.
I'm just guessing .... (correct me if I'm wrong)..... you were tested at JV, a very smooth and flat track, excellent for touring cars. Under this circumstance with the ackerman being left as the factory setting, changing the bump steer (I here assume toe up when pressing down the front of the car) means having more toe out during the mid-corner and corner exit. Why not the corner entry, similar due to that the loading of the front tyres are controlled by the shocks, front roll centre height and the geometry of the suspension arms. At the mid-corner and corner exit, when these factors are pushing to the limits, the bump steer effect kicks in especially at the front inside tyre. The extra toe out at front inside tyre generates more lateral grip and therefore the car can have higher speed through the mid-corner and corner exit.
So why did you have more stability at the rear part? I can only assume (or another wild guess,  ) with the front part of the car (both the front outside and inside tyres are generating similar grip, instead of the outside tyre grip >>>> inside tyre grip), now the car behaves as if what a 4WD should be. Meanwhile, beware that you find the stability happened at mid-corner and corner exit, this is usually the area when you press onto the throttle so the weight transfer effect at your car put great loading to the rear of your car leading to excellent traction. Again, that means you would have no problem in accelerating your car out of the corner. |
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