There are charts all over that tell you what effect changes will have on
handling. Such as a stiffer front sway bar decreases oversteer, etc. But I
have not found the result of the change I am interested in.
What effect will raising the front roll center have? No other real change to
the car. I was going to change springs and bas also, but I think that may
hide or obscure the primary change I am making.
The front roll center is going up about 2 inches. This is being done with a
thick shim, so the change can be reduced, if it is too drastic.
>From what I can find in books and on the internet, this will reduce the roll
torque, so the amount of body lean will decrease. This should increase the
weight transfer taken by the front wheels, whikle reducing the weight
transfer taken by the rear wheels. So this (I assume) will decrease oversteer
(or increase understeer) just like more front sway bar. This is on a rear
drive car, and I was lifting the inside rear tire off of the ground killing
traction at corner exit.
The basic balance was adjusted for a bit of understeer, but would go to
oversteer when the tire would go airborn. The transition between the
understeer and oversteer made it so when I had it dialed in for good neutral
balance with all the tires on the ground, I had to drive a bit under the
limit to run clean. I set it up with a bit more push, and was then able to
drive it harder, and would only get loose if I was way over my head, but I
know it was not the fastest.
My hope is that the tire will stay on the ground, and I can adjust camber,
toe, and if needed, spring rates to balance the undrsteer back out. I feel
the tire was lifting due to not enough rebound travel in the rear shocks for
the amount of body lean. The rear bar is very soft, and not able to compress
the spring with the other rear wheel at full compression. I now have almost a
full inch more rear droop travel by spacing the upper shock mounts lower.
This alone may go a long way to eliminate the transition, but should have no
effect on the raw balance of the chassis.
Front roll center was below ground by nearly an inch. It should end up just
above ground, I still have to measure it, the change is not done yet. The
roll center was lowered severely by lowering the car with short springs. This
change is going to get the roll center about halfway back to stock height.
Rear roll center was not effected as much from the lowering due to different
geometry, resulting in a rear roll center height about 3 to 4 inches above
ground. Front weight bias is only 52%.
I know everyone is going to ask, what kind of car, and what class. Several
people on this list know me, and my car. I will worry about legality of the
changes later. For now, I just want to make it work.
Gary M.
/// unsubscribe/change address requests to majordomo@autox.team.net or try
/// http://www.team.net/mailman/listinfo
/// Partial archives at http://www.team.net/archive
|