[Dahigi777]

So all of a sudden my 550i clunks really hard when I am driving and take my foot off the gas to coast. About half a second after I take my foot off the gas, probably about 75% of the time, and the few times that it doesn't do it, it happens as soon as I start to press the brake. Doesn't seem to matter what gear, but seems when the car is at lower rpms (pedaling around a parking lot) ita more likely to happen. Loud metallic clubk sound that can be felt inside the car, very cringey when it happens. Never noticed it until the last week or so. Aside from that, completely smooth gear changes and no slipping otherwise. Kinda seems like it either doesn't want to let go in time, or it trys to grab the next gear when its not supposed to. I had a shop drop the pan and do the filter and refresh some fluid about 15k miles ago. Haven't seen any leaks or anything and I know its a super pain to check the level without being equipped to do it. Seems to come from the center of the car, but can't really say if its transmission or maybe drive shafts. Anyone have any idea of quick fixes I could try or perhaps what to look for if I were to get it up on a lift? Appreciate it.

[chipguy]

I would check the flex discs and the bushings for the differential.

[Dahigi777]

Originally Posted by chipguy

I would check the flex discs and the bushings for the differential.

From my research flex disc's are similar to u-joints? Do they connect shafts to each other? Its a little tricky finding things in the workshop manuals but I'm gonna try to find it.

[chipguy]

No they are not u-joints. Search BMW rubber discs and you will see plenty of pictures. One disc connect the transmission to driveshaft and another connect the driveshaft to the differential.

[spielnicht]

+1 on the guibo. Those tend to go bad every 40-50K, so if it's never been changed, definitely a culprit. The rear diff [rear] bushing is also a common fault. That you should be able to see by just sliding under the car from the rear without even raising it. It's easily visible. The guibo will require removal of the entire exhaust and the heat shields. Not necessarily hard, but just a PITA. Both are DYI if you're handy enough on cars.

This guy does both in same video. I followed his instructions to the tick and had no issues.

[Dahigi777]

Awesome! Super helpful, I appreciate the info.

[Cali8055]

I noticed my diff bushing & rear guibo need replacement . But noticed it has 2 and mechanic said he’d recommend to replace both mind as well . Are they both the same size ? I search up and only “ rear” one pops up . Thanks

[550bye]

Originally Posted by Cali8055

I noticed my diff bushing & rear guibo need replacement . But noticed it has 2 and mechanic said he’d recommend to replace both mind as well . Are they both the same size ? I search up and only “ rear” one pops up . Thanks

I ordered the same one, compared the original side by side and they are identical.