Propshaft 'clunk'.

M3 Compact · #1 29th January 2015, 05:22 PM

<40K miles 2009 3.0 Tdi AUTO has a 'clunk' when changing F/R direction and taking up the drive. Also very occasionally when changing gear.

We've had it on the ramp; it's easy to replicate the noise by gently taking up the drive with the footbrake applied and I think my initial suspicions are incorrect.

It sounds from inside to be coming from around the centre of the car and I was expecting to find a failing propshaft centre bearing, but despite being able to 'feel the noise' while holding the centre bearing housing, there is visible rotational movement in the propshaft rear joint where it connects to the diff pinion flange.
It's as if there's some 'slack' in the rear joint/coupling.

Google hasn't been much help. So:

Is this a common issue with Quattro propshafts?
Audi only sells the complete shaft at £1100, does anybody know where I could buy just the joint?
Is the joint/coupling likely to be used in other models? (Wifey has a B7 A4 3.2 Quattro MANUAL vert and I could try swapping the joint over.)
Any links or alternative resources that might be helpful?
Or any thoughts/suggestions at all?

Thanks in advance.

jza8 · #2 29th January 2015, 07:45 PM

Are you sure it's not one of the engine, gearbox mounts?

Delboy · #3 30th January 2015, 01:53 AM

The rotation of the rear coupling will be the back lash in the diff along with any slack in the drive shafts etc connecting to the wheels. The majority of the slack will probably be from the diff

M3 Compact · #4 30th January 2015, 02:02 PM

Thanks for the replies.

We've built a few rally car diffs and it doesn't look like back lash in the diff or shafts.
There seems to be a 'two stage' rotation, with the first step taking up the slight 'slack' and then when more torque is applied there's a significant second rotation that leads up to the clunk. It's as if there's some type of 'cush drive' inside the diff, which seems extremely unlikely.

When on the level I can change F/R direction and creep the car on tickover without causing the clunk, but as soon as any further torque is applied it takes up the movement and clunks.

No we aren't 100% sure that it isn't a mounting and that's what I'd expected to find (propshaft centre bearing carrier was prime suspect), but the visible rotation in the rear coupling/joint really does point the finger.

If I can't find any specific info I'll take the coupling off and investigate it, I was hoping to line up a replacement source or firm up a plan to use the one off the A4 beforehand tho.

Any in depth technical info available for Audi transmissions?
I don't mind buying some if it's available commercially at a sensible price, as we're also considering an S3/A3 Quattro rally car.

snapdragon · #5 30th January 2015, 02:14 PM

I haven't hears of this before on any forum, but when you are googling, don't forget to try searching the same symptoms with VW Phaeton and Bentley Continental.

David's8 · #6 30th January 2015, 03:07 PM

Can only suggest you look at all the tech info in the "Tech Dump" sticky for D3s.

http://forum.a8parts.co.uk/showthread.php?t=9347

M3 Compact · #7 30th January 2015, 06:01 PM

Quote:

Originally Posted by David's8

Can only suggest you look at all the tech info in the "Tech Dump" sticky for D3s.

http://forum.a8parts.co.uk/showthread.php?t=9347

Great info, thanks for the link.

Quote:

Originally Posted by snapdragon

I haven't hears of this before on any forum....

Which is in line with my findings, or lack of, and makes me further inclined to feel that our initial diagnosis seems unlikely.

Quote:

Originally Posted by snapdragon

....
when you are googling, don't forget to try searching the same symptoms with VW Phaeton and Bentley Continental.

I've given up Googling now TBH; I've been searching for all Quattro models assuming that they'd probably use a similar style of rear coupling.