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Old 04-30-2004, 03:23 AM   #1
rex n effect
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Default Does toe out in the rear reduce overall grip?

I know a lot of people like to have some toe out in the rear to aid in "rotation". Does that mean it reduces grip in the rear? Why would you want to reduce overall grip just to loosen up the rear end? Wouldn't more swaybar or a little less camber be a more tire-friendly option?
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Old 04-30-2004, 01:00 PM   #2
Back Road Runner
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If you look at it in a basic sense, toe-out in the rear will essentially "steer" the rear outside tire outward, thus making easier car rotation. I personally don't think it's the best option: wear, high speed stability, etc. You're trying to make the rear end come out, but it should probably be done another way: stiffer rear springs, stiffer rear sway bar, different tires, even technique changes.

As far as your main question, toe settings don't change grip in the basic sense. It changes the way the tires track. Around a corner, you'll put a lot of weight on the outside tires. With rear toe-out, the outside rear tire will want to track towards the outside of the corner. Sure the inside rear tire wants to track to the inside of the corner, but the outside rear tire has the weight and thus grip advantage. It's like being able to steer the rear end of the car in a way. Toe-out will help rotation by "steering" the rear of the car outward around a corner. Rear toe-in will help keep the rear end from sliding or drifting out by "steering" into the corner a little bit.

Toe-out helps steering and car rotation but makes the car want to wander more when straight.
Toe-in helps straight line stability and keeps the car centered, especially at high speeds.

This is true for both the front and the rear.

I'd personally go a different route if I was trying to get the rear end to come out easier. There are other ways that won't affect high speed stability.
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Old 04-30-2004, 07:21 PM   #3
Mark Avery
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>Why would you want to reduce overall grip just to loosen up the rear end?

Understeer means the front runs out of grip before the rear. Making the rears lose grip at around the same time as the fronts is how you get a neutral car.

Toe out to help the car rotate is useful in tight corners, like in an autocross, but as has been said, it makes the car less stable at speed.
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Old 04-30-2004, 08:21 PM   #4
Concillian
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A larger than stock sway bar reduces grip in the rear but increases overall grip.

It's all about balance and the conditions of the turns. Adding toe-out may increase overall grip, and may decrease overall grip. It depends on the turn in question and what the setup of the car is.

There are also subtle differences between the various ways of changing grip. The car is under a different set of circumstances entering a turn (front heavy) than exiting (on power, weight is in the rear now) Different adjustments will yield different results for different parts of the turn. I don't pretend to know how each part plays a role specifically, but you can bet that you will end up at a different result from reducing rear grip by increasing swaybar size vs. say increasing rear camber (less negative is increaing)
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Old 04-30-2004, 09:07 PM   #5
markus
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I have been using an alignment with a very little toe out in the rear for two years now. There is a noticiable different in how the car rotates, especially at the autocross course.

As has already been said, in theory, it is less stable at speed, but on my alignment, we're not talking huge numbers here (around 0.05degrees, according to my alignment printout).

Depending on your suspension set-up, I think a little toe out in conjunction with adjustable struts (or coil overs), and an adjustable rear sway bar, will allow you to really dial in your car for the type of driving that you do.

FWIW, IMO the handling advantages of small amounts of toe out vs no toe are a no brainer. But I like my car set-up so that I can rotate it on demand and in a predicable manner. Toe out is one of the ways that I can acheive this.

My 2 cents.

Cheers,
MB


PS I run the same alignment 24/7/365, even during our lovely Canadian winters, and I have no problems (and my rear sway bar set at 24mm) on snow/ice covered roads.
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