1979-1993 & 94 Conv [Subscribe to Daily Digest] |
I'm gorper. Got tired of people writing "gRoper." Plus it's an esoteric term that almost no one outside of the backcountry skiing community gets. :-)
Your specs look fine. Basically, the idea is to get rid of the positive camber that Saab deliberately specifies to make the car understeer a lot (keeps drivers safe). Increasing camber puts more rubber on the road during cornering; this increased grip decreases the car's tendency to understeer.
The low toe-in settings are for increased steering response -- you sacrifice some straight-line stability for a front end that will turn in quicker. If the car is not stable enough for your taste, have a bit more toe-in added.
Caster adds negative camber when you turn the wheel off-center. (The drawback is some increased steering effort, a non-issue with power steering.)
Regarding dynamic toe change:
How toe changes depends, in part, on whether the car is a front-steer or rear-steer set-up: that is, whether the tie rods attach in front or behind the wheel center.
Saabs (most FWD) have a rear-steer set-up. When the car accelerates, the front end rises while the suspension droops, and the tie rods pull the wheels in toward each other in the back, and out and away from each other in front (AKA toe out). The opposite occurs on a front-steer set-up.
Why does the toe change? Because the tie rods run on an arc traveling up and down. They're already drooping down at rest/no acceleration, so when the front end lifts/suspension droops, the tie rods droop even more, shortening the linear distance between the rack and the spindle. This shortening pulls the wheels away from each *from behind* the center, toeing them out.
Saab specs toe-in from the factory, not toe out. Too much toe out will make the steering too darty and unstable, and will wear the tires' inner edges very quickly. Too much toe in will wear the outer edges too quickly.
If you are interested in learning more about vehicle dynamics, borrow Fred Puhn's "How to Make Your Car Handle" from the library, or buy it used from Amazon or half.com. It's a great introduction to this stuff.
posted by 67.183.141...
, Mon, 23 Oct 2006 14:18:45, Tue, 24 Oct 2006 13:29:46, Mon, 23 Oct 2006 16:53:24, Mon, 23 Oct 2006 17:51:44
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