Alignment Questions

[Dan Cordon]

<snip>
> Two questions: what happens to make the suspension unable to accept more 
> negative camber? Do pieces get bent? Does the adjustment involve threads 
> that become crushed or ruined? I don't understand that part of the 
> process.

More than likely a piece(s) got bent. I'm less familiar with the 
80/90's, but on the Type $$ chassis the upper strut mount has slots in 
it that move the top of the strut side to side which adjusts camber. On 
Type $$ cars, you can grind out the slots a little more (~ 0.2") for 
more adjustment.

> 
> If I ask them to bring back my negative toe, is there anything wrong with 
> this request? Previously, the steering was quick and precise. I guess I 
> don't understand why he dialed in so much positive toe.

Having positive toe is likely the cause of scary driving. By nature, 
positive toe is unstable. Even slight weight transfer from side to side 
will enhance the steering in that direction. When putting new tie rod 
ends on, I've experienced toe out.....just as you describe....no 
confidence on keeping the car in its own lane. I'm unsure as to why any 
alignment specialist would recommend toe out. Anyone??

> 
> I am trying to balance between excess tire wear on the outside front right 
> tire (due to heavy cornering), and responsive steering.

The closer you are to neutral (toe and camber), the longer your tires 
will last. More negative on each will tend to eat the inside of the 
tires. But camber between 0 and -2.0° isn't excessive at all, and 
shouldn't hurt the tires much. You'll want just enough negative toe to 
make sure there's never any positive toe as components flex. I think 
it's usually less than a degree.

IIRC, the point to camber is to get the largest contact patch of tire 
when cornering. As bushings shift, and the tire rolls slightly, a tire 
w/o camber would be riding on the outside edge. You only need enough 
camber to correct for this. I know lots of kids with sport compacts that 
dial in *way* more camber than necessary. A good way to tell is to do 
some skidpad driving, then measure tire temps across the tire and see 
where it's hottest. If it's on the outside then you can dial in more 
camber. If it's on the inside, you've got too much. Different cars/tires 
require different amounts.
> 
> If you have any comments or suggestions for me, I'd appreciate it!

Did you get any numbers for your caster? It's not really adjustable on 
our cars, but by noting any difference from side to side, and comparing 
to the specs for the car, you may be able to ID bent components from that.

-- 
Dan Cordon
Mechanical Engineer - Engine Research Facility
University of Idaho