Differential clunk under sudden acceleration.

Siajoon · 03-28-2019, 12:27 AM

I tried searching before posting but could not find an answer.

When I do a sudden hard accleration I get a kick in the back, a loud clunk, just one initial clunk and that is all.

If I preload first and then floor it I get no clunk, it's only when I do a sudden hard acceleration. Is this normal?

Any thoughts would be appreciated.

amrazM · 03-28-2019, 01:29 AM

Diff. Bushings.

Seems obvious no? If you preload the diff the bushings are already loaded and the diff has already moved, suddenly acceleration is causing the diff to jump.

I suggest You get it checked out ASAP before you damage something. You probably could mount a go pro somewhere underneath to see if it is in fact the diff moving.

Siajoon · 03-28-2019, 09:15 AM

I suppose that makes sense, Maybe I should just try getting the diff bushings replaced regardless.

Only reason I haven't is because I was told they last atleast until 100k. Currently at 68k.

///M Power-Belgium · 03-28-2019, 09:33 AM

Quote:

Originally Posted by Siajoon

I tried searching before posting but could not find an answer.

When I do a sudden hard accleration I get a kick in the back, a loud clunk, just one initial clunk and that is all.

If I preload first and then floor it I get no clunk, it's only when I do a sudden hard acceleration. Is this normal?

Any thoughts would be appreciated.

# 162 => https://www.m3post.com/forums/showth...bushing&page=8

E92M3GA · 03-28-2019, 09:36 AM

I replaced my diff bushings with Poly and did solid aluminum subframe bushings and I still have a noticeable clunk coming from the rear. ( Driveshaft and guibo looked fine, but I know those are likely my next areas of concern or the diff itself)

RomanK · 03-28-2019, 12:50 PM

Did your clunk seems like you can hear here:

2:49
3:20
3:44
4:10

?

Need to use headphones to hear it.

BayE30 · 03-28-2019, 01:04 PM

Quote:

Originally Posted by RomanK

Did your clunk seems like you can hear here:

2:49
3:20
3:44
4:10

?

Need to use headphones to hear it.

lol took yer eyes off the road for 1 second at 0:45 and almost lost it.

Siajoon · 03-28-2019, 01:17 PM

Quote:

Originally Posted by RomanK

Did your clunk seems like you can hear here:

2:49
3:20
3:44
4:10

?

Need to use headphones to hear it.

I was literally to mesmerized by the sound of the motor and the track that I couldn't hear anything lol..

RomanK · 03-28-2019, 01:42 PM

Try to hear it when he push the throttle after the braking on minutes what I mentioned.

pbonsalb · 03-28-2019, 01:57 PM

Maybe the driveshaft?

R3dliner · 03-28-2019, 02:07 PM

If you tap the throttle in high gear/low speed do you hear a clunk?
Most types of clunking is associated with the U-joint on its way out. Those are not serviceable and need a driveshaft.

Siajoon · 03-28-2019, 02:22 PM

Quote:

Originally Posted by R3dliner

If you tap the throttle in high gear/low speed do you hear a clunk?
Most types of clunking is associated with the U-joint on its way out. Those are not serviceable and need a driveshaft.

No, usually lower gear higher rpms when I put the motor on its toes, and then I left off and then sudden accel it knocks

R3dliner · 03-28-2019, 02:27 PM

Quote:

Originally Posted by Siajoon

No, usually lower gear higher rpms when I put the motor on its toes, and then I left off and then sudden accel it knocks

When's the last time your motor mounts were replaced?

Siajoon · 03-28-2019, 02:32 PM

Quote:

Originally Posted by R3dliner

Quote:

Originally Posted by Siajoon

No, usually lower gear higher rpms when I put the motor on its toes, and then I left off and then sudden accel it knocks

When's the last time your motor mounts were replaced?

2,000 miles ago when I replaced my rod bearings at MRF...

Bartledoo · 03-28-2019, 07:39 PM

Well if you want to rule out your diff bolts and bushings just slide your legs under the rear of the car and press on the diff from different angles. It will be extremely obvious if you have a broken diff bolt or bushing.

I would at least check that before driving the car again. If it is a broken bolt/bushing you can destroy the mounting portions of your subframe if you keep slamming the diff around.

roastbeef · 03-28-2019, 07:42 PM

this could very well be your driveshaft as well, don't exclude that in your troubleshooting.

Siajoon · 03-28-2019, 08:23 PM

Quote:

Originally Posted by roastbeef

this could very well be your driveshaft as well, don't exclude that in your troubleshooting.

Scarying me :/ hoping it's nothing bad

Siajoon · 03-28-2019, 08:24 PM

Quote:

Originally Posted by Bartledoo

Well if you want to rule out your diff bolts and bushings just slide your legs under the rear of the car and press on the diff from different angles. It will be extremely obvious if you have a broken diff bolt or bushing.

I would at least check that before driving the car again. If it is a broken bolt/bushing you can destroy the mounting portions of your subframe if you keep slamming the diff around.

If it's a diff bolt I'm assuming there will be plenty of play in the diff ??

roastbeef · 03-28-2019, 08:27 PM

Quote:

Originally Posted by Siajoon

Scarying me :/ hoping it's nothing bad

driveshaft is an easier and potentially cheaper fix than the diff. plus, you could easily upgrade to the carbon one piece for just a few dollars more.

Bartledoo · 03-28-2019, 08:28 PM

Quote:

Originally Posted by Siajoon

If it's a diff bolt I'm assuming there will be plenty of play in the diff ??

For sure.

Siajoon · 03-28-2019, 08:59 PM

Quote:

Originally Posted by Bartledoo

Quote:

Originally Posted by Siajoon

If it's a diff bolt I'm assuming there will be plenty of play in the diff ??

For sure.

I poked it a few times with a pvc pipe and lightly pressed on it with my foot and it's solid as rock

Siajoon · 03-28-2019, 09:01 PM

I'm taking it to MRF possibly tomorow to get his analysis on the situation. Hoping it's nothing crazy as I just dropped some pretty pennies for actuators and bearings lol

03-28-2019, 12:27 AM	#1
Siajoon ///Majestic 1857 Rep 2,091 Posts Drives: 2011 E90 ///M3 Join Date: Jun 2010 Location: SoCal iTrader: (1)	Differential clunk under sudden acceleration. I tried searching before posting but could not find an answer. When I do a sudden hard accleration I get a kick in the back, a loud clunk, just one initial clunk and that is all. If I preload first and then floor it I get no clunk, it's only when I do a sudden hard acceleration. Is this normal? Any thoughts would be appreciated.
	Appreciate 1 ///M Power-Belgium63310.00 Tweet Quote

03-28-2019, 01:29 AM	#2
amrazM mTekMods 2139 Rep 2,899 Posts Drives: like a granny. Join Date: Jan 2010 Location: Manhatan iTrader: (1)	Diff. Bushings. Seems obvious no? If you preload the diff the bushings are already loaded and the diff has already moved, suddenly acceleration is causing the diff to jump. I suggest You get it checked out ASAP before you damage something. You probably could mount a go pro somewhere underneath to see if it is in fact the diff moving.
	Appreciate 1 Siajoon1856.50 Quote

03-28-2019, 09:15 AM	#3
Siajoon ///Majestic 1857 Rep 2,091 Posts Drives: 2011 E90 ///M3 Join Date: Jun 2010 Location: SoCal iTrader: (1)	I suppose that makes sense, Maybe I should just try getting the diff bushings replaced regardless. Only reason I haven't is because I was told they last atleast until 100k. Currently at 68k.
	Appreciate 0 Quote

03-28-2019, 09:36 AM	#5
E92M3GA New Member 0 Rep 5 Posts Drives: E92 M3 Join Date: Mar 2019 Location: Georgia iTrader: (0)	I replaced my diff bushings with Poly and did solid aluminum subframe bushings and I still have a noticeable clunk coming from the rear. ( Driveshaft and guibo looked fine, but I know those are likely my next areas of concern or the diff itself)
	Appreciate 0 Quote

03-28-2019, 12:50 PM	#6
RomanK Private First Class 46 Rep 135 Posts Drives: M3 Coupe E92 DCT Join Date: Dec 2013 Location: St. Petersburg iTrader: (0)	Did your clunk seems like you can hear here: 2:49 3:20 3:44 4:10 ? Need to use headphones to hear it.
	Appreciate 0 Quote

03-28-2019, 01:42 PM	#9
RomanK Private First Class 46 Rep 135 Posts Drives: M3 Coupe E92 DCT Join Date: Dec 2013 Location: St. Petersburg iTrader: (0)	Try to hear it when he push the throttle after the braking on minutes what I mentioned.
	Appreciate 0 Quote

03-28-2019, 01:57 PM	#10
pbonsalb Lieutenant General 5228 Rep 10,611 Posts Drives: 18 F90 M5, 99 E36 M3 Turbo Join Date: Feb 2011 Location: New England iTrader: (4)	Maybe the driveshaft?
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03-28-2019, 02:07 PM	#11
R3dliner Lieutenant Colonel 935 Rep 1,930 Posts Drives: 18 M3 6MT Join Date: Mar 2016 Location: NYC iTrader: (5)	If you tap the throttle in high gear/low speed do you hear a clunk? Most types of clunking is associated with the U-joint on its way out. Those are not serviceable and need a driveshaft.
	Appreciate 0 Quote

03-28-2019, 07:39 PM	#15
Bartledoo Driver 2692 Rep 2,714 Posts Drives: 2011 E90 M3 6MT Join Date: Aug 2015 Location: Seattle, WA iTrader: (0) Garage List 2023 Corvette Stingray [0.00] 2002 Porsche Boxster [0.00] 2011 E90 M3 [0.00] 2021 Tesla Model Y [0.00]	Well if you want to rule out your diff bolts and bushings just slide your legs under the rear of the car and press on the diff from different angles. It will be extremely obvious if you have a broken diff bolt or bushing. I would at least check that before driving the car again. If it is a broken bolt/bushing you can destroy the mounting portions of your subframe if you keep slamming the diff around.
	Appreciate 1 Siajoon1856.50 Quote

03-28-2019, 07:42 PM	#16
roastbeef Lieutenant General 11585 Rep 12,725 Posts Drives: E92 M3 Join Date: Nov 2010 Location: Orange County, CA iTrader: (4)	this could very well be your driveshaft as well, don't exclude that in your troubleshooting. __________________ Instagram; @roastbeefmike
	Appreciate 1 Siajoon1856.50 Quote

03-28-2019, 09:01 PM	#22
Siajoon ///Majestic 1857 Rep 2,091 Posts Drives: 2011 E90 ///M3 Join Date: Jun 2010 Location: SoCal iTrader: (1)	I'm taking it to MRF possibly tomorow to get his analysis on the situation. Hoping it's nothing crazy as I just dropped some pretty pennies for actuators and bearings lol
	Appreciate 0 Quote