Slight clunk in very low speeds

[hatepotholez]

I have this slight clunk on initial take off and low speeds. The dealer couldn't find it the first time so I took it in again and then they changed the rear diff. That helped another clunk when putting the DCT in gear.

I then went for a drive with the foreman at another dealership as it was more convenient to meand obviously I couldn't replicate it.

I'm attaching a video, hopefully someone can chime in. I really hate rattles and clunks

[andrei.m4]

Welcome to bmw m world))

[hatepotholez]

Originally Posted by andrei.m4

Welcome to bmw m world))

Lol didn't happen on my other M3

[TheirThere]

i just finished the driveshaft recall.
the car would have a noticeable clunk/thud when changing gears under a fairly heavy load.

for some reason your youtube video is private.

[hatepotholez]

Originally Posted by TheirThere

i just finished the driveshaft recall.
the car would have a noticeable clunk/thud when changing gears under a fairly heavy load.

for some reason your youtube video is private.

They also did the driveshaft recall on my car, could be related. I changed the video settings, can you try now?

[TheirThere]

Originally Posted by hatepotholez

I changed the video settings, can you try now?

yep, it's viewable.

[conquistador714]

On my 6 speed I had a similar thumping at low speed in between gears. Turned out to be my diff bushing, at 23k miles. Best to get the car up on a lift and check all the basis.

[hatepotholez]

Originally Posted by conquistador714

On my 6 speed I had a similar thumping at low speed in between gears. Turned out to be my diff bushing, at 23k miles. Best to get the car up on a lift and check all the basis.

They did the diff bushings not too long ago. If they did blow again I would assume they wouldn't install a rear diff with bad bushings.

[andrei.m4]

Retorque diff nut(50mm one on the driveshaft cfk), but be carefully retorque it using istad procedure, according to them you need a new nut and some special loctitte 648. Torque at 120nm. You need to let loctitte to dry 3 hours etc, go to a service bmw and tell them to use istad procedure. I changed differential on my pocket like a stupid... and after 2 weeks sound again i just retorqued and thats it. Your welcome

[hatepotholez]

Originally Posted by andrei.m4

Retorque diff nut(50mm one on the driveshaft cfk), but be carefully retorque it using istad procedure, according to them you need a new nut and some special loctitte 648. Torque at 120nm. You need to let loctitte to dry 3 hours etc, go to a service bmw and tell them to use istad procedure. I changed differential on my pocket like a stupid... and after 2 weeks sound again i just retorqued and thats it. Your welcome

Thanks, I'll let them know.

[andrei.m4]

Bmw sucks with that nut, i don t know why they created this type of cfk mount to rear diff. But when i am thinking about crank hub rear dif nut is the smallest problem.

[hatepotholez]

Originally Posted by andrei.m4

Bmw sucks with that nut, i don t know why they created this type of cfk mount to rear diff. But when i am thinking about crank hub rear dif nut is the smallest problem.

Did you have the clunk all the time or sometimes?

[andrei.m4]

That nut can make noise when decelerating from 3->2 2->1 or put in reverse and accelerate. When the gear changes smooth clunk is not present but sometimes when dct make a wired gear change, jumpy downshift or how you want to say it can clunk once and then when you accelerate it will clunk one more time.

[hatepotholez]

Originally Posted by andrei.m4

That nut can make noise when decelerating from 3->2 2->1 or put in reverse and accelerate. When the gear changes smooth clunk is not present but sometimes when dct make a wired gear change, jumpy downshift or how you want to say it can clunk once and then when you accelerate it will clunk one more time.

Finally found a knowledgeable tech at the dealership. You were correct, they changed the nut and put the loctite and the clunk is gone.

Thanks so much!

[andrei.m4]

Your welcome i have also mine broken now but I can t unscrew it cause last time i inserted too much loctite...) i have a new one but i can t install it. Also if you have rough idle from time to time like a slow kick, misfire i found just some info, is related to alternator/system voltage.

[jaylazy2020]

Originally Posted by andrei.m4

That nut can make noise when decelerating from 3->2 2->1 or put in reverse and accelerate. When the gear changes smooth clunk is not present but sometimes when dct make a wired gear change, jumpy downshift or how you want to say it can clunk once and then when you accelerate it will clunk one more time.

That’s very similar to what I have noticed over last 5000 miles.

Only at very low rpm

The car is in with bmw next week to have very minor right hand side diff leak fixed

They will have to car for two days.

Could I direct them to change the bolt and re torque with loctite etc ?

It would epilinate this potential source

Thanks