Grinding under hard acceleration

[Handy Man]

My M3 has developed a grinding noise under full throttle acceleration in 1st gear and sometimes 2nd gear. You can hear it and feel it through the chassis. It happens no matter whether the traction control is on or off. It is worse if accelerating in a corner. Crawing around undtherneith with flashlight didn't reveal any obvious culprit.

Any thoughts as to what it might be?

My initial thought was the differential, but maybe something in the tranny, or just something loose that is rubbing on the drive shaft?

Thanks in advance for any help.

[badbeef]

Check the differential bolts to the subframe. Mine just broke and its not unheard of for mt cars.

[Beemdog]

-driveshaft guibo worn out
-diff bolts
-broken motor mounts allowing torque shift of motor and drivetrain
-loose exhaust mount

Lots of things could be the culprit-- time to get this car up on a lift and inspect it more closely.

[thekurgan]

Guibo or center bearing is my guess.

[Handy Man]

Thanks for the tips. I'll get it jacked up tomorrow and check those items. What's the best way to diagnose a bad guibo or bearing?

[thekurgan]

Originally Posted by Handy Man

Thanks for the tips. I'll get it jacked up tomorrow and check those items. What's the best way to diagnose a bad guibo or bearing?

Check for play in the driveshaft near the center bearing and the guibo. Generally a bad guibo "looks" bad. The rubber starts to crack as it degrades. Both of these are inexpensive repairs.

[swift7]

Hey, did you ever figure out what was causing this? I'm having the same issue, thanks