Lots of clunking that sounds like it's coming from the differential.

[coloradoe92m3]

[QUOTE=coloradoe92m3;15748875]Everyone is has different sensitivity but on page 55 of M3 supp. Manual its says "drive train clacking is normal on and off load". And yes it says clacking

[ec_E92]

[QUOTE=coloradoe92m3]

Originally Posted by coloradoe92m3

Everyone is has different sensitivity but on page 55 of M3 supp. Manual its says "drive train clacking is normal on and off load". And yes it says clacking

Well Mr. WebMD, since you felt the physical "thud" that my car experiences, you must be right.

[coloradoe92m3]

Read the manual. Its not my word. You tell me what page 55 refers to them?

[808MGuy]

Originally Posted by coloradoe92m3

Read the manual. Its not my word. You tell me what page 55 refers to them?

If it was normal, I should have been hearing this since I owned the car. Something has definitely happened to make it show up all of a sudden after 76k miles. I know there is a certain amount of noise inherent to the system but I don't think this is what that is.

[ec_E92]

Originally Posted by coloradoe92m3

Read the manual. Its not my word. You tell me what page 55 refers to them?

I believe neither the OP nor myself are complaining about a little drivetrain noise. We are both experiencing a symptom that has gradually been growing in magnitude. I think we have both made it clear we understand this car has a mechanical diff that makes some noise. We are experiencing something beyond that and searching for root cause. His indy shop didn't want to touch it, my indy shop said "You're diff is bad, $4k to replace". As a mechanical engineer I refuse to accept that answer, especially after dropping the pumpkin to open it up and inspect, open up my CV joints to inspect/clean/grease and check all bolt torque specs. So next area to check is tranny mounts and guibo. 2008 with 80k, not out of the question.

There has been some good technical, well-thought out symptom diagnosis here so please tell me what credentials you have to say "RTFM, its normal."

[geneatals]

vid clip?

[ec_E92]

Originally Posted by 808MGuy

Mostly when rolling idle and then getting back on the gas or in low gear and getting off the gas. Seems like it's related to load transfer. I thought maybe its the infamous broken bolts but I got under the car and didn't see any signs of broken bolts and no signs of the differential hitting anything around it. Does this mean the internals of the differential are pretty much done?

I just changed the oil in the differential and the DCT transmission and had it analyzed by Blackstone. The differential oil had about 41k miles on it and the DCT fluid had about 76k miles on it. Both came back with no issues.

Weekend Update: Looked under car again and front poly diff mounts appeared "squashed" and it looks like the diff was able to "walk" forward a bit. Checked torque on rear mounting bolt and it was a little loose. My guess is when diff mounts were installed rear bolt was bound up a bit and didn't get snugged up properly.

Bolt properly torqued and everything is nice and tight/quiet now. Even passed my wife's NVH test which is a pretty high standard.

[Raypan]

If the diff bushes were squashed, I would consider changing those as well.

[BPMSport]

Just heard back from the dealer on my diff. They performed the SIB, replaced the input seal and greased the flange per the SIB and the noise is still there. They said the diff needs to be replaced now...

Oh the joys..

[dparm]

Originally Posted by Mike Benvo

Just heard back from the dealer on my diff. They performed the SIB, replaced the input seal and greased the flange per the SIB and the noise is still there. They said the diff needs to be replaced now...

Oh the joys..

Time for a new LSD, yes?

[thegeneral101]

Originally Posted by Mike Benvo

Just heard back from the dealer on my diff. They performed the SIB, replaced the input seal and greased the flange per the SIB and the noise is still there. They said the diff needs to be replaced now...

Oh the joys..

no kidding!? What failed in the diff?

[ec_E92]

Originally Posted by Mike Benvo

Just heard back from the dealer on my diff. They performed the SIB, replaced the input seal and greased the flange per the SIB and the noise is still there. They said the diff needs to be replaced now...

Oh the joys..

Mike, I had my input bearings go bad but that just caused a metal-on-metal bearing noise. I'll post pics of my torn down diff and video tomorrow, maybe it can help.

[Time Lord]

any updates on this from anyone that posted?

[Groundpilot]

In my case, it turned out to be a simple problem. My x-pipe was installed incorrectly, and it was touching the heat shield.

[Time Lord]

Originally Posted by Groundpilot

In my case, it turned out to be a simple problem. My x-pipe was installed incorrectly, and it was touching the heat shield.

so you were getting a rattle?

I meant how was the power difference? Did you notice any? probably a dumb question lol

[RomanK]

Hello Guys..

Already wrote in other threads... But seems that it should be here...

I have the bumps from my rear subframe when I push/release the throttle.

I already changed right half-axle, rubber flex disc, constant-velocity universal ball joint, left flange of differential.
Today I changed the constant-velocity universal ball joint on left half-axel... Taken from my right half-axle because it was good.

I took my GoPro and recorded some videos to find the problem. Here is what I recorded.

1. See on half-axle.:

2. Here is my BIG problem what I am wanted to fix. See and try to hear the bumps on the 39 sec. Bumps when I push the throttle. I think it is the same like on first video.

Moreover my Visko Lock works perfect. Please, help me to fix this problem.

[DreamTime]

Yes, this sound. It kinda scared the crap out of me after I first noticed it. Once it was determined it was the differential I swapped out the fluid for the FM booster one, but I have not noticed any significant difference in the clunking. Many BMW mechanics have told me the sound is normal, and that I should not worry about it. A mechanic from the local dealership told me it was caused when the load is reversed to the rear of the car. I guess this is true?

[RomanK]

Originally Posted by DreamTime

Yes, this sound. It kinda scared the crap out of me after I first noticed it. Once it was determined it was the differential I swapped out the fluid for the FM booster one, but I have not noticed any significant difference in the clunking. Many BMW mechanics have told me the sound is normal, and that I should not worry about it. A mechanic from the local dealership told me it was caused when the load is reversed to the rear of the car. I guess this is true?

Yes it is true... Even if it is normal... I am really dissapointed of it. It is really bad feeling in daily drive. It is simple not ocnvenient when I open a throttle and get a kick to my ass.

Moreover it is bad twise... I don't know how it fix. There are no any options... Only changing the differential.

[pbonsalb]

Are you sure there is no play in your rear suspension bushings? I could easily twist my rear toe arms back and forth with my bare hands until they hit metal, Replaced them and can barely twist them at all now. I replaced my rear subframe bushings with 75D poly and the rear end is much more planted now -- no wiggling or jiggling. At the same time, I did the diff bushings in 95A so it is not moving as much. The rear diff bushing is a 1 inch aluminum piece with 1/4 inch of foam around it so there is definitely some play in it.

I will say that after tightening up my rear end, I hear a little diff whine from 65-75 mph from the stiffer diff bushings and actually a little more drivetrain noise of the clunking type from the driveshaft and maybe axles. But mine is not bad and does not bother me.

It is possible your problem is inside of your differential -- I don't know. I had not read of internal diff problems with these cars although I have read that the visco limited slip may wear out over time. I recently drove a 135i with an aftermarket helical limited slip and that diff definitely clunked noticeably.

[RomanK]

Originally Posted by pbonsalb

Are you sure there is no play in your rear suspension bushings? I could easily twist my rear toe arms back and forth with my bare hands until they hit metal, Replaced them and can barely twist them at all now. I replaced my rear subframe bushings with 75D poly and the rear end is much more planted now -- no wiggling or jiggling. At the same time, I did the diff bushings in 95A so it is not moving as much. The rear diff bushing is a 1 inch aluminum piece with 1/4 inch of foam around it so there is definitely some play in it.

I will say that after tightening up my rear end, I hear a little diff whine from 65-75 mph from the stiffer diff bushings and actually a little more drivetrain noise of the clunking type from the driveshaft and maybe axles. But mine is not bad and does not bother me.

It is possible your problem is inside of your differential -- I don't know. I had not read of internal diff problems with these cars although I have read that the visco limited slip may wear out over time. I recently drove a 135i with an aftermarket helical limited slip and that diff definitely clunked noticeably.

I have solid aluminium subframe bushings and delrin differential bushings... And one month ago I replaced 6 arms in rear suspension... so there is no play...

[RomanK]

Who knows, this is normal or not?

[DreamTime]

Originally Posted by RomanK

Yes it is true... Even if it is normal... I am really dissapointed of it. It is really bad feeling in daily drive. It is simple not ocnvenient when I open a throttle and get a kick to my ass.

Moreover it is bad twise... I don't know how it fix. There are no any options... Only changing the differential.

If it is normal, then it wouldn't bother me at all. I really just want to make sure I have done all the research I can before completely writing off loud clunking noises coming from my rear axle as normal.