740i alginment issues - keeps pulling to the right

[Frankie]

Hi racer,

I hear what you're saying. It'd be great if all the OP needed was new front tires. But in my world, that sounds too good to be true. And I still don't understand how new front shocks will rectify an out-of-spec front caster. I'd suspect strut mounts first.

Nevertheless, the pulls-after-alignment problem sounds eerily familiar to my experience, which had nothing to do with tires. Is it possible the OP's front tire came apart? Sure. But it's unlikely. More likely to me, something caused it to fail. Yes, the OP's front caster numbers are equally out-of-spec and logically that shouldn't cause a pull. Yet my front caster numbers aren't equal but they're in-spec -- with no pull. It's weird.

The bottom line is the OP's front caster spec is out. Correcting this resolved my issues, and I've got the tires to prove it.

OP: Hopefully you're done. If not, my suggestion may help. Time will tell.

[oldroller]

Pretty close to the nail Racer. A vehicle with uneven caster will pull, and the pull is always to the side with the least amount of positive caster. Exactly why I aligned
vehicles in areas with heavily crowned roads with a little more positive caster on the right side.
Think bicycle forks... vertical forks would be zero, and you'd be on your ass soon. So with the axle ahead of the post, positive, tracks straighter. Also why choppers
of the day drove like crap...wouldn't turn.

But more likely than not, a pull resulted from a tire issue. Sometimes hard to pinpoint, moving them around is an easy diagnostic tool. Unless the car in question has been wrecked/damaged in some way. Seen it hundreds of times during my wrenching days.

Glad you worked it out, mmiss2006.

[nmlss2006]

Frankie,
I am afraid I don't agree: geometries were not changed. Tires were. The problem went away.

Furthermore, there is no cross-caster, it's even, just low. Because of the way McP suspension works, cross-caster would have to be really significant to cause this kind of pull - and even then, the pull in a straight line with even pavement should be less and the amount of pull should be realated to speed. Here the pull was significant even at a standstill and did develop rather suddenly. There was some kind of failure - the previous pull was dialed out by alignment shop #2. The last alignment shop, by the by, was adamant about this being the case and did, as I mention, say that it was more common than he would have liked with that particular brand of tire.

I did read your thread and agree with racer again: the shocks at 130kmi are .. very done (with the roads here and the way stock shocks are, you'll be lucky to get 60kmi out of them) and the camber/caster plates should not be necessary. Also, 6.0 degrees of caster and 0.3 degrees of front camber is not how I'd like my car to be set up.

racer, you're correct: since when I bought this car as my SO's new commuter, June last year, it has had low caster as I mention above. It has been measured by the various shops as anything between 4.9 and 5.3, but it has invariably been even on both sides. It's been consistent for just under 20kmi and hasn't changed with the new control arms.

It does stand to reason that the reason why is the strut or the mount - though were it the mount, I'd expect more unevenness and poorer driving. Mind you, even now, the car does not drive like these did in 2001, but it has all sorts of tires on it - one with at least one missing balance weight - and the struts are very, very done. I need to change them... probably next month. The fronts don't concern me but the rears do - both at the top and the bottom - and I simply don't have time before then. Come spring, I'll also put Sumitomo HTR-Z IIIs on the 18s, which should fix the rest of the problem. Until then, I'll have the 16"s with winters which hide a multitude of sins.

I will keep everyone updated and I am grateful for the advice and opinions.

[tomloans]

I just wanted to add to this old post. My car was pulling to the right pretty hard as I couldn't take my hand off the steering wheel. My alignment was nearly perfect. I had 5 year old tires on my car with lots of tread left. Over 50k miles on the tires but they looked great. I swapped them and on cue the car then pulled to the left. One or both tires were having a problem. You can't tell by just looking at them. Both tires had the same 40 PSI pressure. I swapped them out today with fresh new tires and the problem is solved. Don't rule anything out.