Thunk/clunk sound when decelerating/accelerating

[ats101]

Hey man,

I have gone over all the manuals on Newtis. Not sure what might be causing the clunking noise but I'd be curious to see whether the prop shaft has completely mated onto the spleens of of the diff input.

Did you find out what the problem was?

[Pajarito61906]

Originally Posted by ats101

Hey man,

I have gone over all the manuals on Newtis. Not sure what might be causing the clunking noise but I'd be curious to see whether the prop shaft has completely mated onto the spleens of of the diff input.

Did you find out what the problem was?

Look at my previous thread this could be a cause

Differential Clunk Potential Cause https://f80.bimmerpost.com/forums/sh....php?t=1716408

[Tom978560]

Originally Posted by Pajarito61906

Look at my previous thread this could be a cause

Differential Clunk Potential Cause https://f80.bimmerpost.com/forums/sh....php?t=1716408

Just put new diff bushings in my car, reinstalled everything according to bmw factory procedure and still have multiple clunks, almost as if the driveshaft has a bad u joint but there obviously are no typical you joints, only a cv joint and a guibo. Going back under today to check torque on the subframe bolts, inspect new poly diff bushings and inspect driveshaft for play.

[ats101]

I haven't got this problem of clunking but I will be dropping the rear subframe and going for the ECS bushes with the dual mount diff rear bracket. People have reported that clunking has occurred following this modification.

It's a bad feeling when you have done all that work and the outcome is suboptimal.


If anyone has done this DIY - I presume the prop shaft sunk nut locks into the bihexagonal diff nut therefore when you tighten it back onto the prop shaft, it pulls and locks the prop shaft onto diff input?

Also, what size spanner is required to undo the sunk nut?

[Tom978560]

Originally Posted by ats101

I haven't got this problem of clunking but I will be dropping the rear subframe and going for the ECS bushes with the dual mount diff rear bracket. People have reported that clunking has occurred following this modification.

It's a bad feeling when you have done all that work and the outcome is suboptimal.


If anyone has done this DIY - I presume the prop shaft sunk nut locks into the bihexagonal diff nut therefore when you tighten it back onto the prop shaft, it pulls and locks the prop shaft onto diff input?

Also, what size spanner is required to undo the sunk nut?

I just did it. Pm me for more info and/or pictures but i will be posting a youtube video soon. I also noticed the same amount of clunking before and after and barely any increased noise but it definitely drives better. I also did the ecs bushings. And you are correct. When you undo the sunk nut it backs off of the prop shaft so you are turning it clockwise when removing and counter clockwise when installing. There are tabs on the sunk nut that grab the inside of the 12 pt nut. Its pretty tough to undo but i used a long ½” ratchet with a 1 ⅞” crowsfoot grounded down to fit the nut exactly. The sunk nut measures around 50 mm but finding the right crowsfoot was hard so i made one. Undo that first and remove it off of the diff before undoing the guibo. It makes the driveshft come out way easier.