lambotex

OK any suggestions would be appreciated. I have a shimmy at 55 to 60 MPH in my 1996 Turbo with 42k miles. The car has PSS9's with 10k miles on them and 996 Turbo wheels everything else is stock. I have tried several things and searched the site for ideas but my tech and I are at a loss. The shimmy was there when I bought the car and I have been throwing parts but no luck. Here is the list of what we have tried...

Tie Rods/ Replaced
Ball Joints/ Replaced
Front Bushings/ replaced
Alignment
New Wheels
New Tires/ Michelin
Adjust Ride Height
Balance Wheels
Run Car on Lift and Look For Issues/ Nothing
Checked Steering Rack for Leaks/ None


Any ideas out there?

Foxman

That's a pretty thorough wash list. Where precisely is the shimmy, and at what speed(s)? This may be drive train related...

NP993

which front bushings were replaced? a-arm?

NC TRACKRAT

Checked wheel bearings/hubs? Checked rotor run-out with a dial indicator? At the speed where shimmy is experienced, depress the clutch. Any difference?

deekay911

I know you said you have done the front bushings, but that's exactly the problem I had before I replaced the lower wishbone bushes with Walrods. Problem then solved.

What bushes did you replace with?

lambotex

I replaced the front bushings with FVD sport RS type rubber. The shimmy is a slow back and forth in the steering wheel at 55 to 60 MPH.

phoneyman

Have you measured the ride height before/after the adjustment to ensure its not too low? Seems to me you tackled most of the other common culprits.

Were alignment numbers in spec?

lambotex

Car is about RS height, not crazy low and alignment numbers were fine.

Coop

Tire pressures even?

lambotex

yes

pp000830

Have someone walk behind the car as you roll across a parking lot and have them sight along the line of the tire faces. See if they see any wobble at the wheel as in a bent hub this can cause wobble that is experienced as a shimmy at higher speeds. Also if the tire/wheels are properly balanced and for some reason flat fix fluid was introduced introduced into the tire it can cause an out of balance or simply not fully seated. It is conceivable that a rotor can be out of balance or not fully seated. A shimmy in the steering wheel is the front a shimmy you feel in your butt is the rear suspension. Last but not least uneven tire ware as the result of the shimmy in and of itself can cause the issue. As in you fixed the issue but now the tires are no longer round. I would get the tires inspected for uneven block wear.

996scott

it sounds like the control arm bushing to me. Mine did that exact same thing at that exact same speed. Did the bushings from FD Motorsports and it's perfect now. Sorry I'm not of much use other than that. good luck.

lambotex

I have replaced the control arm bushings less than 1k miles ago and the shimmy did not change.

race911

I'll shoot for Red Turbo Syndrome. Cousin's car had similar when he got it. Frustrated the hell out of him (and the previous owner--kinda how he walked into a $40K deal). It was one of the REAR suspension links that was oh-so slightly bent. If forget which one, but I can ask him.

Yeah, made no sense to him, me, or half a dozen other experts consulted..........

OverBoosted28

^^^^^^ this was something I was also gonna mention. You can have a slight problem in the rear somewhere that'll feel like it's originating from the front.