e92 m3 6MT differential issues

[hotwired78]

how common are diff issues? I've seen some posts, but hard to quantify
my 09 e92 m3 6mt is having some worbling happening at 2k rpm. my indy shop has narrowed it down to the diff. they want to have the diff pulled and sent out to have the center bearing replaced, and to replace the bushings during the process.

current estimate is $2.3k to do all this... they just replaced my 2 rear wheel bearings as we chased down the noises on this car...

im not trying to keep chasing stuff $2k at a time. its insanity.

[gh0stE92M3]

What’s worbling? Is it clunking? Have you checked your drive shaft? The center bearing wears and makes a cow bell sound. Not sure if this is what might be going on. How many miles on the car? Also have you checked your diff bushings if they are stock they might be dust.

This worbling only happens at 2k or starts at 2k and progressively gets worse?

[omgzirra_exe]

probably loose diff bolt - would make clunking noise in the rear at low rpm.
probably CSB/Guibo - would make a cow bell noise at low RPM.

I would suggest doing your csb + subframe bushings + diff bushings while everything is off.. saves you money in the long run..

[hotwired78]

with all the work to replace the bushings, im told its about +$600 to just pull the diff and replace the bearing at the point.
1700 to o the bushings, +600 to pull the diff send it out and get a new center bearing put in.... so around $2300-$2400 total

[hotwired78]

the sound isn't a hard clunking, but at 2k rpm it sounds like something is loose, wobbling as you press the throttle. especially apparent if you're driving at 2k rpm in 4th gear. pretty hard to capture this on a camera, but will try to post a video.

[omgzirra_exe]

Originally Posted by hotwired78

with all the work to replace the bushings, im told its about +$600 to just pull the diff and replace the bearing at the point.
1700 to o the bushings, +600 to pull the diff send it out and get a new center bearing put in.... so around $2300-$2400 total

yeah that's pretty much the on going price just to do solid subframe bushings / diff bushing replacement..

but you can pull the exhaust off, and heat shielding to expose the driveshaft / csb and see if its making noises.

loose diff bolt is easy to inspect for.. just need the car off the ground which I'm sure your mechanic has done. if not get it checked.

i use to get a "clunk sound" when ever i was driving at low rpm that wasn't loud but audible. cause of that, sometimes it settled and never made a noise some how.

the diff it self breaking is very... hard to be honest. they are pretty stout from factory already, its usually the surrounding parts of the drive line that ends up causing issues..

even if you were to launch your car a lot, you'd probably break your driveshaft first before the diff goes out.

alternatively you can check the top of the rear shock mount and see if it gotten lose? idk if you have coilovers, but i once forgot to fully tighten down on it and it made a soft clunk sound lol.

[hotwired78]

diff bushings are shot, but do i really need to replace the driveshsaft bearing in the diff itself?

[driftflo]

Originally Posted by hotwired78

diff bushings are shot, but do i really need to replace the driveshsaft bearing in the diff itself?

no.

and if you do, there are 4 bearings (two for the pinion and two for the lsd) that should be replaced, or at minimum both for the pinion… never replace just one!!! but this is an expert job and only very few shops out there have the knowledge, shims and tools (that are not available from bmw as bmw does not do this, they replace the complete pumpkin) to do it right.
so if it is not really necessary (permanent whining noises) i would not have it done!

[tdott]

better to get a rebuilt diff from diffsonline imo.

Not sure I'd just any random place to replace the diff bearings, not alot of people can even do it. So unless they are an expert and have done it before and you have a good reference that can confirm their diff has been able to run noise free.

[Assimilator1]

Originally Posted by hotwired78

how common are diff issues? I've seen some posts, but hard to quantify
my 09 e92 m3 6mt is having some worbling happening at 2k rpm. my indy shop has narrowed it down to the diff. they want to have the diff pulled and sent out to have the center bearing replaced, and to replace the bushings during the process.

current estimate is $2.3k to do all this... they just replaced my 2 rear wheel bearings as we chased down the noises on this car...

im not trying to keep chasing stuff $2k at a time. its insanity.

Should be easy enough for any mechanic to determine if the noise is coming from the diff itself, bung the car up on the lift with someone in it. Start it up, and run it up to 2k rpm in 4th gear, then have a mechanic listen to the diff with a stethoscope, or by putting thier ear to a long screwdriver touching the diff casing at various points. Watch out for spinning things!!!

If the diff or one of it's bearings is noisy you'll hear it more loudly at the diff, than say at the rear hubs. If it's bad you'll feel the vibrations with the screwdriver method! (That's why I use that method). You can do this with the ctr prop (drive) shaft bearing too.