Urs4 drivetrain noise

[AUDIDAVES4]

I have been rebuilding my S4 over the last year and finally took it for a little spin along the road last night, pulled away from the house in 1st then into 2nd no problem, I shifted into 3rd and put the foot down and there was a knock then a scraping/ grinding noise from the centre/rear of the car, I stopped reveresed and headed back to the house the noise had stopped, I repeated the drive and the same happened again, next time after that I drove without hard acceleration and there was no issue.
Any ideas?? Could it be the prop bearing?
any advice would be much appreciated.
Thanks

[Thecrispynoodle]

If it sounds like it’s being caused by something rotating rubbing something else then it’s likely loose or bent heatshield hitting the centre driveshaft. Hopefully nothing worse. More torque in 3rd so more movement so more contact.

[Thecrispynoodle]

If it sounds like it’s being caused by something rotating rubbing something else then it’s likely loose or bent heatshield hitting the centre driveshaft. Hopefully nothing worse. More torque in 3rd so more movement so more contact.

Also you will be able to see the shiny scoring on the centre driveshaft from where it’s coming from if so.

[AUDIDAVES4]

Removed the prop shaft this evening and the rubber round the bearing fell apart, however there doesn’t appear to be any scoring on the shaft but the bearing needs replaced regardless.

[Thecrispynoodle]

Removed the prop shaft this evening and the rubber round the bearing fell apart, however there doesn’t appear to be any scoring on the shaft but the bearing needs replaced regardless.

Oh dear. Time to overhaul the whole thing then :-) Mine has some play but it’s still intact.

[rynaqui]

Good to change all the outer and center joints as well whilst there. Did that in my car some time ago and made a great difference

[AUDIDAVES4]

Where’s best to get the rest of the joints? Price??

[Thecrispynoodle]

Where’s best to get the rest of the joints? Price??

Find driveshaft specialists near you as the centre joint will need to be unstaked and rebalanced, All new CV joints, bolts and support bearing gonna cost you £200-300 in parts plus whatever labour is involved.

[vag_noob]

If the CV boots are not torn then there is probably no need to replace the driveshaft CV’s or boots. But you probably want to repack the CV’s with new grease. The u-joint is not necessarily bad either. If you replace any of these you will need the shaft balanced.

If it is just the center bearing then it is an easy fix.

[AUDIDAVES4]

Everything else appears to be ok so it’s just the center bearing, I do the work myself so no labour cost either. I have the new bearing so should get it built back up this week.

[Thecrispynoodle]

Everything else appears to be ok so it’s just the center bearing, I do the work myself so no labour cost either. I have the new bearing so should get it built back up this week.

Where did you get your centre bearing from?

[AUDIDAVES4]

On eBay, it seems to be decent.

[AUDIDAVES4]

Car built back up and road tested this evening, no knocking sounds but there seems to be a whine from the rear diff

[Thecrispynoodle]

On eBay, it seems to be decent.

I’ve seen those but have a larger external support diameter presumably that wasn’t an issue?

[AUDIDAVES4]

It has the same dimensions as the one that came off