Clunk noise! Need help..

[JetBlack_M3]

What's happening guys. Up until 3 weeks ago my car started making a clunking sound upon acceleration like a baseball bat banging against the shaft. Even when in cruising speed, pressing and decompressing the gas pedal, I can hear a clunk sound anytime I let off. My driveshaft was inspected and was apparently in good condition.

I'm running Turner solid Delrin diff. bushings and I'm assuming they put a ton of stress on my differential and damaged it. Could this issue be from the u-joint on the driveshaft or a diff. Issue.

I included a video link down below so you guys can get an idea. Even with the driveshaft disconnected, it still made this sound. Assuming my diff is bad? Car is a 6MT

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[SAMM3Y]

Check for a broken diff bolt.

[JetBlack_M3]

Originally Posted by SAMM3Y

Check for a broken diff bolt.

Ill give it a look tomorrow

[Scores]

Originally Posted by boussi33

Ill give it a look tomorrow

I just replaced my broken one. It definitely sounded like you're describing but I thought solid differential mounts were supposed to fix that?

[JetBlack_M3]

Originally Posted by Scores

I just replaced my broken one. It definitely sounded like you're describing but I thought solid differential mounts were supposed to fix that?

They are but they also allow no play for the differential, leaving all the power going straight to the diff. I believe they might've put a ton of stress on it and damaged it.

[Scores]

Originally Posted by boussi33

They are but they also allow no play for the differential, leaving all the power going straight to the diff. I believe they might've put a ton of stress on it and damaged it.

What's causing all your flex? Broken motor mounts?

[nyc_dude]

When I replaced my driveshaft, the noise was a hollow metallic dink, since the driveshaft is hollow. The u-joint is not serviceable and wears. The center bearing is also a wear issue. You really hear the dink echo while driving in a parking garage.

Your sound might be the diff or half-shafts...but it could be the CV joint at the back of the driveshaft. The CV joint is packed with grease and ball bearings, and the grease eventually drys out, causing some noise.

If you need to replace any driveshaft component, replace the entire driveshaft with a Turner Motorsports unit. It has a replaceable u-joint. They don't have them in stock at their supplier in Az, so they have to make one from a used core. Labor to replace driveshaft components is the same as replacing the whole thing.

Best of luck,

Cheers

[JetBlack_M3]

Originally Posted by nyc_dude

When I replaced my driveshaft, the noise was a hollow metallic dink, since the driveshaft is hollow. The u-joint is not serviceable and wears. The center bearing is also a wear issue. You really hear the dink echo while driving in a parking garage.

Your sound might be the diff or half-shafts...but it could be the CV joint at the back of the driveshaft. The CV joint is packed with grease and ball bearings, and the grease eventually drys out, causing some noise.

If you need to replace any driveshaft component, replace the entire driveshaft with a Turner Motorsports unit. It has a replaceable u-joint. They don't have them in stock at their supplier in Az, so they have to make one from a used core. Labor to replace driveshaft components is the same as replacing the whole thing.

Best of luck,

Cheers

Thank you for the advice! We took down the driveshaft to see if the issue was from the differential or driveshaft and the diff continued to clunk as we rotated the wheels. I can assume at this point my diff is out. I got another diff with low miles. Hopefully it solves the issue

[jvictormp]

Originally Posted by boussi33

I got another diff with low miles. Hopefully it solves the issue

Nice!

Will you open the old diff and post pictures for us?

[JetBlack_M3]

Originally Posted by jvictormp

Nice!

Will you open the old diff and post pictures for us?

Of course! I'll be posting pictures of the process

[jvictormp]

Originally Posted by boussi33

Of course! I'll be posting pictures of the process

Apparently you opened other threads about the same problem.

I saw at one of them that you were getting wheel hop when spinning, right?

Then you went to the very extreme solid bushings that caused this problem, now you're turning back to OEM.

Do you think the wheel hop will be solved by the new OEM bushings? Shouldn't you try some intermediary option?

[bvrider1]

Good insight.

Solid bushings with wheel hop = Busted Diff.

Hope the OP can confirm what happened and get it back on the road.

Originally Posted by jvictormp

Apparently you opened other threads about the same problem.

I saw at one of them that you were getting wheel hop when spinning, right?

Then you went to the very extreme solid bushings that caused this problem, now you're turning back to OEM.

Do you think the wheel hop will be solved by the new OEM bushings? Shouldn't you try some intermediary option?

[JetBlack_M3]

Originally Posted by bvrider1

Good insight.

Solid bushings with wheel hop = Busted Diff.

Hope the OP can confirm what happened and get it back on the road.

Originally Posted by jvictormp

Apparently you opened other threads about the same problem.

I saw at one of them that you were getting wheel hop when spinning, right?

Then you went to the very extreme solid bushings that caused this problem, now you're turning back to OEM.

Do you think the wheel hop will be solved by the new OEM bushings? Shouldn't you try some intermediary option?

Before installing solid delrin diff mounts, I had the oem rubber mounts which were causing loads of wheel hop. I installed the solid mounts and wheel hop was eliminated. I also installed 295's in the rear. During that process, those components may have been too much stress for the diff, damaging the internals, causing it to clunk

[jvictormp]

Originally Posted by boussi33

Before installing solid delrin diff mounts, I had the oem rubber mounts which were causing loads of wheel hop. I installed the solid mounts and wheel hop was eliminated. I also installed 295's in the rear. During that process, those components may have been too much stress for the diff, damaging the internals, causing it to clunk

Oh, I see. Solid bushings + 295 width tires. Maybe our diff is not thaaat strong.

Is your engine stock?

[JetBlack_M3]

Originally Posted by jvictormp

Oh, I see. Solid bushings + 295 width tires. Maybe our diff is not thaaat strong.

Is your engine stock?

I'm full bolt ons at the moment. I'm just debating if I should rerun the solid mounts with my new diff or go back to the oem mounts. The solid mounts put the power to the ground

[pbonsalb]

Do you think damage could have been done from wheel hop while the old stock bushings were in place that you did not notice until after the solid bushings were installed?

[JetBlack_M3]

Originally Posted by pbonsalb

Do you think damage could have been done from wheel hop while the old stock bushings were in place that you did not notice until after the solid bushings were installed?

Good point! Wheel hop does damage the diff. I'm sure they served their part and the solid mounts just finished the job lol

[pbonsalb]

It the loss of traction and regaining traction during hop that shocks the diff and can break mounting bolts. I am curious what the problem is with yours but it may not be obvious without disassembly and some knowledge of how these diffs work. Is it a broken head tooth or axle spline or worn bearing or something is the lsd assembly.

[JetBlack_M3]

Originally Posted by pbonsalb

It the loss of traction and regaining traction during hop that shocks the diff and can break mounting bolts. I am curious what the problem is with yours but it may not be obvious without disassembly and some knowledge of how these diffs work. Is it a broken head tooth or axle spline or worn bearing or something is the lsd assembly.

I'm getting my new diff installed next week. We're gonna open both my broken one and new one. We'll have to wait and see how they compare

[DRLane]

@boussi33 All you posts reference the differential mounts being upgraded. What have you done with the subframe mounts? Are they also upgraded?

[JetBlack_M3]

Originally Posted by DRLane

@boussi33 All you posts reference the differential mounts being upgraded. What have you done with the subframe mounts? Are they also upgraded?

No sir. They're still oem

[pbonsalb]

Maybe the flex in them contributed to the problem. I would have done hard subframe mounts like 75D poly or Delrin or aluminum and not quite as hard diff mounts. I use 75D subframe and 95A diff, for example.