[Kikerose]

Hi!

I've been reading you for a long time and I own a 2018 N55 MT6 for a few months now. The car was in a good condition (I think) when I got it, no strange noises and everything perfect.

I drove it first slowly and then I started pushing it harder, and for some weeks now I can hear a clunk from the diff everytime I release the gas or I accelerate. Is like there's loose when I accelerate, is a clunk noise coming from the diff.

I can hear it way more when I'm in 1-2nd gear, but you can hear it in almost every gear.

Should I worry about it? We checked the diff and is coming from there. But not sure if it's normal or we should open diff and check what's happening there.

We did gearbox/diff oil change with Redline DCTF and BMW diff oil. Both of them were in pretty bad condition, really really dark.

Thank you!

[F87source]

Hi,

ok I have a few questions for you:

1) Is the clunk like a metal pop can? If so It could be the rear brake shields and debris being stuck in it. There were grinding noises in my car during driving and it turns out it was the rear brake shields and rocks being stuck in it. This was resolved with a replacement of the rear brake shields with the updated parts. There is a tsb by bmw on this issue as well.

2) What is your mileage?

3) Check your diff bushings to ensure they are not damaged, and you may want to flush the fluid a second time if it was in bad shape during the first flush.

4) Scan for codes.

[Kikerose]

Originally Posted by F87source

Hi,

ok I have a few questions for you:

1) Is the clunk like a metal pop can? If so It could be the rear brake shields and debris being stuck in it. There were grinding noises in my car during driving and it turns out it was the rear brake shields and rocks being stuck in it. This was resolved with a replacement of the rear brake shields with the updated parts. There is a tsb by bmw on this issue as well.

2) What is your mileage?

3) Check your diff bushings to ensure they are not damaged, and you may want to flush the fluid a second time if it was in bad shape during the first flush.

4) Scan for codes.

Thank you for your fast reply!

Okay, going to answer you 1 by 1:

1) It's more like a clank, when you release the gas pedal it goes clank, when you press the gas pedal it goes clank. It feels like a loose. We raised the car, with 2nd gear engaged and accelerating with the wheels off the floor and the noise is coming from the diff, clearly.

2) 34.000km/21.100miles

3) My mechanic checked bushings, they are in good condition. Yes I should probably flush the oil a second time. But this noise was there before the oil flush.

4) Will do, thank you!

[F87source]

Originally Posted by Kikerose

Thank you for your fast reply!

Okay, going to answer you 1 by 1:

1) It's more like a clank, when you release the gas pedal it goes clank, when you press the gas pedal it goes clank. It feels like a loose. We raised the car, with 2nd gear engaged and accelerating with the wheels off the floor and the noise is coming from the diff, clearly.

2) 34.000km/21.100miles

3) My mechanic checked bushings, they are in good condition. Yes I should probably flush the oil a second time. But this noise was there before the oil flush.

4) Will do, thank you!

Interesting, yeah it does sound like a mechanical issue - which is common on these diffs as they unfortunately are known to fail. But again it is hard if not impossible to diagnose the issue without hearing the sounds and being there.

[Kikerose]

Originally Posted by F87source

Interesting, yeah it does sound like a mechanical issue - which is common on these diffs as they unfortunately are known to fail. But again it is hard if not impossible to diagnose the issue without hearing the sounds and being there.

Thank you! I'll try to record it and upload it here.

Thank you so much for your time, really appreciated!

[Kikerose]

Here's the video of the knock:

https://www.youtube.com/shorts/pxLRIaj3ls0

I found this video where it explains the same issue I'm having and is exactly the same noise.

Looks like the fix is in this PDF:

https://f87.bimmerpost.com/forums/at...1&d=1614277505

May should go to BMW service and ask if this is a design problem and what can we do about it.

[F87source]

Oh yeah this issue, I haven't heard about this too frequently so I thought it was the brake shields.

But if indeed your issue is confirmed to be the play between the drive shaft it is a design flaw, and you'll need to do the repair like bmw states. There's nothing much that can be done other than that.

[Tigerino]

Hi there

I have a 2017 M2 6MT LCI

My car has developed a noise coming from the rear of the car
It seems to occur mostly when going over bumps - not changing gear or accelerating/braking

In fact, I can recreate it just be rocking the car as it sits

I haven’t had a chance to raise it and feel the play in the drive shaft

Has anyone had any experience with a noise similar to this? Did your diff issue seem to occur in circumstances of positional change in the car as well?

Thank you very much!

[Sel91]

I had the same thing with mine, 2017 build DCT. When getting on or off gas you hear a clank sound, loudest in 1-2. My diff was also sweating on the right side, I ended up getting a revised diff and the problem is gone now. These diffs are known to fail.