How to prove worn drive shafts?

Adstar · Unread post by **Adstar** » 22 Nov 2006, 14:31

I have another recent topic regarding my vibration and tyre wear problem.

I have had all 4 tyres replaced and balanced. I have had 4 wheel lazer tracking (not the hangers on the rear wheels) which adjusted both the front AND REAR tracking.

Currently the front tyres, show no wear after 500+ miles. Rear tyres are new since monday and not showing any deterioration.

The vibration is still present!

It is at around 65-75ish. I can drive through it to cruise fairly smoothly at 80+, which would hint at a rotational resonance. It is more prominant when NOT under load! If I'm accelerating I can feel it through the sterring wheel and the car "buzzes" (vibrates a little but not much). If I lift off (not braking) the vibration is increased the steering wheel is visably moving. If I brake it obviously shakes through the "zone" and smooths out quickly.

I have read about the drive shafts, specifically the inner joints, on other cars causing similar problems. However I have also read that mine are £120+ a piece! Given that I have brought a clutch and 6 tyres in ther last 2 months, I am looking to PROVE the drive shaft is at fault before I spunk more money away....

How can I tell that the joints are gone? Im not mechanically inept, but I don't have the time to be taking too much apart or be rolling around in muddy oilly water.

Any other ideas will also be considered if the symptoms sound simialr to another problem.

thanks

Adam.

AndersDK · Unread post by **AndersDK** » 22 Nov 2006, 14:53

Usually an empty parking lot is used to test driveshafts :

Drive slowly in circles with steering wheel at full lock either way. Any worn or defective driveshaft will clearly feel like a roughness from the corner its located. The car will shake sidewards and in the driving direction, as the shift in CV or inner joint friction also shifts the load on the engine.

It does in fact feels like one of the driving wheels suddenly have become more or less oval.
Once you have tried it, you NEVER forget how it feels.

You have focused a lot on the tyres, and I believe you can rule out a tyre fault now.
There is one single component in particular that can cause the symptom as you describes it : a defective shock absorber which can cause the complete suspension to catch resonance at certain speeds.
The only diagnose is a replacing.
If you have a clear feeling which side's wheel is causing the problem - then you could try swap the shockers side to side. If the problem moves - its the shocker.

Also an ever so slightly out of true brakedisc can do this.
Be sure the hub surface is clean and even - and likewise the mating surface on the disc.
Again : a side to side swap will immediately move the problem if caused by the brakedisc.

Unread post by **504** » 22 Nov 2006, 23:35

just a thought, your steering rack isnt loose is it?

Adstar · Unread post by **Adstar** » 23 Nov 2006, 09:06

Thanks for the replies so far. I will try to have a look at the weekend. Finding an empty car park could be interesting! But I will be check the steering rack fairly quickly I would think. Hopefully I wil be able to rule out a few more causes to this infuriating problem.

It used to be such a nice car for cruising through the country. So easy and smooth!

Adstar · Unread post by **Adstar** » 11 Dec 2006, 13:19

Its taken a while to find the time and place to drive round in circles! But I managed it.. and my wheels all seem round! What I mean to say is that there was no knocking or vibration when on full lock, in either direction.

I noticed a little movement when just off lock, but I wasn't in a position to perform and larger circles.

Any further ideas would be welcomed. I will be bokking the car in to my mechanic in Jaunuary, and I would prefer to give him at least some hints rather than spending money for his time to find it from scratch!

Thanks

Adam.