Ok, 74 that has steering wheel shaking when reaching speeds of 55mph or more. I have changed the tie rods, struts, ball joints are good although I have new ones standing by. Front wheels are getting eaten on inside of tire. I wasn't able to check alignment due to the alignment tool was broken at the place I went, but they will have a new one in the next few days. I will take it back to recheck. Everything is tight and can't figure out why it is doing this, so far. Before I left we, rotated rear tires up front, but it still has the shaking, not as bad but there. Tires are dead on balanced and they are new. 4000 miles on on four.
What do I look for next?
Thanks for your input.

sounds like an alignment issue... I've had a bent rim on another car that would wobble at speeds, too... but I would check wheel balancing and alignment first. and those are usually the cheap fixes too... the fact your wheel is getting eaten on the inside first sounds like alignment especially, tho.

1 tire balance
2 tire balance
3 tire balance
4 tire balance
5 cheap untrue wheels
6 severe tow in

I would have another shop ballance the tires. It could be non hub centric wheels too. See if the shop can ballance with the lug pattern and not the hub. It may be ballanced to zero at the hub and you need it ballanced zero at the lugs. If it is only shaking at 55mph, I think it's still the ballance. even though you may still have an alignment issue.

I thought this means you have excess toe out or neg camber. Excess toe in or pos camber wear the outside. You sure you have that right Dr?

As far as wheel shaking I vote bent rim or tire balance.

Tire balance rear tire. 55 MPH is typical for noticing a rear wheel out of balance. 30-35 mph is usually front.

balance them wheels if not fixed with standerd balence then get the fronts balanced on the car early cars oft need to be balaneced on the car cuase they are not hub cnetric, later cars not so bad.
you also need to get it alinged if in doubt. try balance on the car if all else fails!!!!!!!!!!!!!!!!!!!

My understanding is that shimmy at speed is almost always a tire balance issue, not alignment (unless maybe your alignment is not even in the ballpark).

I'm taking this all in. Lots of good points. Keep going and thanks

OK I got this one!!

I was haveing this problem and I tried everything until I got frusterated and just put two new tires on the front! Wow problem solved, it turned out that the car had been sitting so long on the ground that the tires had a flat spot on them!

Jack stands are your friend when you are storing a car for long periods of time!

with everyone.

What period of time constitutes a long period of time?

If I know my car is going to sit for longer then three weeks, I put it on jackstands. IE, as soon as I put it away for the winter, it goes on Jackstands unless I need it to roll for some reason. Flatspots can usually be "driven out" after a few miles on the road, unless they have sat for a LONG time.

But flat spots would not cause you to wear on the inside. Sounds to me like it is improperly aligned with poorly balanced tires - like everyone else has said.

BUT! For giggles, go and check your lug bolts and make sure they are not coming loose on one wheel.

Zach

Wear on the inside edges == toe-out. Probably combined with negative camber. Toe-out is EVIL and should be AVOIDED unless you put just a tiny amount on the front of your autoXer to help initial turn-in. And you know that you can never take your attention off of driving, even for an instant.

Shimmy can be a lot of things, from bushings to bearings to a bent wheel to a tire de-laminating to wheel/tire balance problems...

Fix the alignment. Since the shimmy got better (but not cured) when you swapped wheels front-to-rear, chances are very high that the rear wheels or tires are to blame for it. Have their balance double-checked, then inspect the wheels carefully. If that doesn't fix/show the problem, replace the rear tires.

--DD

I had the same problem (shake over 55) I re-checked everything. You know what is was? Loss of air from sitting. 205-55-15 did not notice the loss of air (tire profile i guess). Went from 25lbs to 32 or so back on the freeway. Shake gone at any speed. It took me months to figure this out.

Umm, I'm surprised nobody has brought this up. I've had shimmy problems before and it was because I didn't properly torque the lug bolts. Since they're lug centric wheels you have to be really careful to make sure the wheels and bolts get seated together properly or else the wheel will run off center.
The way I do it is torque them to 50 ft/lbs, then I knock the tire with a sledge hammer (Don't hit the rim) around the circumference. Then I torque them to 100 ft/lbs, and do the same thing before going to final torque.
Hope that helps some... BTW, the tires wearing on the inside sounds like toe out to me. If the steering is really twitchy then that's probably the problem there. But it sounds like you've got two separate problems. Anyways, good luck.
Mark D.

Again thanks. When I get to the bottom of this I will let everyone know.

You are getting good advice. You need to take a step by step approach and make sure the whole front end is right and tight.

Get the alignment done at a shop that knows Porsches, and go from there. Those guys look at front suspensions all day and should be able to find the problem.

FWIW the best way to get your tires/wheels balanced is on the car. There aren't many places left that will or can do it, if you've never seen it done before it's pretty impressive how smooth it can be balanced.

I'm guessing bad alignment and bad balancing.