Track car alignment

[r lane]

1978 911 SC track car with turbo rear arms. On my last 2 events I have lost my rear camber setting. I set it at 2.25* negative and back in the shop after the event it is between 1.5 and 2.0. Sanders torsion bars. I am assuming my securing bolts are not doing the job so will mark them on this go around to see if that is where it is happening. Thought about pinning it in a couple of places if necessary. Any thoughts and experience would be appreciated. Thanks, Bob

[Driven97]

The two bolts from the spring plate to the arm AND the cam bolt would have to slip which seems... excessive to me. Maybe post this in the track and AX section of the forum for better visibility.

[Mahler9th]

Common occurrence in some applications. Camber eccentric can rotate. Easy and inexpensive to prevent.

Check out this thread:

Rear Camber Adjustment

See my posts #27 and #29.

Once the toe and camber values are achieved, you remove the toe adjustment eccentrics. You then use appropriate bolts, nylocks and washers in its place.

On the outside, you use conventional washers under the head of the bolts. On the inside, you use large OD washers with some thickness and a notch or two of different depths. A common 911 shock washer will do. You just need something with a reasonable OD and reasonable thickness.

You can make 1-3 different notches with a grinder or any tool you have on hand. Even a flat or round file will do.

The keys:

The notch you pick goes against the camber eccentric and prevents it from rotating.

If the inside washer OD is suitable, it can and will deform as the bolt/nut are tightened.

Voila: you have now created a simple $1 locking mechanism that prevents the camber eccentric from rotating.

This is an old school trick taught to me by a former IMSA driver/mechanic/friend.

[Mahler9th]

By the way, my application has been racing. My tires are 16 inch diameter slicks.

14 inches wide-- big loads.

I have used this method for at least 15 or so years.

My car now has inner pick up boxes and the excellent Eisenlohr Racing Products rear spring plates. So I can adjust camber and toe more easily than a stock set up. But I still use this method to lock in the camber eccentric.

And I make sure the other trailing arm to spring plate bolts, nuts and washers are in good shape.

[Dan J]

I would endorse what Mike says and would add that I always replace the bolts clamping the spring plate with high quality 12.9 bolts and stover (metal) lock nuts which I torque ( 135nm 99ft/lbs) to spec and then some .Tighten the sh$t out of em

[Mahler9th]

I have not needed anything different from factory HW... and at time have used nylocks without issue.

But it cannot hurt anything but one's pocketbook to use "stronger" HW.

I do not use a torque wrench.

I do make sure that the HW is in good shape.

I have NOT had the experience of my rear suspension "falling" due to camber eccentric rotation. I have friends that have had it happen. It cannot be any fun to deal with this situation in the paddock at a race track.

I have been doing trailing arm car alignments in my garage since around 1993 or 1994. First on 951 cars, then since 2002 on my 911. I have many hours of experience adjusting rear camber and toe, and I have learned a few tricks.

It can be rewarding and can save money to DIY-- not sure I would have bothered for a street car. But for my racing application, it has saved me a LOT of money. It can take 6-8 hours to align and corner balance a trailing arm 911, even with coilovers. That can add up quickly if the shop rate is $100-200 per hour.

[r lane]

Marvelous, to para phrase the King, thank ya, thank ya very much. I have an Elephant racing rear bar set up whose links tie into the toe adjuster. That will require a work around, but realizing you need a door stop for the camber eccentric is of course the solution born out by all of youse guys experience. Thanks for the info, Bob