Broken diff bolt poll

F82_SID · 03-22-2012, 08:57 PM

Hey there, we have been seeing so many differential bolts breaking lately that I just wanted to create a little poll to see what the degree of this problem is.

Shmelgy · 03-22-2012, 09:23 PM

Bullshit, had to pay $250 and get it fixed

THE TECH · 03-22-2012, 09:51 PM

I'd like to know what's causing it.

Grail05 · 03-23-2012, 08:02 AM

Quote:

Originally Posted by THE TECH

I'd like to know what's causing it.

same here but so far the people that had this issue is when changing removing and installing exhaust...

When i had my exhaust replaced. I did it myself and never took any bolt out i used WD40 to let the exhaust rubber loose, and so far no issue for me...

chmura · 03-23-2012, 08:20 AM

Quote:

Originally Posted by Sean05

same here but so far the people that had this issue is when changing removing and installing exhaust...

When i had my exhaust replaced. I did it myself and never took any bolt out i used WD40 to let the exhaust rubber loose, and so far no issue for me...

Yup that is exactly what I plan on doing. I guess it is critical for not taking that bolt out and IF someone does make sure it torqued properly.

There is really no point taking that hanger off. Just use some lubricant spray and a pry bar to get the rubber off the hanger.

Kyoshi71 · 03-23-2012, 08:27 AM

When I did my exhaust I never removed the diff bolt (mainly because it's unnecessary). However, removal and re-installing of those bolts is not the primary cause of this problem. Think about it: There's no alignment issue; there's no pre-loading issue; there's no disposable parts issue, i.e. crush collars. The only thing one would think is the problem is the torque spec, which in my opinion is highly unlikely because they are mountd via rubber bushings. It does effect many more 6MTs than DCTs and wheel-hops have been a known cause of the failure.

It's been said before that it's probably a combo of inadequate bushings, which allow the diff too much travel, coupled with inadequate tensile strength of the bolts.

Change the diff and sub-frame bushings - problem solved.

Boostin FD · 03-23-2012, 08:37 AM

Which bolt are you guys talking about? I did my exhaust myself... and i never took any differential bolts off.

DARK_M3 · 03-23-2012, 09:09 AM

Where's the "no" option in the poll?

Grail05 · 03-23-2012, 12:54 PM

Quote:

Originally Posted by Kyoshi71

When I did my exhaust I never removed the diff bolt (mainly because it's unnecessary). However, removal and re-installing of those bolts is not the primary cause of this problem. Think about it: There's no alignment issue; there's no pre-loading issue; there's no disposable parts issue, i.e. crush collars. The only thing one would think is the problem is the torque spec, which in my opinion is highly unlikely because they are mountd via rubber bushings. It does effect many more 6MTs than DCTs and wheel-hops have been a known cause of the failure.

It's been said before that it's probably a combo of inadequate bushings, which allow the diff too much travel, coupled with inadequate tensile strength of the bolts.

Change the diff and sub-frame bushings - problem solved.

I agree with you but most people that had this issue is when they removed that hanger. so i dont know... it sure is causing something....

Grail05 · 03-23-2012, 12:56 PM

Quote:

Originally Posted by Boostin FD

Which bolt are you guys talking about? I did my exhaust myself... and i never took any differential bolts off.

did you removed any hangers...?

Boostin FD · 03-23-2012, 01:00 PM

the one all the way in the back... You can see them through the rear bumper.

1MOREMOD · 03-23-2012, 01:09 PM

no i havent and have spent time screwing around on a skid pad as well as lots of track abuse. i get under there and check periodically if the are tightened up.

IrishCoffee · 03-23-2012, 01:27 PM

Quote:

Originally Posted by Sean05

same here but so far the people that had this issue is when changing removing and installing exhaust...

When i had my exhaust replaced. I did it myself and never took any bolt out i used WD40 to let the exhaust rubber loose, and so far no issue for me...

It's a serious pain in the ass removing and reinstalling the exhaust without removing the front hangers from the car. After reading all these posts I did it though because I didn't want to remove the nut that attatches to the diff bolt. A lot of wd-40 and muscle was necessary to pull the exhaust off the hanger. My forearms were really sore the next day.

In case this issue ever occurs and BMW ever tried to tell me that it was from installing the exhaust I took pictures of the front hangers on the car still without the exhaust.

saeedg48 · 03-23-2012, 01:30 PM

anyone have pics?!

M3PO · 03-23-2012, 05:17 PM

This is kinda scaring me. I think i may upgrade the diff bushings (not the subframe bushings) and look into getting a stronger bolt (one that's not fully threaded).

IFX · 03-23-2012, 05:29 PM

Quote:

Originally Posted by Kyoshi71

When I did my exhaust I never removed the diff bolt (mainly because it's unnecessary). However, removal and re-installing of those bolts is not the primary cause of this problem. Think about it: There's no alignment issue; there's no pre-loading issue; there's no disposable parts issue, i.e. crush collars. The only thing one would think is the problem is the torque spec, which in my opinion is highly unlikely because they are mountd via rubber bushings. It does effect many more 6MTs than DCTs and wheel-hops have been a known cause of the failure.

It's been said before that it's probably a combo of inadequate bushings, which allow the diff too much travel, coupled with inadequate tensile strength of the bolts.

Change the diff and sub-frame bushings - problem solved.

I don't understand, people are paying north of 70k for these cars... Why should they have to change the diff and sub-frame bushings?

It should be fine for hard daily driving, if you're trying to drag the M, well then I would understand.

Kyoshi71 · 03-23-2012, 06:15 PM

Quote:

Originally Posted by IFX

I don't understand, people are paying north of 70k for these cars... Why should they have to change the diff and sub-frame bushings?

It should be fine for hard daily driving, if you're trying to drag the M, well then I would understand.

I couldn't agree more.

Rshane · 03-24-2012, 03:10 AM

It's been proven the that by dropping the exhaust by unbolting the hangar from the diff does not have anything to do with these failures.

Most likely cause is shear forces these bolts experience during wheel hop.

Rshane · 03-24-2012, 03:11 AM

Quote:

Originally Posted by IFX

I don't understand, people are paying north of 70k for these cars... Why should they have to change the diff and sub-frame bushings?

It should be fine for hard daily driving, if you're trying to drag the M, well then I would understand.

midlifecrisis · 03-24-2012, 04:42 AM

I'd be careful about trying to find a stronger diff bolt. It's probably better to break the bolt than something it's attached to. It may be the weak point in the system for a reason.

Grail05 · 03-24-2012, 10:31 AM

Quote:

Originally Posted by Rshane

It's been proven the that by dropping the exhaust by unbolting the hangar from the diff does not have anything to do with these failures.

Most likely cause is shear forces these bolts experience during wheel hop.

Proven? I dont know bro, u have the proof? Its funny i say cause all the thread started about diff failure is when after they installedthe exhaust by themselve or dealer....

For those who had oem exhaust that was never removed had no issue well not that ive seen here anywyas....

Rshane · 03-24-2012, 10:38 AM

Quote:

Originally Posted by Sean05

Proven? I dont know bro, u have the proof? Its funny i say cause all the thread started about diff failure is when after they installedthe exhaust by themselve or dealer....

For those who had oem exhaust that was never removed had no issue well not that ive seen here anywyas....

This post explains it fairly well.

http://www.m3post.com/forums/showthr...7#post10779007

A theory i have is that folks who install aftermarket exhausts tend to beat on their cars a bit after the install just to hear the exhaust. They may do a couple of hard launches to hear the exhaust roar, experience some wheel hop, shear a couple of bolts, then assume the exhaust install may have something to do with it.

Bottom line, lots of conclusions based on assumptions instead of facts.

View Poll Results: Have you had your differential bolt break and replaced under warranty?
Yes, everything replaced under warrenty.	10	50.00%
Yes, BMW denied coverage because they say I "abused it"	10	50.00%
Voters: 20. You may not vote on this poll

03-22-2012, 08:57 PM	#1
F82_SID Brigadier General 255 Rep 3,150 Posts Drives: 2020 M2C 6mt HK Silver Join Date: Jan 2008 Location: Denver, CO. USA iTrader: (2)	Broken diff bolt poll Hey there, we have been seeing so many differential bolts breaking lately that I just wanted to create a little poll to see what the degree of this problem is. __________________ 2011/E92/M3/MR/BB/ZCV/ZP2/EDC/2MT
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03-22-2012, 09:23 PM	#2
Shmelgy B.E. 457 Rep 764 Posts Drives: F80 M3 & 1969 Mustang Fastback Join Date: May 2010 Location: City of Angels iTrader: (3)	Bullshit, had to pay $250 and get it fixed __________________ Current: 2022 TRX & 2010 GT3RS Past: 2016 M3 Individual Grigio Telesto Pearl, Sakhir Orange/Black Full Leather w/ CF trim, 6MT, ZCP, CCB, etc... Previous: 2011 E92 M3 Melbourne Red on Black 6MT ZCP. --> now 2010 dedicated track car
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03-22-2012, 09:51 PM	#3
THE TECH BimmerPost Supporting Vendor 363 Rep 12,980 Posts Drives: BPMsport 2012 E92 M3 Join Date: Jun 2011 Location: Kansas iTrader: (45) Garage List 2013 Nissan GTR [0.00] 2019 Sierra Denali ... [0.00] 1999 Nissan Silvia [0.00] 1999 Nissan Skyline ... [0.00] 1998 Toyota Supra [0.00]	I'd like to know what's causing it.
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03-23-2012, 08:27 AM	#6
Kyoshi71 Colonel 118 Rep 2,528 Posts Drives: 2010 M3 Coupe Join Date: Jul 2006 Location: New York iTrader: (0)	When I did my exhaust I never removed the diff bolt (mainly because it's unnecessary). However, removal and re-installing of those bolts is not the primary cause of this problem. Think about it: There's no alignment issue; there's no pre-loading issue; there's no disposable parts issue, i.e. crush collars. The only thing one would think is the problem is the torque spec, which in my opinion is highly unlikely because they are mountd via rubber bushings. It does effect many more 6MTs than DCTs and wheel-hops have been a known cause of the failure. It's been said before that it's probably a combo of inadequate bushings, which allow the diff too much travel, coupled with inadequate tensile strength of the bolts. Change the diff and sub-frame bushings - problem solved. __________________ "But resist we much; we must; and we will much; about that be committed." ~Rev. Al Sharpton 2010 E92 M3\|Silverstone II\|M-DCT\|NCSW\|2MT\|ZCW\|ZPP\|ZTP\|302\|507\|Gas Guzzler Tax
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03-23-2012, 08:37 AM	#7
Boostin FD Bored all the time 420 Rep 2,188 Posts Drives: Batmobile Join Date: Jan 2010 Location: Kirkwood iTrader: (2)	Which bolt are you guys talking about? I did my exhaust myself... and i never took any differential bolts off. __________________ Current: 2014 991 Turbo RS Past: 15 GT3, 17 R8 SC, Two 16 M4 GTS’s, Two 18 GT350R's, Two 13 RS5’s, 13 M3, 10 R8, 15 M4, 09 M3, 04 M3, 09 S5, 02 M3... It all started with an RX-7 (FD).
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03-23-2012, 09:09 AM	#8
DARK_M3 Banned 129 Rep 1,289 Posts Drives: 08 E90, 89 Grand Wagoneer Join Date: Mar 2012 Location: So Cal iTrader: (3)	Where's the "no" option in the poll?
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03-23-2012, 01:00 PM	#11
Boostin FD Bored all the time 420 Rep 2,188 Posts Drives: Batmobile Join Date: Jan 2010 Location: Kirkwood iTrader: (2)	the one all the way in the back... You can see them through the rear bumper. __________________ Current: 2014 991 Turbo RS Past: 15 GT3, 17 R8 SC, Two 16 M4 GTS’s, Two 18 GT350R's, Two 13 RS5’s, 13 M3, 10 R8, 15 M4, 09 M3, 04 M3, 09 S5, 02 M3... It all started with an RX-7 (FD).
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03-23-2012, 01:09 PM	#12
1MOREMOD - 11898 Rep 23,185 Posts Drives: Race car-> Join Date: Mar 2009 Location: check your mirrors iTrader: (5)	no i havent and have spent time screwing around on a skid pad as well as lots of track abuse. i get under there and check periodically if the are tightened up. __________________ 02 Tiag e46 M3\|6MT\|GC plates\|MCS c.o.\|GC bars\|GC race control arms\|GC bushings\|BW eng. & tran. mounts\|subframe kit\|BW race shifter\|BW Jaffster\|Euro header\|BW exhaust\|K&N c.a.i.\|Epic race tune\|Rouge pulleys\|Seibon CF hood\|CSL bumper\|apr gt 250 & splitter\|ST-40\|XR-2\|SS lines\|half cage\|Recaro profi\|Profi 2 harness\|BMWpedals\|BW studs\|
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03-23-2012, 01:30 PM	#14
saeedg48 Brigadier General 397 Rep 3,571 Posts Drives: Porsche 991.1 GT3 Join Date: Nov 2008 Location: Newport Beach, CA iTrader: (1)	anyone have pics?! __________________ 2015 Porsche 991.1 GT3 2015 F80 M3 -- Individual; Space Grey
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03-23-2012, 05:17 PM	#15
M3PO Colonel 99 Rep 2,792 Posts Drives: '08 IB E92 Join Date: Sep 2011 Location: OC iTrader: (7)	This is kinda scaring me. I think i may upgrade the diff bushings (not the subframe bushings) and look into getting a stronger bolt (one that's not fully threaded).
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03-24-2012, 03:10 AM	#18
Rshane M-Flight Member 40 Rep 1,085 Posts Drives: 2011 E92 M3 Join Date: Jul 2010 Location: San Antonio, Texas iTrader: (0)	It's been proven the that by dropping the exhaust by unbolting the hangar from the diff does not have anything to do with these failures. Most likely cause is shear forces these bolts experience during wheel hop. __________________ 2011 Le Mans Blue M3// Black extended Novillo w/ Blue Grey Aluminum trim/DCT/ZTP/ZCW/ZPP/ZCP Premium Sound ///Akrapovic Evolution Exhaust 2015 Audi S4 Prestige, Brilliant Black S-tronic 2012 Le Mans Blue 135i M Pkg DCT
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03-24-2012, 04:42 AM	#20
midlifecrisis Major 971 Rep 1,269 Posts Drives: 2017 X5 35d, 2019 230i X Join Date: Mar 2008 Location: New Jersey iTrader: (0)	I'd be careful about trying to find a stronger diff bolt. It's probably better to break the bolt than something it's attached to. It may be the weak point in the system for a reason. __________________ 2017 X5 35d (Performance Center delivery March 2017) 2019 230i X-drive 2022 M3 base 2000 328i sedan (UUC suspension - still the favorite), 2006 M3 slick top - Alpine White/Cinnamon SOLD! 2008 E90 M3 SOLD! 1991 325iX (both great), 2019 Miata RF - various others not as memorable but gone.
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