GRUWEZ

Recently my 1997 993 Turbo has developed a rattling noise whenever I turn the steering wheel clockwise. The noise occurs at the final 1/2 turn of the steering wheel, before it reaches the full stop. It seems to be stronger when the brakes are applied as I turn the steering wheel. When sitting in the driver's seat, the noise appears to come from somewhere close to the left front wheel well.

My first suspicions go towards the steering rack. However, my technical knowledge of these beasts are pretty limited.

1. How can I check what exactly is at fault? Put the car on jack stands and have an assistant turn the steering wheel while I listen up close?
2. If it is not the steering rack, what else could cause this noise?

Thanks for the feedback.
Rik Gruwez
Bruges, Belgium

MarkD

Do you hear it only when rolling?
is it a sort of clicking noise?

Sounds like the outer CV joint on one or both front axles.

GRUWEZ

Well, I definitely hear it with the car standing still. Haven't really heard it when it is rolling, but there are probably too many other noises. Anyway, I will heed your suggestion and check out the CV joints as well. Thanks!

malcolmd

MarkD is suggesting that if it is there when rolling but not when standing, it could be the CV joints. Now, as you stated that it is there when stationary, it won't be the CV joints.

GRUWEZ

OK, thanks for that. Steering rack would be the most likely culprit then?

911/Q45

I'd vote for upper strut mounts or lower control arms. I had a clunk that I could feel in the steering, so I replaced the lower control arms to no effect. When I replaced the upper rubber mounts it went away. The upper mounts are much cheaper, so do those first. I couldn't tell by looking that they were bad, but could hear the clunk with my head in the wheel well.

MarkD

OK, so you can make the noise happen standing still. As Malcolm said, that rules out CV joints.

Could be rack, could be supsension as Q45 suggested...
IMHO, it will be hard to diagnose here. Maybe get someone to turn the wheel for you while you track down the source of the noise? Good luck and let us know what you find!

GRUWEZ

It is not really a clunk but more a ratchet kind of noise.

Did some tests yesterday. I had the car on jack stands and removed the front wheels. My beloved wife turned the steering wheel while I had my head inside the wheel well. No strange noises. It is only with the wheels on the ground that the noise occurs. The search goes on...

Regards,
Rik

911/Q45

Unloading the suspension by jacking it and removing the wheels doesn't tell you much, try it again with the car on the ground.

GRUWEZ

I did, but then the car sits so low I cannot really crawl underneath. But the noise is still there. Ideally I would need to drive it up a ramp hoist. Perhaps best to drop it off at the dealership...

MarkD

I think we are heading for what Q45 suggested, suspension related.
Though it is still possbile the rack only makes noise under load.

You said it is only the farthest ends of steering travel so probably suspension when under a load.
Do you get any vibrations in the steering at any speeds?

GRUWEZ

Actually, yes. I thought that this was due to my nearly worn tires, but perhaps there is more going on there. What am I looking at? Worn suspension bushings?

MarkD

Does it start vibrating at about 45-50mph and go away around 60mph? (sorry, didn't covnert to KPH)
If yes, control arm bushings are the likely culprit. Chris Walrod (here on RL) has a great replacement uerthane bushing.

Otherwise, could be ball joint or tie rod. Given the noise you are hearing at the end of steering travel, I'd suspect ball joint... though I can't say I've ever heard that noise caused by a ball joint on one of these cars.

Are the strut tower nuts tight (top side)?
Are the lower strut bolts tight?

GRUWEZ

We are onto something, I think. Yes, this is exactly what it does. Vibration starts at around 45-50 mph (say, 70-80 kph) and goes away around 60 mph (approx. 100 kph). How hard is it for a backyard mechanic to replace the bushings? As far as I can remember, if you take the car to a Porsche dealership, they will change the control arm only as a complete unit. Therefore, I would like to do the job myself. Any special tools I need?


Haven't got a clue. I just drive the car.

Thanks a lot for leading me in the right direction. Now I only need to find out if I can do it myself.

Regards,
Rik

911/Q45

If you change the control arm as a unit, it's easy to do yourself. The factory bushings are kind of complex and I wouldn't recommend swapping for urethane.