tshih

My wife's 1996 993 tiptronic has developed a severe vibraton at speeds over 40 mph. The car was running fine over 2 days of DE at Poconos in PA. The car has 48000 miles the first 45000 it was running 18" aftermarket wheels and tires. It now rides on OEM 17" Cups with Kumhos (3000 miles).

The steering wheel does not wander on a straight and flat roadway. The vibration is like a pitching and bobbing side to side kind of vibration (or shaking). I removed the front pan cover and looked carefully at the bushing of the front control arms. The passenger side has a tear in the rubber bushing (see photo posted). Is this wear the cause of the vibration? Does anyone make new replacement bushes or is the correct fix just to replace the entire expensive arm?

TheOtherEric

Your pic didn't show up. If you need some help resizing and posting it, shoot me an email and I'll help. (click on my username, etc.)

I replaced my front control arm bushings with urethane bushings. So yes, it can be done.

TroyN

Eric, what brand of bushings did you use? Do they have zerk (sp?) fittings to be able to lube them? How do you feel about their performance?

tshih

Eric,
would like to know where to get the bushings you used and are they too noisy for street use? How does it affect ride. Although at this point the car is shaking so badly anything would be an improvement.

kdurg

Eric...

Curious on the specifics with your urethane bushings as well. Been battling the wheel shimmy since ownership. Haven't been able to truly dial it out......

What prompted you to switch them ...did you have problems prior to ?

TheOtherEric

To answer some questions, I got my urethane bushings from Powerflex after hearing about them on R'list:
http://www.powerflex.co.uk/index.asp

I think I purchased thru Bimmerworld. I didn't have any particular reason why I got them; I just thought it might be a nice upgrade to tighten things up front. The factory parts are pretty soft rubber. I haven't noticed any particular difference (good or bad) after installing them last winter (about 3000 miles ago?). You don't lube them, and only time will tell if they hold up. But so far so good.

TheOtherEric

Here's tshih's pic that he emailed me.

tshih

Thanks Eric,
I went to the Bimmerparts.com site and didn't see the bushings you mentioned in their online catalog. Do you email them with a request for polyurethane bushings by powerflex and they quoted you price and availability? How were the bushings installed (with a press after the old rubber ones were pushed out?).

tshih

Eric,
Just looked closer at the powerflex link and their USA distributor is actually Bimmerworld.com.
I ordered a set for $190 enough for all front bush replacement. Thanks for the link and info.
Tom

tshih

just to follow up after seeing my new tech. The problem of the vibration was not related to any suspension component. It turned out to be a simple matter of a bad rear tire whose steel belt was deformed and starting to stick out of the center of the thread area. That explained why the vibration started suddenly. I had focused my entire attention to the front wheels and tires since they were related to steering and the vibration was felt through the steering wheel although the car doidn't wander. So after changing the tire, the car rides perfectly smooth again. However it doesn't help you since I don't have first hand experience changing the control arm bushings which still haven't arrived yet. So sorry to those waiting to find out how hard they are to change.

tj90

So how hard are they to change? What is required to change out the bushings?

FLYT993

I'm curious about this as well, since mine are "torn" and I've heard from one of the most reputable 993 guys in SoCal to change the entire arm out....but DAMN!! at $1800 (parts/labor) it provides some incentive to look for suitable alternatives.

Steve Weiner-Rennsport Systems

Having had plenty of long-term experience with urethane bushings from several manufacturers (not Powerflex), I would never install such things anymore without providing a method to re-lubricate them from time to time.

This involves putting some grease channels into the bushing, drilling some holes, and installing zerk fittings to each one. After that, these work pretty well when lubricated with the corrrect grease,...

JasonAndreas

You can find instructions for checking and installing the bushings in THIS THREAD.

tls

For what it's worth, I took in my 97 C4S to a highly respectable shop in So. Cal as well that recommended I change out both arms since bushings couldn't be replaced. After driving about 100 miles, I had found that the arms were not the problem. Needless to say, the car's back in the shop today, and I'm out $2200.