Hoping you can help, the mechanic I trust can't figure out the problem. I have a 2002 996 turbo tip with 60km.


Problem: turning left while accelerating I feel a vibration, when I turn left with out accelerating there is no vibration. Turning right has no problems


What they have checked: end links, drive shaft, suspension for anything loose.


help!

 

Also consider checking both wheel bearing and cv joint play which could vibrate under load.

Can you feel the vibration in the steering wheel ?

 

+1 on a bad wheel bearing as a possibility. clue would be noise/vibration while turning, and none when not.

 

Does your car have lsd?

 

thanks for the feedback!


-no vibration on the steering wheel
-no LSD


will suggest wheel bearing to my shop


thanks

 

Kind of odd to have to suggest wheel bearing to a shop given the symptoms.

 

I personally have never had a wheel bearing cause a vibration. It's always been a noise. Like grinding or howling. It's speed related and gets quieter when turning. For example. If the noise is present during left turns and gets quieter or goes away all together when turning right, I'd suspect left front wheel bearing. Not ALWAYS true but close.

~id check if wheels are tight or maybe its the tire.

 

thanks, Mechanics kind of said the same thing...he told me he didn't want to throw parts on for no reason but wait till it gets worse.

 

Have you checked the obvious...tire wear, inflation pressure, does it happen on all road surfaces?

 

yes to all and only when accelerating while turning left on all road surfaces...drove it today again and it looks like when I make a sharper left turn.

 

Cv joints probably inner

 

To check your CV joints, get your car up off the ground. Clamp vice grips on the axel with a rag under it so as not to scratch it. Have someone put on the brakes, see how much the axel will rotate back and forth. My old 996 c2 with 140K on it had lots of play. The tip if the vg handle would move 3/4". It developed a clunk, that's why I was checking. Bought 2 used axes off e Bay for $125 each. They had virtually no play and made the car feel much tighter.

 

Since the problem is not occurring all the time, but only in certain "conditions", you have what we statisticians call an interaction (the effect of a factor depends on what other factors are doing). To truly study interaction effects you need factorial studies...very challenging for the individual car owner where they have limited ability to test and measurement systems are lacking (like I think its a vibration...). So we play the "game" of trial and error to get the symptoms to go away...and unfortunately when it does, we conclude, often erroneously, it was the last thing we did. My guess is it is a combination of things that culminate in your vibration effect. None of them may be significant in their own right.

 

Well, the OP reported the shop checked a number of other possible sources that could account for the behavior. I'd not expect the shop to throw new wheel bearings at the behavior but at least with the car in the air to check for any excessive wheel play, any excessive roughness, that could be a sign of wheel bearing problems.

I mean I find it hard to avoid when coming up to my car while it is on the lift and supported by the body lift points giving each wheel/tire the old wheel/tire a play test at the top and bottom and from side to side.

The reasons I don't do this because I don't want to make the tech think I don't trust him to do his job and I don't want to push my luck and possibly compromise my freedom of access to the service bay and techs. If the SM sees me venturing into too close proximity to even my car without being accompanied by a tech he might limit my access.

 

I had this problem at the track, but it was right turns and left rear vibrating. At one point felt like a flat tire it was so bad. My mechanic says the axles were failing. Pricey to replace, but 14 year old axles on my mostly track car needed some attention.