Is it the Diff?

[elrichmeister]

Hi Everyone,

Well i had my driveshaft rebuilt a few weeks ago and about week after, i noticed a loud clicking/banging noise under the center console, during 1st gear launch (flame suit on). Weird thing it only happens sometimes.
I took it back to the shop that had my driveshaft rebuilt, they checked, guibo, u-joints, center support bearing and everything was nice and tight, no visible scraping or anything.
Now the diff on the other hand has a lot of play on input and output shafts, there is a audible clunk and play, the car has 174k miles and i don't have anything in the history in terms of any work done to it.
I did see this visibly at the shop when it was on the lift.

The shop is saying all the slack the drive shaft had before was probably taking some of the impact.

Here is a video i took of the noise, please excuse the dark video. Took this video before taking to the shop, so i wasn't sure what was making the noise.

https://www.youtube.com/shorts/cnyh8Dbc2NY?si=iap_q3JDDAijJT1z

Any opinions on the noise? can a diff make that noise? Other than that, the car feels fine, it does have some clunks on initial engagement, but when the car is in motion it feels fine.

[nextlvel]

What are the state of the diff bushings? As someone who has taken their diff out 3 times due to weird noises I will say it sounds like diff is either A) moving around due to loose front bolt or worn bushings or B) the diff has a good amount of play internally. The easiest way to check would be a clutch dump and see how it sounds imo.

[elrichmeister]

What are the state of the diff bushings? As someone who has taken their diff out 3 times due to weird noises I will say it sounds like diff is either A) moving around due to loose front bolt or worn bushings or B) the diff has a good amount of play internally. The easiest way to check would be a clutch dump and see how it sounds imo.

The diff bushings are pretty new and looked fine. I did a subframe reinforcement last year and replaced the diff bushings. Only has like 7k-8K miles on them. When i went on a test drive with the shop, we tried a clutch dump, it really only makes that noise when the car gets grip and squats, im assuming that when a lot of load is sent to the drive train.

[bigjae46]

What do they mean by play in the diff? If they are spinning the driveshaft by hand and notice that there is slack before the wheels turn then that is normal and your shop is likely incompetent. That play is normal lash in the gears. If you can wiggle the diff input or output shaft by hand then your diff is beyond fubar'd and why would you just rebuild the driveshaft and not address the diff?

It is the driveshaft.

[elrichmeister]

What do they mean by play in the diff? If they are spinning the driveshaft by hand and notice that there is slack before the wheels turn then that is normal and your shop is likely incompetent. That play is normal lash in the gears. If you can wiggle the diff input or output shaft by hand then your diff is beyond fubar'd and why would you just rebuild the driveshaft and not address the diff?

It is the driveshaft.

They spun the drive shaft and wheels by hand and mentioned that the slack was quite excessive. I did see slack when the wheels where spun, there was visible slack when one wheel was spun and the other wheel and would start move.
It was mentioned to me in the past that the diff may need a rebuild, but never noticed anything other than what i thought was m-clunk, only after the drive shaft rebuild i got this noise on a launch.

The drive shaft was rebuilt as the shop mentioned that there was a lot play and slack in the drive shaft during some routine maintenance and inspection, they recommended that i can have it rebuilt. I just decided to go for it since the car was there. I did recently have my driveshaft rebuilt on my other non-m e46 at this shop, so i had no issues with getting some additional work done to the car.

I think ill have them inspect everything again before taking the plunge on a Diff rebuild.

Thanks for the responses, i really appreciate it.

[sapote]

They spun the drive shaft and wheels by hand and mentioned that the slack was quite excessive.

Like how much, 90 or 180 degree free rotation? Normal stock spider gears have a lot of plays, easily the wheel can rotate 45* freely.
One cannot read the diff input shaft plays by rotating the input until the output flanges are rotating, as this includes both pinion/ring plays (very small) and spider gears plays (very large). It needs a special feel to detect the pinion/ring plays from rotating the input.

[elrichmeister]

Like how much, 90 or 180 degree free rotation? Normal stock spider gears have a lot of plays, easily the wheel can rotate 45* freely.
One cannot read the diff input shaft plays by rotating the input until the output flanges are rotating, as this includes both pinion/ring plays (very small) and spider gears plays (very large). It needs a special feel to detect the pinion/ring plays from rotating the input.

They were moving the wheels small degree and you can hear clunks in the diff where they were moving back and forth, they mentioned the slack was pretty bad and worst they've seen with e46 M3's.

What i really want to know, if the noise in the video posted can be made from the diff? only thing that has changed was the rebuilt driveshaft and the center support bearing. From what i know the M3 drive shaft has a CV joint, im assuming that its refurbished or reworked during a drive shaft refurb, could the noise be done by CV Joint, maybe something wrong with that. As the noise seems to come from under the center console like under or behind the arm rest.

I will try to schedule appt with the shop so they can do a more thorough look, before i jump and refurb the diff as its pretty expensive.

[sapote]

They were moving the wheels small degree and you can hear clunks in the diff where they were moving back and forth, they mentioned the slack was pretty bad and worst they've seen with e46 M3's.

This is normal to hear clunk in the spider gears when doing this. Normal.

I played the video again, the crunching noise is sure not from the diff. Yes, it sound more like driveshaft bad CV joint, or a big cracked floor mounted to diff subframe.

[elrichmeister]

This is normal to hear clunk in the spider gears when doing this. Normal.

I played the video again, the crunching noise is sure not from the diff. Yes, it sound more like driveshaft bad CV joint, for a big cracked floor mounted to diff subframe.

I really hope its not RACP, but its super coincidence if it were since the noise only appeared when refurbed the drive shaft. I just did RACP reinforcement plates last year with Kaiv. Ill be taking it back to the shop.

[Kcalhoun27]

Before i refreshed my diff, it made a bunch of noise, like it was about to fall out. I checked the mount bolts, the mounts, the bushings, the driveshaft, guibo, csb, everything. The diff was shot and it was the problem. Fixing things around it exacerbated the issue. Now that i put new clutches in it and all that, its nice and quiet. Never had a diff be that much of a drama queen before but now i know

[elrichmeister]

Before i refreshed my diff, it made a bunch of noise, like it was about to fall out. I checked the mount bolts, the mounts, the bushings, the driveshaft, guibo, csb, everything. The diff was shot and it was the problem. Fixing things around it exacerbated the issue. Now that i put new clutches in it and all that, its nice and quiet. Never had a diff be that much of a drama queen before but now i know

DId you get chance to listen to the video. Did you hear any noise like it? Other than some clunking when initially engaging movement, i dont hear anything else. The noise in the video was only from a relatively hard launch, not clutch dump (i think), but hard acceleration, the car squats no wheel spin and the nasty noise. I think its more of the CV joint on the rebuilt drive shaft, as i had no issues like these before the work.

[Kcalhoun27]

DId you get chance to listen to the video. Did you hear any noise like it? Other than some clunking when initially engaging movement, i dont hear anything else. The noise in the video was only from a relatively hard launch, not clutch dump (i think), but hard acceleration, the car squats no wheel spin and the nasty noise. I think its more of the CV joint on the rebuilt drive shaft, as i had no issues like these before the work.

Yes i did and yes thats similar. I had noise from launch and not much else. I know the m-clunk is a thing but it wasnt that and i dont think yours is either. As i said, my guess is that fixing the other stuff made the diff sound worse and now that its just from the diff slop, you can trace the sound better. Just my guess based on my personal experience, but now my diff is mostly quiet.
i rebuilt it with parts from diffsonline and was pleased. It wasnt too hard to do, assuming you have the tools and space. They have a clear how to video on their website iirc

[Nate047]

I mean… If a shop did this job, and the problem only occurs now after they worked on the car, I would straight up just bring it back and tell them diagnose and fix the problem they created.

[elrichmeister]

Yes i did and yes thats similar. I had noise from launch and not much else. I know the m-clunk is a thing but it wasnt that and i dont think yours is either. As i said, my guess is that fixing the other stuff made the diff sound worse and now that its just from the diff slop, you can trace the sound better. Just my guess based on my personal experience, but now my diff is mostly quiet.
i rebuilt it with parts from diffsonline and was pleased. It wasnt too hard to do, assuming you have the tools and space. They have a clear how to video on their website iirc

Thanks for the response, yea unfortunately i don't have space to tackle this my self, so i usually have a shop do the work for me.

I mean… If a shop did this job, and the problem only occurs now after they worked on the car, I would straight up just bring it back and tell them diagnose and fix the problem they created.

Yea that's where I'm at now. Only issue is the Shop has stopped responding, I did ask for quote a few times for a diff rebuild, but haven't received an answer.

[bigjae46]

They spun the drive shaft and wheels by hand and mentioned that the slack was quite excessive. I did see slack when the wheels where spun, there was visible slack when one wheel was spun and the other wheel and would start move.
It was mentioned to me in the past that the diff may need a rebuild, but never noticed anything other than what i thought was m-clunk, only after the drive shaft rebuild i got this noise on a launch.

The drive shaft was rebuilt as the shop mentioned that there was a lot play and slack in the drive shaft during some routine maintenance and inspection, they recommended that i can have it rebuilt. I just decided to go for it since the car was there. I did recently have my driveshaft rebuilt on my other non-m e46 at this shop, so i had no issues with getting some additional work done to the car.

I think ill have them inspect everything again before taking the plunge on a Diff rebuild.

Thanks for the responses, i really appreciate it.

WTF. You'd have to lock the diff pinion in place to determine driveshaft play. BUT...what would cause the driveshaft to have play in it? The CSB and the CV joint - those can be inspected relatively easy. I think your shop doesn't understand that your limited slip diff has backlash between the ring and pinion gears which causes the driveshaft some free rotation or play.

Then they did a half-ass rebuild. The machine to dynamically balance a driveshaft is VERY expensive. Unless they sent the driveshaft out to be rebuilt and balanced - they really didn't do the biggest reason why someone would pay to rebuild a driveshaft - and that's balance it.