993 Steering vibration

[tigerbillsbikes]

I recently purchased a 1995 993 convertible with about 82,000 miles on the odo.
The car drives great except there is an intermitant vibration or shimmy in the steering wheel at times. The tires were old (15 years old but with great tread) so I replaced them with a set of Michelin Pilot Sports to match the rears. They are 2011 vintage but have about 2000 miles on them. The pulsation and steering shimmy occurs some times while accelerating at about 45 to 50 mph. The steering id more pronounced braking in corbers at about 40 to 50 mph. I can forcefully apply the brakes in a straight line from 65 mph with not pulsation or shimmy. This car was never driven much. Of course not too good. I don't think it is a tire balance issue but .... I don't think it is warped rotors because it stops true with no pulling or vibration. I almost think the problem is tie rods or control arm bushings. I am looking for advice. Thanks!!!

[Paperboy]

A 2011 tire is 8 years old. I think tire manufacturers consider a 5 year old tire as "old".
(Recentlty changed old tires w rel low milage to new ones, Pirellis. W/O any orther change could tell improvement.)

[wesleyc]

I had the same problem with my 95 993 and I replaced the tie rods. Still shimmied until I replaced the control arm bushings. That cured the problem. I installed Cris Walrod bushings. Fd Motorsports has them and a tutorial for diy folks. There are other bushings out there too.

[Nine9six]

Originally Posted by wesleyc

I had the same problem with my 95 993 and I replaced the tie rods. Still shimmied until I replaced the control arm bushings. That cured the problem. I installed Cris Walrod bushings. Fd Motorsports has them and a tutorial for diy folks. There are other bushings out there too.

^^^ This, plus an alignment and corner balance from a qualified Porsche specialized alignment shop.

[AOW162435]

Due to age & mileage, I'd vote for control arm bushings as well.




Andreas

[tigerbillsbikes]

Thanks for all the input. The tie rod ends look good and are tight. The control arm bushings do have some very minor cracks but are quite sound. Since the pulsation appears mostly during braking I have decided to order rotors, pads, dampers, hoses etc and will go through the brake system. I believe this may take care of this somewhat very minor issue I am experiencing. The car drives great otherwise. More to follow. I'll let everyone know how this turns out.

[Porsche 964]

Recently my 95 C2 exhibited similar steering intermittent vibration when driving between 45-50 on the freeway. It turned out the tire pressure in all 4 tires were off balanced as I have not been checking the tires/driving the car for about 6+ months. The proper cold tire pressure is shown on the driver side door sticker. Take a reading of your tires, make any adjustment to the pressure and see if that makes any differences.