Z06-Nomad

I know it's "good" to have a little rear toe in, and "bad" to have rear toe out, but why exactly is this?

Thanks,

MD

wallyman424

toe out will make the rear end "squirrly," for lack of a better word. It will increase off throttle oversteer, and just make the rear end more likely to come around.

The little bit of toe in is good because when you start braking, the rear end raises, causing the toe to go out with the suspension travel. The initial toe in makes up for this, so that you dont go toe out during braking.

RAFTRACER

rear toe-out= undesirable 4 wheel steering

Z06-Nomad

OK. Thats a good start, but I was hoping for more detailed information... The braking part makes sense.

The 4 wheel steering doesn't make sense to me.
Once you are in a turn, if the rear tires are toed out the same amount, why don't they cancel each other out ? one would be pointed to the inside of the turn and one towards the outside...

"Splain" some more please...

MD

undertaker

that one is pretty easy, more weight on the outside tire, to the ***-end of the car is going to follow the line of the outside tire which has much more traction than the inside which is lifting somewhat

acrace

Z06-Nomad:


They wouldn't cancel each other out because the outside tire would be the loaded tire, due to the cornering force. So, if there's toe-out, that would lead to raftracer's "four wheel steer" comment - the rear will want to step out. High powered rear wheel drive cars magnify this condition because you would want to add throttle as you are exiting the corner, so with toe-out power induced oversteer becomes prevalent.

Toe-in is the usual design parameter, both front and rear, because with bushing compliance and the road force generated as the car moves forward, the natural tendency is for toe-out to be induced. So toe-in is used to counteract this. How much toe in becomes a function of the type of driving you do (highway? autocross? track events?) and the characteristics you desire.

XPC5R

In the real world, my experience has been rear toe in helps the car on power down.

1/8 to 1/4" toe'd in makes the the rear end very controllable on corner exit - oversteer while adding thottle is reduced, and what oversteer you get, recovers quicker, and is less severe. Makes for a nice setup for those who are aggressive wiht the throttle.

It can induce some additional low/medium speed understeer (because of the improved rear bite) so it must be adjusted to match your driving style and car setup. For example, I typically have 1/4" toe out in the front to limit undesteer.

speedjohnson

What they're all trying to say is that the rear tires don't stay straight when the car is loaded.

If your rear tires aren't traveling in a straight line, but rather, they are turning "out", then the rear of the car will want to "turn"... and will try to pass the front... and that is bad.

Toe-in slows you down some in a straight line due to drag from the slightly scrubbing tires, but overall makes for a stable straightline ride.

To a large extent the C4 and to a lesser extent the C5 will toe-out when the car sqauts when the power is layed down. This can be compensated for by setting the suspension with a little toe-in to start with... say 1/8 inch or so total toe-in when the car is aligned. This will scrub, and slow you down minimally, but will insure that your rear tires never go into toe-out when the suspension squats, or when you put that 500hp to the rear tires and the bushings stretch.

Z06-Nomad

Thanks to everyone that responded. It helped a lot.

MD