Rear Axle/CV Bolts constantly loosen themselves. HELP!

[Scythe17]

Hey everyone, I wanted some advice/help regarding the issue I have had with my 2010 E93 M3 6MT.

Here's the story:
I broke it doing a burnout because I'm an idiot and didn't lift when I got wheel hop (my wallet was very very unhappy with me, especially since I had only just got the thing 3 months prior to breaking it). The list of stuff I broke that has been replaced is the following: Rear half of driveshaft, Passenger side rear axle and CV Boot, Parking brake cable, Rear Differential Cover (snapped the cast... didn't break any bolts but all that were removed from all parts were replaced with brand new ones.) Internals of the diff looked undamaged... I have no idea how...

Now the juicy bit, Many months and over $2700 later (lucky my uncle owns a shop and was able to give me a bit of a discount, this could've been worse) there remains an issue that it seems like nobody can solve. The bolts that attach the axle to the diff just will not stop unscrewing themselves, They have been torqued to spec every time, replaced twice with new ones, and we even ignored the information that the bolts did not need a thread locker and we tried some after the second set of new bolts also backed out. They will not stay tight.

The bigger problem is that this is my daily driver and as soon as 1 to 3 drives are over I know the bolts are loose. How? Because suddenly around any moderately sharp corner while under power at all the rear drivers side starts making a horrible *ZZZuh... ZZZuh... ZZZuh...* sound that sounds like metal on metal (probably the internals of the diff going, "OW OW OW! STOP!!!"). The sound does not happen as long as the clutch is in or the car is in neutral around corners and never occurs in a straight line. The sharper the corner, the sooner the sound starts and the louder it is, and will occur in any gear to my knowledge but I'm rarely going around a sharp enough corner in 5th or 6th gear to fully test that claim. It has been an ongoing issue for over 5 months now and I am so exhausted by this.

If anyone has any idea what could be the reason for why these bolts simply come loose for no reason or what to look for next time I get the thing on a lift... I would really appreciate the help. Also if there are any threads related to this kind of issue, feel free to link it and I will gladly take a look!

[Ajolives]

Originally Posted by Scythe17

Hey everyone, I wanted some advice/help regarding the issue I have had with my 2010 E93 M3 6MT.

Here's the story:
I broke it doing a burnout because I'm an idiot and didn't lift when I got wheel hop (my wallet was very very unhappy with me, especially since I had only just got the thing 3 months prior to breaking it). The list of stuff I broke that has been replaced is the following: Rear half of driveshaft, Passenger side rear axle and CV Boot, Parking brake cable, Rear Differential Cover (snapped the cast... didn't break any bolts but all that were removed from all parts were replaced with brand new ones.) Internals of the diff looked undamaged... I have no idea how...

Now the juicy bit, Many months and over $2700 later (lucky my uncle owns a shop and was able to give me a bit of a discount, this could've been worse) there remains an issue that it seems like nobody can solve. The bolts that attach the axle to the diff just will not stop unscrewing themselves, They have been torqued to spec every time, replaced twice with new ones, and we even ignored the information that the bolts did not need a thread locker and we tried some after the second set of new bolts also backed out. They will not stay tight.

The bigger problem is that this is my daily driver and as soon as 1 to 3 drives are over I know the bolts are loose. How? Because suddenly around any moderately sharp corner while under power at all the rear drivers side starts making a horrible *ZZZuh... ZZZuh... ZZZuh...* sound that sounds like metal on metal (probably the internals of the diff going, "OW OW OW! STOP!!!"). The sound does not happen as long as the clutch is in or the car is in neutral around corners and never occurs in a straight line. The sharper the corner, the sooner the sound starts and the louder it is, and will occur in any gear to my knowledge but I'm rarely going around a sharp enough corner in 5th or 6th gear to fully test that claim. It has been an ongoing issue for over 5 months now and I am so exhausted by this.

If anyone has any idea what could be the reason for why these bolts simply come loose for no reason or what to look for next time I get the thing on a lift... I would really appreciate the help. Also if there are any threads related to this kind of issue, feel free to link it and I will gladly take a look!

Never heard this before. I trust you checked to make sure you have the proper half shaft, left and right are different part numbers.

Are the reinforcement plates installed? There's should be some lateral play in the shaft, 1-2".

[Theodore]

I'm surprised you didn't mention that you broke and replaced one or both of your differential bolts that connect to the subframe. It's reported on this forum as the most common failure during a burnout. Could it be a broken diff bolt putting unusual strain on the axle causing the axle bolts to back out?





Images borrowed from e46m3tony. Check out this thread for more info on broken diff bolts.