Steering shimmy part 2 - Help!
 

Well this is my second time to post about this problem I have with my 911. From around 55-65mph I have a very distinct steering wheel shimmy or vibration. The steering wheel shakes enough to where it shakes your arms when it is at it's peak.

Steps I have taken to try and fix this problem:

Replaced all four tires.
Balanced and re-balanced all four tires several times.
Replaced R&P.
Aligned car several times.
Checked front wheels for run-out with a dial indicator (+/- .030")
Checked for anything loose in front suspension, tie rods, wheel bearings, etc.

Still I can not get this dang shimmy to go away. I am pretty much out of ideas with out just throwing more money away on this issue.

At this point I guess my next step is to replace the tie rods with TTR's?

There is no slop anywhere that I can find. All bushings appear to be in good shape.

The problem does not go away or get worse if you turn at that speed or brake the car.

ANY IDEAS?!?



Car is a 1977 911S with 930 flares. Wheels are WORK in 18x8.5 and 18x10.5 with 245 45 18 and 315 35 18 tires. Car is lowered. Has 22/28 t-bars and carrera sways.

FisrtGen,

I had the same problem at ~65mph with my 79SC; after changing the sway bar bushings this weekend the problem has been solved.

Note, I originally thought the wheels were out of balance, but when they were checked they were spot on.

Hope this helps

Stu

Haven't tired that yet but I really don't know how that would cause that? Glad you found your problem though!

Are your tires feathered at all from a previous mis alignment. The first, or next thing in your case, I would do is borrow a set of front wheels/tires from someone in your area (with a car that does not shimmy) and bolt them on and see what happens.

Might only cost a case of beer.

Cheers

Tires look very normal...


Yeah, I just need to find someone now. I've been thinking about that for a while...

I've got same problem.... fine at lower speeds but shakes at speeds over 60 mph. Felt just like a balance issue but wheel balance checks out to within 1/2 ounce. I have readjusted bearings on both sides and checked tie rods. It's tight under there ( I guess thats why vibration comes thru steering wheel SO well).
Turns out that I've flat-spotted both front tires ( my bad!) and my 'tire guy' says that could do it. Usually you would just feel a light thumping in the steering wheel that just gets faster with speed. But apparently if the flat spots on each side get on opposite sides of each other it can set up a harmonic up and down and come back thru the steering wheel. Anyway, new tires on the way. Did you try spinning your tires with some sort of indicator against the tread to see if they're truly round? New tires shouldn't have this problem, though. I know my 30' skid on warm tires didn't do them any good.

well I just ruled that out when I had brand new tires put on and on the way home it did the same thing...

First Gen check your hubs on the back side.

I have the exact problem in my car. When I pulled the hubs off the front to upgrade my brakes I noticed a lot of buildup from 30 years of road grime and brake dust. Some places it was 1/4" thick!

I won't be able to determine if this is causing my problem until I get my engine in, but it seemes like this could be a possible cause...Hope this helps.

FSTNBLK check your PM's...

FirstGen, do you have wheel spacers, per chance? I've heard those can cause vibration issues. It's been documnted on this board.

Yeah, if you have spacers, clean the wheel adn spacers and Hub....I used light steel wool

I use to have wheel spacers but I have since removed all spacers on the car in an effort to get rid of this problem. Didn't help any...

what about play in the steering rack????

Try Mark Wilson and efhughes3. They are both Dallas area Pelicans.

I had the exact same problem with my 73.5. After checking balancing and front suspension parts, an (expensive) alignment got rid of every bit of the shimmy. Are you sure your alignment was a good one?

Ken

Already replaced the rack with another good one so no dice...

Pretty sure, at this point I'd be willing to try just about anything. It wasn't done through the dealer however.

PM's checked :)

I had to replace the u-joints in the steering column on mine to get rid of my shimmy. When I removed them they were notchy when they were articulated. The new ones were smooth. I would first borrow a set of front Fuchs with good tires to test on it. you replaced the tires but the wheels are the same. Might also put on new brake rotors. At this point it is a crap shoot and you have just about replaced everything else. Good luck with it.

Yeah, I really wish I had a set of front wheels to try so that I could narrow that as the culprit out...

Here's a trick I learned off of this board! When balancing the wheels have the weights moved as close to the center of the wheel as possible on the inside. Removed all the shimmy I had and, it didn't cost me anything!

Nikita

How much tolerance is allowable in the rotors? I put a dial indicator on the rotors and I noticed the passenger side was .008" out of flat (warped). Generally I thought this would only cause a vibration when braking however I'm looking for almost anything wrong now.

Is this worth having the rotors turned or is not the problem since I do not have any vibration under braking?

I wanted to keep this updated to help anyone in the future. I decided to pull the hubs off the car and spin them on a lathe to see if they were warped or bent or anything. Turns out they were a little distorted and I took off about 5 thousands to true them back up. I also turned the rotors while I had everything apart.

This seemed to help a ton of my problem however I also noticed that my upper strut bearings are a little loose. I think this may be my final problem.

Will update when I replace these...

To close this thread I finally fixed the last little bit of the shimmy left by having the wheels and tires "computer ride matched" at Discount Tire. Rides like glass now.

Been following this thread... Glad your all fixed-up FirstGen.

Eric

I'm gonna let my ignorance hang out here... what is computer ride matched? (Just in case flat spots aren't the only problem with my shimmy)

I didn't know they could do it either or what it was but it's the best 40 bucks I've ever spent! Basically, they check the wheel and tire seperatly for run out and balance. Then the dismount and remount the tire to mate them on the wheel in the best location in order to run the least amount of added weight. It also allows them to match a low spot on the wheel with a high spot on the tire if there is such a case with that wheel or say a light area on the wheel with a heavy area in the tire - or some combination of the two...
Sounds cool anyway. Took them about 3 hours to do it.

I'll bet my tire guys wish they had one of those! Last time I had new tires put on my Talon I made them remount one of the tires 'cause there was 1/2 lb of weights on one of them. They did place that one on the rear, but come on! They just had to spin the tire 180 degrees and all of a sudden 1 oz does it.
With regard to your out of round hub... could you feel any play in the bearing when you rocked it up/down and side/side? Or was it the hub body itself kinda bent? I hope not to have to chase it that far, but I am gonna have the wheels checked for trueness when the new tires are put on. May have to wait till next year now... stupid things are on backorder as we're all shifting into winter tire season up here now.

dentist90 - wheel bearings were tight, the hubs were not bent just abused and had been beaten on too much by the PO from things like changing wheel studs and such...

Good luck!!