Quote:
Originally Posted by george kujanski
T for better handling on an otherwise stock setup, what would be some good target numbers for caster, camber, toe?
|
MY philosophy with a stock- or near-stock suspension in good condition, is to shoot for negative camber, minimum toe, and all the positive caster I can get while keeping the camber negative.
HOW MUCH negative camber is up for discussion. So far as I'm concerned, the most-negative camber according to OEM spec is the most-positive I'd want.
In other words, if the OEM spec for camber is +2 to -1/4, I would want to be at -1/4 to -1/2, maybe as much as -1 depending on the suspension geometry and intended use. I don't get too worried about tire wear at 1/2 degree, I have some concern at 1 degree or more. If you're driving a grocery-getter, you look for maximum tire life. If you're looking for cornering power, some tire life gets sacrificed.
Remember, the engineers and lawyers DELIBERATELY sabotaged the handling of these cars when they were designed. They would build-in boatloads of understeer in order to absolutely prevent oversteer. Part of that was spring rates, sway-bar and tire sizing, but some of that was adding
too damn much positive camber. There's also the issue of dynamic camber change--tall and soft springs coupled to too-short steering knuckles leads to lots of body roll. Lots of body roll leads to positive-going camber change on the outside, load-bearing wheel, only some of which is removed as the outside suspension compresses on the turn.
Camber is a tire-wearing angle. It will also cause "pull". Caster is not a tire wearing angle, but also causes "pull"--but it takes twice the caster to pull as much as camber. Used to be, cars were intentionally aligned to pull slightly left. Roads were "crowned", so the roadway itself made the car drift to the right. Highway engineers are taking the crown out of the roadway in favor of humps and dips. I don't approve, but no-one asked my permission. Given a choice, I like to have a vehicle that will drift VERY SLIGHTLY to the right on typical roadways. Driver falls asleep, he hits the ditch instead of oncoming traffic.
IN GENERAL, a 1/4 degree difference in camber L/R, or a 1/2 degree difference in caster l/R was used for road-crown compensation. I'm not sure that much difference is needed any more as roads have less crown.
The trick is to get the camber where you want it, while maximizing positive caster. Positive caster makes for strong self-centering of the steering, and also increased steering effort--but these cars had way too much steering assist to begin with, so extra effort is a non-issue.
Then a minimal amount of toe especially with wide tires. Too much toe wears tires really fast, and makes for wildly unpredictable handling--twitchy, darty, won't-go-straight. With rear-wheel drive, toe-in partially compensates for worn steering joints and loose wheel bearings. If the suspension/steering is still "tight",--and it better be--you don't need a lot of toe.