Weird noise from rear of the M3

[swifty]

Ok so I finally decided to post this here since I had no where else to turn. Hope someone can shed some light here.

M3: 2013, DCT, 24k (kms), aftermarket Dinan exhaust


- About 2 weeks ago, once the temperature dropped here in Canada, I noticed that the car makes this strange "faint shuddering or vibration noise" early in the morning after it's been sitting in the cold overnight ... I didn't experience this last winter

- Can't say it's clunking tho cuz there's no metallic pinging sound

- The noise only lasts about 30 secs in the morning so I'm unable to replicate it at the dealership

- Heard it more clearly today as I put it into reverse for 10 feet right after pulling out of the garage and it was coming directly from the rear of the car

- The car made the noise even standing still after I had reversed

- Also 2 weeks ago, I had the oil changed at the dealership and had my winter tires put on


The only thing I can assume is it has something to do with the differential. However there is no sound the rest of the day. Only in the morning and lasts about 30 secs so not sure if that is true.

Nway, I read the following thread below today on the differential bolt breaking on our cars and it's scaring the hell out of me.

http://www.m3post.com/forums/showthr...=441119&page=2

Any feedback or help will be highly appreciated.

[Killerfish2012]

Need more information. A video recording of the noise would help. Also what are you doing when it's happening? Cold start, reverse, mild acceleration?

[swifty]

- The sound comes on right after cold start and once I start moving the car at parking garage speeds
- Yesterday I believe it came on even standing still but it was more pronounced once I put it into reverse

- Today's noise sounded more like a grinding noise than a shuddering noise
- Again I put it into reverse for 8-10 feet at extremely slow speed and the noise was even more pronounced
- Then drove off to work and it lasted a good minute or more before it subsided
- I hear it at low speeds though it could be present at higher speeds but the exhaust and the engine is too loud for me to discern if it's still making that noise.
- Made a recording today but not sure if it's clear ... will try to upload it soon

- There is no noise the rest of the day when I take it out for lunch or the drive back home form work

[1MOREMOD]

weird noises from your rear end are pretty normal during the holidays. girls dont do it though or they are out.

[thekurgan]

Sounds like differential plates. We get the complains here often when it gets cold. It's worth checking out if you feel it could be the bolt, but if it subsides once warmed up, then you have a normal condition.

Some folks opt for the friction modified diff fluid, but honestly, the noise is normal and the FM stuff can lessen the locking of the diff.

All of my M cars have had this, I've never used the FM stuff.

[swifty]

Originally Posted by 1MOREMOD

weird noises from your rear end are pretty normal during the holidays. girls dont do it though or they are out.

Lmao ... Our thanksgiving was last month but made me laugh nonetheless

Originally Posted by thekurgan

Sounds like differential plates. We get the complains here often when it gets cold. It's worth checking out if you feel it could be the bolt, but if it subsides once warmed up, then you have a normal condition.

Some folks opt for the friction modified diff fluid, but honestly, the noise is normal and the FM stuff can lessen the locking of the diff.

All of my M cars have had this, I've never used the FM stuff.

Ok thanks. That makes sense cuz I doubt they used the FM one. However, the diff fluid was done at 1200miles and last winter I didn't hear any noise of this type. Is it normal to hear that noise the following winter.

Again the noise only came on after the temperature dropped so this does make sense and it's better than the diff bolt breaking. Will be taking it to dealer tomorrow to check on the bolts.

[swifty]

Went to the dealer and watched the master tech go through all the bolts on the rear differential. No broken or loose bolts so far.

We went through the original service where the diff fluid was changed and they did use Part # 83222282583 which is the FM modified version.

Only option now is to leave it at the dealer next week overnight for the master tech to drive it after it's been sitting for over 10 hours cuz you can only hear it for the 1st 30 secs - 1 minute in the morning at very low speeds. Tried recording on my iphone but it wasn't very clear.

[playground]

Was going to say take a look at the diff, make sure its documented on service. On my previous BMW the rear diff was making noises since the day I delivered it. After 80,000km my diff bearings were shot and the gasket started to produce leaks. BMW refused to service it saying it was tampered with. But I had the diff only inspected at the same dealership...

[swifty]

Originally Posted by playground

Was going to say take a look at the diff, make sure its documented on service. On my previous BMW the rear diff was making noises since the day I delivered it. After 80,000km my diff bearings were shot and the gasket started to produce leaks. BMW refused to service it saying it was tampered with. But I had the diff only inspected at the same dealership...

Good point. Will get the service letter from them from my last visit.

Btw, did you diff make a noise constantly or just for a minute or more.

[kenwelch]

Originally Posted by swifty

- The sound comes on right after cold start and once I start moving the car at parking garage speeds
- Yesterday I believe it came on even standing still but it was more pronounced once I put it into reverse


- There is no noise the rest of the day when I take it out for lunch or the drive back home form work

If the noise (even if mild) occurs when the vehicle is standing still it is not the differential. When stopped there are no moving differential parts to create noise.
Have you been able to create the noise when stopped?

[apecush]

It isn't resonance from the exhaust system is it?

[Flying Ace]

Originally Posted by 1MOREMOD

weird noises from your rear end are pretty normal during the holidays. girls dont do it though or they are out.

never realized girls don't do it. So how do they compensate to get all that junk out? I suppose constant nagging is a byproduct of this...


Seriously now. OP, this noise only happens when you start from stationary, and going in reverse without turning?

[swifty]

Originally Posted by Flying Ace

never realized girls don't do it. So how do they compensate to get all that junk out? I suppose constant nagging is a byproduct of this...


Seriously now. OP, this noise only happens when you start from stationary, and going in reverse without turning?

It only happens when the car has been sitting in the cold over night or all day for more than 5 hours and lasts about 30 secs - 2 minutes max.

The noise comes on right after the car gets moving but is more prominent when you put it into reverse.

[swifty]

Finally figured out what was wrong and thank God it wasn't the diff.

Thanks again for all the feedback.

[OzCraig]

What was the cause?

[swifty]

I had installed another members OEM xpipe with test pipe prior to the noise issue. I believe it was coming fm the cats when cold or somewhere on the pipe. New akra evo was installed the other day and noise was gone

[OzCraig]

Good stuff! Thanks for getting back with the solution