DarrenD

On my 1984 Porsche 944 I have a front end shimmy. EASY you say, balance the wheels? Done that, 3 times. It's the tires then? Tried 3 sets, on 3 different wheels. Tie rods? Nope, no issue there. Ball joints? Nope, all good. Rotors? OEM in great shape. Wheel bearings? Maybe, not sue how to verify any better than the washer check. Alignment? Had it set up twice by the best guy in the area. New upper strut mounts you say...? Check!

Wheels were checked and are true. Tires are good. All new bushings and parts in the front end. WTF? Why does this thing shimmy??
The front struts have been replaced with inserts. I personally don't like how they fit but apparently that is how they are installed. Couold it be the fact that there is a tiny bit of play between the body of the strut and the insert?

What am I missing? I'd like to buy some coilovers, but I'm not doing it until I can get the shimmy sorted out, Anybody been through this hell?

plumbum

I have a similar condition. Shimmy around 117km/h. I balanced the tires and most of it went away but it is still there. Like you my front end is tight.

I got use to it and as it only occures at one speed it does not bother me a lot. I would call it mild.

How bad is yours? Does it come in at different speeds? Wondering if a brake rotor out of balance would cause your issue?

Is it in the front end only (steering wheel shaking) or rear (seat shaking)

pontifex4

As plumbum says, my bet is a warped rotor.

DarrenD

Rotors don't typically warp I've been told. Pulsing in the pedal is caused by hotspots, which shouldn't cause and balancing issues. The rotor COULD be warped, I will check them on the lathe at work. The steering wheel shakes at anyhing over 100 kmh, it's bad enough to drive me nuts and not want to drive the car long distances.

LP944

I have the same issue but It fluctuates from time to time, mainly speeds over 68 mph there is a bit of a wiggle until about 75.

DarrenD

Seems to be very common, do most people just live with it?

Perculator00

How exactly does the "shimmy" feel? Is it just a straight vibration felt through the steering wheel?
Sorry not to Hijack your thread or anything, just never have known much about wheel shimmy. I would assume a bad wheel/tire is the main area that could cause shimmy correct..

On another note, trying to wiggle/push/move the wheel around while attached to the hub and raised is still a good test/check for bad wheel bearings? If the bearings are bad will you almost certainly feel it in addition to hearing?

LP944

I pretty much deal with it, I just recently had some rotors checked and wheels balanced, and everything up front looks straight and correct.

pontifex4

I just took a warped rotor off my front left: I had a caliper that was sticking a little, and it wouldn't release one of the pads. Even this wouldn't have been that big a problem, except that when you get the brakes hot (which I tend to do a lot) then park the car with a pad stuck against the rotor, you get a taco.

Of course, this may not be what it is in your case, but it's an idea. Do you hear any noises when you turn, or turn sharply?

TexasRider

You might check the steering itself. The steering connections and box could have something loose or worn there as all of the other components are pretty much ruled out. I have felt looseness there inother cars that felt like a shimmy.

Ater all that work I think it is worth doing the bearings too as so many problems have been found and resolved with a new bearing set. They are not too hard to do and not too expensive either. I saw one car that the hub felt tight and the bearings were broken inside. There was enough rust and crud was inside to make it feel tight. I dont think that is a problem here but it certainly worth doing.

DarrenD

I am thinking bearings too. The wheels spin very freely which is not exactly what I'm used to. Maybe they're a bit too free. Anybody have any thoughts on that, how easily do your front wheels spin?

Medski

I had a jeep TJ that did that and everything was straight. I figured it was either the power steering or unevenly worn tires... I'd look at how the power steering is doing.

TexasRider

You wont necessarily need the lathe. Just put the dial indicator up there and rotate the brakes and measure up. There will be some some high and low on the rotor face and some run out both. But it should be relatively small. Not any 0.250 or 0.500 kind of thing. And you will know that for future use. I bet it is even better once they go back on with the new bearings.

Any other rubber parts as Aaron talk about below?

ramius665

How do your castor blocks look? If the rubber is worn out then it will cause a shimmy.

James Chimney

I had to add spacers on my 85.5 944 for 16" rims, and they are not "hub centric" so if you use an impact gun I have a really bad wobble/shack if I tighten up each lug nut a little bit at a time it almost goes away completely, give it a try as the lug nuts tapper down and pull the rim to the hubs some times it pulls it off center, at least it did on my car, good luck