Joe Weinstein

Hi all. I am told stories about 996s not keeping an alignment very long
under race conditions. Assuming the alignment shop does race cars,
and tightens things assertively, how long should I expect to keep the
settings reasonably close? The car is a full-weight car, and isn't driven
over horrible roads, but is street-driven to-from... Are there any tricks
or parts that will nail down the alignment more durably, or is this all
hog wash?
thanks
Joe

Larry Herman

I have aligned 2 GT3s for the track, my old one and my friends. Both are/were driven on race tires and neither lost their alignment, even when pounded over the curbs at various racetracks. I think that if the rear eccentrics are properly tightened, and it's a bitch to get them really tight, then they will hold just fine. Once the knurled surfaced gets stripped smooth because they have slipped, they will no longer hold a setting and you need to change to a turn-buckle type arm, like the cup cars have, IMHO. To answer your question more directly, I would say that the alignment should hold for the season.

trackjunky

Larry, might this be a potential safety issue the PCA club racing should consider? If alignments change drastically on the track, bad things could follow........no?

JimB

I agree completely with Larry that you need to replace the eccentric bolts on the rear when they get worn down but realistically it's takes a long time and is an easy fix. I don't see a safety issue. Normally the car holds an alignment just fine.

There is a safety issue with the rear ball joint bolts on the 996 though. That's why there's a proposed rule to allow GT3 control arms. I really hope it passes.

trackjunky

So after the eccentric begins slipping, changing to a new one solves the problem?

fly2low

Question. How about adding rear toe links instead of the eccentrics?

mpaton

I don't believe it's the function of the eccentric to hold alignment at all; it's just there to alter the pivot point of the lower track control arm and the toe control arm while the alignment is being performed. However what DOES happen is that some people who do alignments don't have the 18mm S-shaped ring wrench that you need to tighten up the eccentric bolts properly, and so they improvise, and the result is that these bolts aren't tightened correctly and the rear toe and or camber changes, sometimes drastically. Pretty sad when Harbor Freight sells them.

Michael

JimB

I aligned my car dozens of times while I raced it for four years before it started slipping a little bit. Just replacing the bolts fixed the very minor problem for me. It really is a non issue.

Larry Herman

Michael, that is exactly what they are supposed to do. They move the pivot point to set the alignment. Once you tighten them, they should hold that position.
And that is why they don't, because they are not tightened enough and they slip.

JimB

What I think happened to us is that we stretched the bolt over and over until it no longer torqued properly and loosened on it's own. Does that make sense?

Larry Herman

Yes it does. The eccentrics can move when a high lateral force is applied to them if they are not tight enough. Bolt stretch will cause them to be less tight than they should be, and so they could move. I had a set of regular adjusting eccentrics for front MacPherson struts move because I had them incorrectly torqued to 90 ftlbs. The proper value was 140 ftlbs, and when I tightened them to that they no longer moved, even with track use.