I am new here but have been lurking for quite some time. I have a 2004 M3 Laguna/black with a 6sd and have a clunking noise coming from the diff.

It only happens in first gear going no more than 5mph or 1000 RPM's, kinda like you are about to come up to a stop sign and need to stop and are going really slow.

So then I hit the clutch so I can stop without stalling and as the clutch engages I hear the clunking noise from the rear end.

Possible diff bolts loose, or need new fluid? I dont buy the whole "the M3 diff just makes noise" arguement. But is it true they just make noise? I have read other things it could be, but most of them were people making sharp turns or at high speeds.

I am going to take it to the dealer as it is still under warranty and have them take a look at it but wanted to get some opinions from everyone.

thanks

There is a SB concerning an upgrade to the Diff fluid, Make sure they change the fluid with the new product. I have the part number if you need it. My car "cluncked" to until they changed the diff fluid.
GandT

i`ve experienced the clunk noise on my car. When I checked the differential, I spotted my diff mounting defective. I sent it to the dealer and they change the diff cover as the mountings are one piece with the diff cover! have to changed the oil too..

I dont buy the whole "the M3 diff just makes noise" arguement. But is it true they just make noise?

:confused

Noise from drivetrain lash is normal.

+1 for some reason the M3's just have drivetrain noise.

When I checked the differential, I spotted my diff mounting defective.
What exactly was defective? I'd like to take a look myself first, if there is anything.


Noise from drivetrain lash is normal.

But at such low rpm's? not much torque is being produced at that point.

There is a SB concerning an upgrade to the Diff fluid, Make sure they change the fluid with the new product. I have the part number if you need it. My car "cluncked" to until they changed the diff fluid.
GandT
I could use the number and price if you know it.. I needa do that this week coming up. Is it expensive?

i replaced the diff cover, change the gasket and oil...The reason they change the diff cover is because the mounting is attched with the cover (not seperately).. and yes, even during low rpm between shifting it produced this loud clunk sound..

My car goes to the dealer next Monday for the same issue, also under warranty. I will post what they determine.

i replaced the diff cover, change the gasket and oil...The reason they change the diff cover is because the mounting is attched with the cover (not seperately).. and yes, even during low rpm between shifting it produced this loud clunk sound.

Was there something you could visually see when you looked or can it only be determined when you remove the cover?


My car goes to the dealer next Monday for the same issue, also under warranty. I will post what they determine.

Excellent, I am waiting for my rear view mirror to come in. When it does I am going to bring it in for that and the diff. noise, be nice to have some heads up before.

Thats just the normal clunk you are hearing. Most likely your car if its an 04 has the new differential fluid. The noise you would hear from bad differential fluid is probably more of a grind and usually does it when you are turning in tight radius.

Thats just the normal clunk you are hearing. Most likely your car if its an 04 has the new differential fluid. The noise you would hear from bad differential fluid is probably more of a grind and usually does it when you are turning in tight radius.


When did the change over happen, after MY03?

Not too sure on that. I think if you check your service record you will see if it has been changed or not. From what you described though it just seems like the typical M clunk. If you are in 1st gear and let off the gas at say 5 or 10mph you may hear the clunk again. Bmw leaves play or lash in the drive train for some reason.

Not too sure on that. I think if you check your service record you will see if it has been changed or not. From what you described though it just seems like the typical M clunk. If you are in 1st gear and let off the gas at say 5 or 10mph you may hear the clunk again. Bmw leaves play or lash in the drive train for some reason.
It's the ///M-Clunk differential.

Change your diff fluid... this is normal for E46's but just as a precaution I suggest changing your fluid.

kthxbai

Its just the fluid that BMW uses nothing to worry about... you can get it changed with i think its called redline or something like that usually takes care of the clunking

I was not satisfied with the "its normal" response, in the process of getting a new diff under warranty.

I was not satisfied with the "its normal" response, in the process of getting a new diff under warranty.

I am bringing the car in Friday for other a few other things including this.

So they said it was normal eh? How did you pull off the new diff.?

Sweet talk em? or refuse to leave until they gave you a new one? :)

I have a pretty good relationship with my SA, so it wasn't too bad. Most dealerships will insist that the clunk is completely normal......be polite and stand your ground. My point to them was that the car did not make such a horrid clunking noise when I bought it, so it is in fact not "normal".



I am bringing the car in Friday for other a few other things including this.

So they said it was normal eh? How did you pull off the new diff.?

Sweet talk em? or refuse to leave until they gave you a new one? :)

I have a pretty good relationship with my SA, so it wasn't too bad. Most dealerships will insist that the clunk is completely normal......be polite and stand your ground. My point to them was that the car did not make such a horrid clunking noise when I bought it, so it is in fact not "normal".

Cool, the SA I had last time was a nice guy and very helpful so I will try and track him down for my first point of contact, since he is handling a couple other smaller warranty issues I will ask for him.

I'll report back with updates tomorrow

Just got back from the dealer here and all went well as I expected. Unfortunately I got the usual explination of the drive train knock and that it is typical for the M cars. I still dont buy it because like Oxford and many others state it wasnt there from the start.

I dont have a long standing relationship with the dealer here (only been here for about 8 months) so even when I stood my ground they wouldnt budge. I still have about 4K miles or 7 months left on the warranty so I have some time to figure out what to do.

Other than that they were great, I am getting my rear window weather stripping on both sides, replaced under warranty as they are starting to dry rot.

Sorry to hear the news. How bad/loud is your diff clunk? Did they offer to change out the diff fluid to see if that would help? I believe there is a service bulletin about that, although it might have been for 01-03 cars, I'm not certain though.

Sorry to hear the news. How bad/loud is your diff clunk? Did they offer to change out the diff fluid to see if that would help? I believe there is a service bulletin about that, although it might have been for 01-03 cars, I'm not certain though.

I dont know what would be considered bad compared to yours, but I can hear the clunk, an audible one, when putting it into 1st or reverse from neutral. It doesnt do this all the time.

It is a bit louder (not by much) when I am engaging the clutch as described in the first post. It wont do this every single time, but it is tough to describe when it does happen.

Hell, even the SA that I had said his M3 does it too and that it is a typical clunk. I wanted to ask him under what circumstances it happens to him but when I went back to get it he wasnt around.

damn, I have the exact same noise/clunk with my mcoupe and my buddy who's a BMR tech says its normal. He event as far to say hat its worse on the E46 M3 and I would have accept it. Its an ///M car thing he says.

my question is do the smg cars have this clunk too?

my question is do the smg cars have this clunk too?
SMG driveline is identical.

Driveline clunk is normal, even when new. Sometimes it's worse because of a loose diff bolt, or because your guibo is worn. Check out the mounting bolts and inspect the guibo. If they're OK, the clunk is normal.

SMG driveline is identical.

Driveline clunk is normal, even when new. Sometimes it's worse because of a loose diff bolt, or because your guibo is worn. Check out the mounting bolts and inspect the guibo. If they're OK, the clunk is normal.

You brought up a good point, I had the service guy check out the differential mounting bolts and said they were fine.

I also inquired about the new diff fluid and he said he looked it up and the service bulletin that applied to it said that it was to cure a "whining noise" rather than a clunk.

what are some visible signs on the guibo, just cracking and dry rot?

Thanks

You shouldn't see dry rot on any E46 M3. Look for cracking or any other signs of damage.

FWIW, the clunking is clearly a "feature" of the M diff. The diffsonline unit that I have in the race car, both works better and is completely clunk free.