Torque Tube vibration dampener clunk
 

I am the exited new owner (for the past few months) of a '87 S4 auto RHD. Still working through a few niggles on an otherwise super fun car.
There is a clunk coming from the transmission, which I have diagnosed from reading the forum to be the TT vibration dampener / balancer sliding up and down - if I accelerate fast'ish from standstill it clunks, when I brake hard enough it clunks - if I have not braked hard enough, the clunk is not there on pull away again (idea is that it is still at the back), and so on.

Question: Is this harmless or does it need attention?

This is a common problem with ageing. The damper is designed to reduce noise in the cabin and is a static item that the drive shaft spins inside [no contact]. The auto tube has two shaft bearings and if my understanding is correct, the damper lies within these two bearings. The damper and the shaft bearings are held in place by rubber sleeves and with age they go hard and loose the ability to hold things in place. If the damper is loose chances are the rubber of the shaft bearings is no better and as the damper slams about there is a good chance it will displace the shaft bearing holder and if the bearing holder is out of position then vibrations and shaft flexure will doubtless start to happen and more serious issues will eventually emerge.

My take is that if the damper starts sliding around then it is time to remove the torque tube and replace the bearings with Constantine's super bearing kit- if I remember he recommends fitting three bearings and discarding the damper. You can read more on his website http://blackseard.com

Forgot to mention- for the 1987 models some had the 25mm drive shaft and some the 28mm drive shaft- if you were to place an order for these bearings you need to know which one is fitted.

You should also note that the 28mm drive shaft is thought to be problematical as some fail at the base of the splines. I have a theory that this happens when the flex plate clamp slips - you should be well aware of this potential issue as well. If you were to go for the super bearings you would do well to also fit Constantine's super clamp and have done with it.

if your working on the TT then you can also buy one of Greg Browns new driveshafts,
yes its all expensive parts but they will never fail

Thanks for this. Oh well, another thing to add to the To Do list