135i MT Is my diff bad? Clunking sound

[Lewis Cosgrove]

I'm guessing the diff shouldn't make this noise? Also if you release the clutch quickly and not smoothly when changing gear there is a load clunk from the rear which could be related to the diff or perhaps the diff mounts or even the center driveshaft bearing? Just wondering if the diffs meant to be buttery smooth so I can try and track down the unsmooth shifts and clunk noise. Thanks guys!

[HawkeyeGeoff]

Originally Posted by Lewis Cosgrove

I'm guessing the diff shouldn't make this noise? Also if you release the clutch quickly and not smoothly when changing gear there is a load clunk from the rear which could be related to the diff or perhaps the diff mounts or even the center driveshaft bearing? Just wondering if the diffs meant to be buttery smooth so I can try and track down the unsmooth shifts and clunk noise. Thanks guys!

That's just driveline slop that you're showing in the video; it is normal.

I would look at the bushings on everything that's usually what causes a clunk....i've also seen exhaust bang around causing what seems like a driveline noise as well.

[Lewis Cosgrove]

I'm not sure, diffs are only meant to have a small amount of play. Am it seems the clunk is coming from the diff, hard to be exact tho. There is definitively something loose in the drive train as you can get it too clunk lifting the clutch sharply. Iv had a look before and the diff mounts and guibos look ok, could be the cv joints.

It sounds very similar to this when I do the same thing and the noise in this video was caused by excessive backlash in the diff.

[juld0zer]

Diff mounts rarely go on these cars if driven normally. Check using a prybar. I cant see the diff jumping around in the video so i doubt the bushes have failed.

Centre bearing can cause a vibration also while at motorway speeds. But if you can get the car on a hoist with an assistant inside, handbrake up and jolting the drivetrain like in your video you can have a listen around the heatshields where the centre bearing is located.

Video sound is usually softer than the actual sound too. Have you checked the drive shaft uni joints?

[Lewis Cosgrove]

I'm talking about the internal backlash of the diff not the mounts, the diff does seem to be mounted solid so theres no issue there. Theres no vibration at speed so the centre bearing is most likely ok.

This weekend I'm just going to start taking things apart so i can get a proper look, I'm sure the diff is the problem , ill make sure to check everything else first tho uni joints included.

[juld0zer]

Originally Posted by Lewis Cosgrove

I'm talking about the internal backlash of the diff not the mounts, the diff does seem to be mounted solid so theres no issue there. Theres no vibration at speed so the centre bearing is most likely ok.

This weekend I'm just going to start taking things apart so i can get a proper look, I'm sure the diff is the problem , ill make sure to check everything else first tho uni joints included.

Also check the CV (or whatever its real name is) where the prop shaft screws into the pinion, assuming you have an inserted shaft with the big 50mm nut? Or does your car have the bolted version?

[vtl]

Originally Posted by juld0zer

Diff mounts rarely go on these cars if driven normally. Check using a prybar. I cant see the diff jumping around in the video so i doubt the bushes have failed.

I'd say the rear diff mount is a very common thing especially on high km examples. My car had a torn rear diff bushing and looking at several cars (>150k kms) I've worked on recently they all had torn diff bushes as well.

Ruins the shift feel and you can feel the slop in the drivetrain getting on/off throttle

[juld0zer]

Maybe it is an MT thing. I blew the bushes on my manual 370Z back in the day. My DCT 135i is still on original bushes, 154,000km.

Are they oil filled? What do you replace them with? M3 versions im guessing

[vtl]

Originally Posted by juld0zer

Maybe it is an MT thing. I blew the bushes on my manual 370Z back in the day. My DCT 135i is still on original bushes, 154,000km.

Are they oil filled? What do you replace them with? M3 versions im guessing

Auto as well, and it was just a 188mm pumpkin.

It is a hollow rubber mount, diesels had a hydraulic mount

Front bushings I replaced with M3, rear the m3 bushing is too small and doesnt fit. I replaced with the F30 2/3 series bushing 33316792514 which looks a bit beefier.

http://www.1addicts.com/forums/showp...&postcount=167

[Traf]

Rear M3 bushing is longer tho, personally i went with whiteline bushings. Both subframe and diff, so far so good.

[Olgeezer1]

I hear a slight metallic clink from the rear end on abrupt take-offs. Only starting off, not noticeable shifting gears underway. Doesn't happen when I feather the clutch for a smoother take-off. It's always been there and from what I've heard it's a common issue with BMW manual transmissions and basically considered normal.

[HP Autosport]

Have you removed the driveshaft and inspect the splined portion? Somethings some HD grease at the end of the splined shaft is all you need. A worn out driveshaft joint can sometimes make a clicking sound as well.