STEERING RACK BUSHINGS?

[Mears]

'found an interesting paragraph in Jack Criswell's 993 Ultimate Owners' Guide (page 49):
'Another wear item on the steering can be the front steering bushings, found at the inner end of each tie rod. (Porsche call them 'elastic tie-rods' btw) These are designed to buffer lateral movement of the wheels and prevent this being directly fed to the steering wheel. They can soften and feel like you have a wheel out of balance.'

Can anybody please confirm exactly which part he means? Is it the rubber insert actually within the clamps holding the rack to the crossmember?

I'd quite like to eliminate this possible cause of an annoying steering vibration/harshness but don't want to precipitate rack problems, wheel re-alignment etc.

Any advice anybody please?

 

[carrerasport]

He is talking about the steering rack ball joint located at each end of the steering rack and connected to each track rod end ,normal cars have just an articulated ball joint giving a directness to the steering ,I.e you feel every bump that deflects the road wheel, Porsche thought that the modern driver might want to be insulated from the most violent bumps so fitted a rubber bush between two parts of the ball joint units, when these bushes become soft steering directness is lost and the drive becomes soft/vague from a steering perspective. they are available from porsche with or without the trackrod end assembly and are about seventy pounds each(for the joint/bush on it's own) and they are not handed (so you need two to overhaul) They typically last around 40/60 k miles and the carrera rs models dispensed with them alltogether for obvious reasons!
lemforder make them for porsche and euro car parts stock this version and this will save you around twenty pounds each and their are no down sides!

 

[Pete B]

Changing them (however careful you are to measure centre line distances or whatever) will involve re-setting the geo.
At 70K they will be perished and it allows all sorts of nasty things to happen, such as tram-lining and slight but perceptible changes to the steering wheel alignment as the rubber bush reverts to its natural shape after being compressed or stretched. If you search on that well known American site you will find a thread with illustrations on one contributer's DIY rock solid conversion.
I think it was so harsh that he got whitefinger eventually!

 

[carrerasport]

If you only change the balljoint /bush assemblys then you will not need a four wheel alignment ,but you will need to reset the front tracking (TOE IN/OUT setting) And if done carefully the tracking will be very nearly the same as before the job is started!Rarely is the toe more than 5-10 minutes from where it was before and your steering wheel algnment will also not be upset if the person doing the job is experienced.

 

[Mears]

Many thanks for your help; that makes more sense. 'sounds quite expensive for a piece of rubber but perhaps I am still not fully understanding it (and am still guessing about the USA site!). Cheers.

 

[dommorton]

All is explained here with pics:

http://www.jackals-forge.com/lotus/

 

[matthewb]

Tim

Could it possibly be a case of wheel balance? Are your wheels hollow-spoke 'Technology' or solid-spoke?

M

 

[Mears]

Thanks for the additional info. Now I can see what the issue is!
Hmmm, having had the 4-wheel tracking done just a year ago it might be better to await the next time it needs doing (accepting that it should be possible to get away with 2-wheel toe-in only to do this job). Wheels are 2-piece Targa type but yes a re-balance might be sensible first given the above. However I do suspect that the steering is 'harsher' than it should be and at 73k miles it looks from the above that the bushings should need doing anyway. The harshness is worse with cold tyres, suggesting minor flatspotting, but never goes away 100% hence my suspicion of the bushings although you could argue it either way, bushings vs balance I guess!