Drivetrain rattle has me stumped

[HDdave]

I have been trying to give life back to this 08 e90 that I bought a couple months ago, and this drivetrain noise is proving to be tougher to figure out than I initially thought.

It is a pretty loud metal to metal clanking noise. Worst under deceleration by a long shot, also bad in reverse, but also present in forward gears.

I got the car up in the air, dropped the exhaust and removed the heat shields, and its still hard to pinpoint. I am about 80% sure its coming from the center bearing, its very hard to get the car to do it without being under any sort of load. Everything spins freely enough when its on stands that the noise is very faint. The driveshaft appears to be new- so thats where I am a little worried. From the part numbers I think its a CRS automotive brand ( so basically autozone). Now I am not sure if thats a decent brand or not, but I am assuming as with most autozone style cheap parts- it just wont work right on our cars?

I ordered a used one form Mparts, just to get back to an OE shaft. I think I am going to try that one as-is when it gets here and not touch the center bearing. I thought about a carbon DS, but decided against spending $1800 when i'm still not sure thats the issue.

Only other scenerio I could see is something inside the transmission itself, which would be pretty not cool. But I did detatch the guibo and put the car back in drive/reverse on the jackstands and I didnt hear any noises at all so thats a good sign.

Attached is a video of the issue- I originally as you can see thought it was the flywheel rattling itself around. Let me know yalls thoughts please

https://youtube.com/shorts/KLVxpwvv8...9O0OevEiYioHNM

[nycplumber]

Did you check your heat/dust shield for a stuck rock or pebble?

Edit: just watched video, its definitely not that

[omgzirra_exe]

could be the CRS driveshaft, the DORMAN ones sold by autozone are actually really good

they are the same P/N as from the DriveShaft Specialist shop.

[HDdave]

Yeah I have checked everything else quite extensively.. Had the car in the air running in every different gear while laying under it no heat shield ect. Again- in the air the noise is very faint. Not so much on the ground.. I am not sure if the downward weight of the car- or the load of the tires spinning that causes it to get so much louder.

I suppose I could hook the shaft back up, put a jack under each rear spindle, and jack them up and run it?

[omgzirra_exe]

Originally Posted by HDdave

Yeah I have checked everything else quite extensively.. Had the car in the air running in every different gear while laying under it no heat shield ect. Again- in the air the noise is very faint. Not so much on the ground.. I am not sure if the downward weight of the car- or the load of the tires spinning that causes it to get so much louder.

I suppose I could hook the shaft back up, put a jack under each rear spindle, and jack them up and run it?

Just get the car high enough off the ground so you can safely get underneath it, put it in gear, and bring the RPMs up a bit.

You’ll probably need to turn DSC off too, otherwise the car may think it’s losing traction lol.

If it was rubbing along the centerline of the driveshaft, you’d almost definitely see marks on the chassis.