Do it youself alignment woes

Aligned the car myself. First time. Everthing seems good except I notice when either of the rear tires hits a fairly deep manhole cover the car does a little shimmy to one side. This isn't on a turn, but on straight road. Happens if either drivers or passenger side rear tire hits. Not sure which way it shimmy's because it happens so quick. I would think this would be a symptom of rear toe in or out. but I don't have any. Might be because the rear toe (set to 0 degrees) isn't centered on the car. Anyone now any tricks to ensure the rear toe is centered on the car. This is the only thing I can think of. The tack in the tire / plumb bob method doesn't guarentee that the toe is centered on the car. Anyone have any ideas what else it could be?

Alignment is set as follows:
Car is lower than euro spec by 1/2"
Rear camber is set to about neg 1-1/4 Dergrees. Rear toe in is set to 0 degrees.
Front camber is neg 1/8 degrees
I don't know what front caster is because I don't know how to check it.
Front toe in is set to 1/8 degrees.

Thanks guys,
Leon 78SC

You might have it set so low that your shocks a bottoming on their stops.

Reducing the amount of front toe to zero or slightly out could help stability.

Regards,

Joe

Leon,

Are there some typo's in your specs?

Is your front toe-in 1/8" or really 1/8 degree?

Is your rear toe-in really zero? If it is, that is most likely the source of your 'twitchiness!' You need some rear toe-in, 10 minutes of angle is recommended by Bruce Anderson, for directional stability.

------------------
Warren Hall
1973 911S Targa

Thanks,

Yes that was a typo. It's 1/8 degree.
I'll try 1/6 degree toe-in in the rear, and same of toe out in the front. Shocks aren't bottoming out. Let you know what I find. I failed to measure from center of torsion bar cover to brake hub to check for equality on both sides of car. Hopefully I'll find they aren't equal, and I'll re-adjust.

Thanks again,
Leon 78SC

Well found out what it was. Turned out I was mistaken in saying I had no toe in in the rear. Actually had about 1-1/4 degrees of toe in. Don't know how I screwed that up. Set it to about 10 minuits as recomended and problem went away. Ready for autocross on sunday.

Thanks for the advise.
Leon 78SC

[mr.sbux]

It seems like you guys are adjusting the alignment, but I am not really sure how to do it.

Can anyone give some direction? I am new at rear wheel alignment. '87 E30/325 is wearing on the rear wheels and the rear wheels are kind of pidgeon toed (front of tire points outward) and wearing the inside edge of the tire.

Is there an easy (understanding time is required) to adjust it? I have help from a guy that does all the work on his own cars, but a rear alignment is not part of his repetoire of knowledge.

Please help.

Thanks,
Bryan