Rear-end Clunk when shifting

[Cscat]

Hello all, I have a question about a noise I'm hearing. I tried to search for this, but nothing seems to turn up. If there is information on it that I missed, please post a link or tell me what/where to search for it. Thank you.

I have a 6-speed 2015 M3, bone stock and 40k miles. When shifting "spiritedly" there is a clunk from the rear end. Enough to where any passengers will ask "what is that?". The car drives fine, shifts normal, no issues that I can discover. But there is a loud clunk from the rear of the car on high-rpm shifts. If this is normal, I am fine with it. Just wanted to make sure before I start digging into the car or leave it be. Thanks in advance.

[M3king2019]

My M3 makes a loud clunk/bang noise too when I apply the accelerator, it's like there is something loose in the rear of the car, I had an M4 before and it never made this noise, it's booked in to be looked.

[M4_CaptFlashheart]

Its normal. All three of my M4's in the last 3 years have done the same. If in Sport+ it seems to be worse. I even took the main BMW tech out and he said most, if not all do it. The fact that I brought it to their attention gave me reassurance as they said if I was to have any issues with it, they had been made aware. I've never found it to get worse and had no issues with any of the 3 M4's i've had so far. (oh, and one of them seemed to be worse than the others but again, was told all normal.)

[M-Pilot]

It's not normal. My M4 Comp used to do that especially in Sport+ throttle in which the throttle input is much more sensitive. Either during agressive shifting or when I tap to the gas pedal suddenly at or above 3-4K RPM. I would hear a loud clunk from the rear off the car. I took it in and the dealer inspected it. They found out that the diff bushing was cracked so they replaced it under warranty. I had less than 15K miles when this happened but I tracked mine quite a few times. I'd say get your diff checked out.

[M3king2019]

So my M3 was in the dealers today to diagnose the clunk noise, called me to say they couldn't find anything wrong, I said to look at the diff bushing, turned out to be cracked also!!
It's a big job he said, 1 and half days, will be done under warranty, car only had 7k miles 2018

[papasmurf_m3]

Originally Posted by M3king2019

So my M3 was in the dealers today to diagnose the clunk noise, called me to say they couldn't find anything wrong, I said to look at the diff bushing, turned out to be cracked also!!
It's a big job he said, 1 and half days, will be done under warranty, car only had 7k miles 2018

Let us know if it still persists. Now that I remember, I heard the rear end clunk on a new e46 M3 Smg back in the days on fastest shift settings. It was always noticeable. Maybe it is normal because of how the rear subframe is mounted directly to the chassis without bushings?

[M4_CaptFlashheart]

Originally Posted by AlphaPro_F80

Let us know if it still persists. Now that I remember, I heard the rear ended clunk on my brand new e46 M3 Smg back in the days on fastest shift settings. It was always noticeable. Maybe it is normal because of how the rear subframe is mounted directly to the chassis without bushings?

Thats what I was told. The clunk is just being amplified due to the direct chassis mount. Maybe the diff bush was in fact cracked????? Hmmm. I'll get them to check mine next service.

[991dc5]

My diff bushing was also cracked at 32k miles. CPO does not cover the work so I decided on the powerflex race bushing. I also replaced the front of the diff with the powerflex street bushings. The diff is a little more noisy with the new bushings but that is to be expected. The rear end feels alot tighter and removes most of the thud noise and feeling when going on and off throttle in sport and sport+.

However with the stiffer bushings, dct in S3 the shifts are really hard and can be felt alot more. Not sure if I would use S3 on the track.

[Simmadown115]

Originally Posted by 991dc5

My diff bushing was also cracked at 32k miles. CPO does not cover the work so I decided on the powerflex race bushing. I also replaced the front of the diff with the powerflex street bushings. The diff is a little more noisy with the new bushings but that is to be expected. The rear end feels alot tighter and removes most of the thud noise and feeling when going on and off throttle in sport and sport+.

However with the stiffer bushings, dct in S3 the shifts are really hard and can be felt alot more. Not sure if I would use S3 on the track.

That sucks that CPO wouldn't cover it. Since it's wearing out so quick in these cars I am surprised that even if the dealer was to fix it once under warranty, by the time it breaks again it will be out of warranty.

How much did it cost to replace them out of CPO with the powerflex?

[991dc5]

Originally Posted by Simmadown115

That sucks that CPO wouldn't cover it. Since it's wearing out so quick in these cars I am surprised that even if the dealer was to fix it once under warranty, by the time it breaks again it will be out of warranty.

How much did it cost to replace them out of CPO with the powerflex?

It's a 5-8 hour job depending on the shop you go to. My buddy owns a shop so I can't exactly tell you how much labor would cost.

The subframe and exhaust has to be dropped. The axle and driveshaft also needs to be disconnected. Remember to use new hardware since subframe bolts are meant to be used once.

[M3king2019]

Dealer replaced the cracked diff bushing on the M3 and clunking noise is still there, they said they will now have to start replacing parts until they find out what's causing it! My other M4 definitely didn't make this noise

[Beemerm3]

I'll be replacing my rear differential bushing if it's leaking with powerflex bushings.

[Andrew30azs]

Originally Posted by 991dc5

My diff bushing was also cracked at 32k miles. CPO does not cover the work so I decided on the powerflex race bushing. I also replaced the front of the diff with the powerflex street bushings. The diff is a little more noisy with the new bushings but that is to be expected. The rear end feels alot tighter and removes most of the thud noise and feeling when going on and off throttle in sport and sport+.

However with the stiffer bushings, dct in S3 the shifts are really hard and can be felt alot more. Not sure if I would use S3 on the track.

Hey man I need your advice. I change also bushings on the back on my m4 and now my transmision is more noisy. On low speeds I can hear and fell clunking noises . What do you think this is normal ?

[991dc5]

Originally Posted by Tobiasz17azs

Hey man I need your advice. I change also bushings on the back on my m4 and now my transmision is more noisy. On low speeds I can hear and fell clunking noises . What do you think this is normal ?

I do not have this issue. The diff just whines slightly louder with the bushings.

[M2C89]

Following.

[Andrew30azs]

???? Any one have same issue as I have it ? Talking about dct transmision is clunking after bushing change and is more noisy

[behindthen0thing]

I had a small squeak/ clunk when coming off power or changing forward to reverse. I looked under the car and the rear diff bushing was cracked. I had it replaced with a powerflex. The rear end feels better, there is no noise anything after replacing

[mfurse]

Is the noise something like the noise in my video here? Thunk/clunk sound when decelerating/accelerating https://f80.bimmerpost.com/forums/sh....php?t=1519762

[Andrew30azs]

Originally Posted by mfurse

Is the noise something like the noise in my video here? Thunk/clunk sound when decelerating/accelerating https://f80.bimmerpost.com/forums/sh....php?t=1519762

Hey !

Hey something like that plus i can feel like something is loose And definitely The. Lise coming from The transmission . Clunking all The time when I’m stopping my car and when I release the gas pedal at low gears . CAr sounds like shit

[mfurse]

Originally Posted by Tobiasz17azs

Hey !

Hey something like that plus i can feel like something is loose And definitely The. Lise coming from The transmission . Clunking all The time when I'm stopping my car and when I release the gas pedal at low gears . CAr sounds like shit

Get it checked, could be bushings, could be a worn synchro! Worth getting it checked out.

[Andrew30azs]

Originally Posted by mfurse

Get it checked, could be bushings, could be a worn synchro! Worth getting it checked out.

This clunk came when I went with the Powerflex purple bushings. I noticed that 2 bushings are not go all the way down to the bracket and mechanic said they supposed be like that . Worn synchro what this mean ?

[mfurse]

Originally Posted by Tobiasz17azs

This clunk came when I went with the Powerflex purple bushings. I noticed that 2 bushings are not go all the way down to the bracket and mechanic said they supposed be like that . Worn synchro what this mean ?

It's highly unlikely but I had a prematurely worn synchro in my DCT gearbox. It made a noise that I recorded in my video when going from 2>3 or dropping into neutral whilst maintaining a consistent speed. More noticeable at low speeds. I doubt it's that from what you've said!