Underbody Clunking/Knocking Noise

[tareemaa]

I have the same issue, I hear it when I first start off and when I switch from going forward and reverse, would def like to know what this is.

[jrxe92]

everyone has this problem. well it's not really a problem if everyone has it. just a symptom. it's like a rocking noise when you let off on slow speeds. take it to the dealer and they either won't know or they'll give you a list of POSSIBILITIES. i have an 09, my friend has 12. we both have it

[pkimM3r]

mine seems to have some sort of rattling or clunking coming from the exhaust i would say...the two black rubber mounts on the muffler were installed wrong. they have been installed correctly. the rattling is still slightly there but now i hear more of a thumping sound.....when i had test pipes, the metal piece (exhaust holder) towards the front that is bolted to the bottom of the transmission where the middle cover is was bent to fit the bolt onto the bracket just behind the primary cats. when i swapped back to stock, i forced fit the xpipe so that the holes would line up and bolted it down.....going to go unbolt it, let the exhaust hang naturally and bend back that piece of metal so that it aligns itself. i think since the front of the exhaust isnt lined up well, the whole rear doesn't want to sit right and is constantly moving around and adjusting itself when changing from cold to warm, when coming to a stop (no exhaust pressure moving the exhaust) and over bumps (most obvious). its annoying as hell and i hope when i do this it finally gets rid of the damn sound...i ordered new rubber mounting from tischer because i can't stand this shit anymore LOL.

anyone else have this noise from exhaust moving around so much from underneath the car?

i dont think its a broken diff bolt because if it was, it just survived some major track duty so i think i can safely say it is that. everytime after the track though, it seems something is loose again dammit.

[nyfg56]

Anyone figure this out? I get the exact sound people are describing in my newly purchased e90. The exact sound in this video

http://www.m3post.com/forums/showthread.php?t=871122

[Bhdien]

My car has the same problem as well. I ordered a new center bearing and Guibo, but haven't had the time to install it. From experience, my old e36 m3 had the same noise as well. I changed the center bearing and it solved the problem. Hoping its the same for my e90.

[AWDBooSTIn90]

anyone narrow this down, to the actual problem area(s), instead of replacing the entire driveshaft..

[RomanK]

Hello guys.

You are talking about this noise on low speeds... But I have the kick to my rear subframe when the load on the driveshaft changes from engine brake to accel on HIGH speed. I think it is there on low speeds as well, but I hear and feel it on high speed in M mode.. when I push my gas pedal after the engine brake.

I already changed several parts in transmission. The u-joint looks good. I feel the kick from rear subframe but can the dual mass flywhell be reason of this kick in rear subframe? I don't hear the noise on idle running, but I just don't know what I should do to fix it.

I already changed:
- both axle shafts
- insalled the LSD to my diffirential
- cv joint on my driveshaft
- flex disk guibo
- solid subframe and diffirential bushings.

Please help...

[Pig Farmer]

Just a thought... There's a Constant Velocity joint where the drive shaft attaches to the differential. They sometimes go bad, or need to be repack. The noise travels down the hollow drive shaft which makes it difficult to locate exactly where it is coming from. When it goes bad, it sound similar to two aluminum bats hitting each other. It has a slightly high pitch metallic sound. If you search the Internet, you'll find a BMW TIS related to this issue.


^ sorry, I must have been typing while you sent the last post.

Second edit... Disregard everything I said. I hadn't had my coffee and was "sleep posting".

[kamber]

RomanK, i'm telling you man, it's probably your u-joint. I had the same exact clunk as exhibited in the video linked a few posts above; changed out my entire driveshaft and it was completely eliminated. My old driveshaft's u-joint didn't visually "look" like it needed replacing or deficient, but it was more than likely the culprit.

Just because other people experience it only in low speed/gear and you happen to have it on all speeds/gears doesn't neccessarily mean the source of the problem is different; perhaps the way in which the u-joint is worn slightly differs from case to case, or has different harmonics/resonance from case to case. The main thinf is that you are experiencing audible and physically noticeable drivetrain lash when you come on/off throttle.

You can take a driveshaft with a known good u-joint (OEM) or 1-piece aftermarket (eliminates the u-joint) and swap it on to see for yourself once and for all. Id recommend doing that rather than constantly hunting/chasing down where exactlt your current driveshaft is deficient.

[RomanK]

Originally Posted by kamber

RomanK, i'm telling you man, it's probably your u-joint. I had the same exact clunk as exhibited in the video linked a few posts above; changed out my entire driveshaft and it was completely eliminated. My old driveshaft's u-joint didn't visually "look" like it needed replacing or deficient, but it was more than likely the culprit.

Just because other people experience it only in low speed/gear and you happen to have it on all speeds/gears doesn't neccessarily mean the source of the problem is different; perhaps the way in which the u-joint is worn slightly differs from case to case, or has different harmonics/resonance from case to case. The main thinf is that you are experiencing audible and physically noticeable drivetrain lash when you come on/off throttle.

You can take a driveshaft with a known good u-joint (OEM) or 1-piece aftermarket (eliminates the u-joint) and swap it on to see for yourself once and for all. Id recommend doing that rather than constantly hunting/chasing down where exactlt your current driveshaft is deficient.

I will try to hear the same sound like on video above.

But now I can tell that on the high speed it feels like my subframe kicks the body under acceleration, although it rigidly fastened to it. I even replaced 6 arms in rear suspension. But the kick to my ass still there..

I saw my u-joint and seems that it is good. I don't feel there some plays. I already replaced all other units in driveline, and i think it can be my flywheel but I am not sure at all....

Will be glad if it will be u-joint...

Is it really, that bad u-joint can look good and haven't a backlashes when I try to play manually??

[atopa2002]

Stop chasing this ,its normal esp with DCT.

[Loki Motorsports]

Mine has this as well. Although I do not agree that it is "normal." I also have a E36 that exhibits the same exact noise and conditions to when it happens. Mine happens mostly when changing directions at slow speeds, something is flexing that shouldn't be. Makes me think it's rear arms/bushings. But no actual idea! Keeping a watchful eye on this thread though.

[jlo0109]

I have experienced a clunk sound whenever I am shifting a little bit more aggressively. For me, the issue was with the bolt that holds the differential in place, one of them broke.

[RomanK]

Originally Posted by Loki Motorsports

Mine has this as well. Although I do not agree that it is "normal." I also have a E36 that exhibits the same exact noise and conditions to when it happens. Mine happens mostly when changing directions at slow speeds, something is flexing that shouldn't be. Makes me think it's rear arms/bushings. But no actual idea! Keeping a watchful eye on this thread though.

Only on slow speed? Is there some kick to rear subframe on the high speed when you push your gas pedal?

[Loki Motorsports]

Originally Posted by RomanK

Only on slow speed? Is there some kick to rear subframe on the high speed when you push your gas pedal?

Yes, only audible when at speeds less than 15 MPH I'd say. I have never heard it happen any faster than that. It doesn't FEEL like subframe movement, although it could be I suppose. My first guess if it's that, would be trailing arm bushings, or the arms themselves. I'm about ready to mount my gopro underneath my car in various places to help track down where the sound is coming from.

[ec_E92]

If anyone is trying to source a new driveshaft look at this ebay link:

https://www.ebay.com/itm/263554041615

Smoking deal for 6MT cars. I have no relation to seller, only that I bought the other one in stock to store in case I need it in the future. Also comes with guibo and CSB.

[RomanK]

Today I checked all my driveline. I pulled off my driveshaft. Driveshaft looks totally good. No play at all. But I noticed the play in my ring&pinion gear. Watch the video below. I think this is a reason of my problem... Sounds like I hear it from the salon. Totally the same kick. So that is why this kick does not progressive and I could't to find it so long.

[RomanK]

I took my diff and tried to compare it with another ... It seems that they are similar ..
I do not know where my problem is.

[Solo_M_Tech]

It's either 1. The universal joint. It wears out and creates slop in the driveshaft that you will notice at alower speeds, changing direction or letri g the clutch out at a stop. 2. Broken diff bolt or torn bushing.

I've seen both make similar, but distinctly different sounds. The drive shaft will make more of a tinging sound, like a metal baseball bat. The dif bolt or torn bushing will be more of a thud. like hitting a tree with a baseball bat.

Center support bearing will make a rotational "Thud thud thud" sound if it's actually torn as the driveshaft "flops" around inside what's left of the center support bearing outer housing.

[RomanK]

Originally Posted by Gears_and_Gasoline

It's either 1. The universal joint. It wears out and creates slop in the driveshaft that you will notice at alower speeds, changing direction or letri g the clutch out at a stop. 2. Broken diff bolt or torn bushing.

I've seen both make similar, but distinctly different sounds. The drive shaft will make more of a tinging sound, like a metal baseball bat. The dif bolt or torn bushing will be more of a thud. like hitting a tree with a baseball bat.

Center support bearing will make a rotational "Thud thud thud" sound if it's actually torn as the driveshaft "flops" around inside what's left of the center support bearing outer housing.

1) I replaced this parts:
- both axle shafts
- Changed stock GKN Viskolok to LSD from BMW M5 E39
- CV-joint of driveshaft.
- flex disk guibo
- some details in suspension like 6 arms.
I checked the U-Joint and center support bearing as well.

All this parts are good 100%. Nothing of this parts does not have any influence on my kick.

2) I installed the solid subframe and poly diff bushings. The diff bolts and bushings are good 100% too.


What do you think about dual mass flywheel? Can it be a reason? But I don't hear any noise from this side... Only kicks to my rear subframe.

[Solo_M_Tech]

Originally Posted by RomanK

1) I replaced this parts:
- both axle shafts
- Changed stock GKN Viskolok to LSD from BMW M5 E39
- CV-joint of driveshaft.
- flex disk guibo
- some details in suspension like 6 arms.
I checked the U-Joint and center support bearing as well.

All this parts are good 100%. Nothing of this parts does not have any influence on my kick.

2) I installed the solid subframe and poly diff bushings. The diff bolts and bushings are good 100% too.


What do you think about dual mass flywheel? Can it be a reason? But I don't hear any noise from this side... Only kicks to my rear subframe.

The kick you feel is from the solid bushing Imo. All of the drivetrain forces have nowhere to flex into, and that will make the noises more appearent. It's possible you have some slop in the flywheel and The new updated parts are making it more obvious.

[RomanK]

Originally Posted by Gears_and_Gasoline

The kick you feel is from the solid bushing Imo. All of the drivetrain forces have nowhere to flex into, and that will make the noises more appearent. It's possible you have some slop in the flywheel and The new updated parts are making it more obvious.

Kick is very obvious... I don't see from this forum that somebody complained about the kick after installing the solid bushings.

If it is dual mass flywheel, why I don't hear from it side any noises?