Public Service Announcement: Watch your 6MT clutch! Carnage pics inside

[deansbimmer]

The 2008-2013 6MT clutches have been known to fail due to broken spring straps in the pressure plates. I have seen several of these now (old and new style clutches) where the straps break loose and damage the transmission case, but this is the first one I've seen where all the straps broke.

I'm dismantling this 2011 M3 with 64k miles due to a clutch fire. All of the spring straps broke which caused the clutch to lose stability and start slipping, generating heat. The straps also flung out into the trans case like a spinning cutting wheel which caused the case to break apart altogether. This resulted in enough heat to cause a clutch fire which spread enough to cause a total vehicle loss once the fire heated up the trans-tunnel and caught the interior on fire.

A clutch with some straps broken will still operate, perhaps with no signs of failure. One M3 I worked on had two stacks of broken spring straps but still drove, albeit with a very faint light clatter from the clutch area.

Cause of this failure is open to speculation. Perhaps too many harsh launches, too many burnouts, excessive clutch actuation (traffic), or just old age. Do think about the age of your clutch and consider servicing. Especially if you can hear abnormal noises from the area.

[SflBimmer8484]

Wow. Never seen that before.

[squartus]

Oh, I was trying to figure out what the cause of this was? Did not know what broke loose but it made a mess. Did not even know anything was wrong until I was replacing it with an aftermarket clutch.

[deansbimmer]

Originally Posted by squartus

Oh, I was trying to figure out what the cause of this was? Did not know what broke loose but it made a mess. Did not even know anything was wrong until I was replacing it with an aftermarket clutch.

Yeah. I think this happens more often than people think. Those straps disintegrate or come loose, sending shrapnel all about, or worse- as in the case of the car I'm dismantling now.

[jdamore]

I know this isn't the point but, doesn't the owner have insurance for fire damage?

Thanks for sharing! Thats low mileage!

[deansbimmer]

Originally Posted by jdamore

I know this isn't the point but, doesn't the owner have insurance for fire damage?

Thanks for sharing! Thats low mileage!

I'm sure he did, but cars with damage like this aren't repaired once they're totaled. The insurance company liquidates them and they usually get dismantled.

[bigjae1976]

Interesting. I've seen this on an E36 pressure plate from a ZF320 I bought. The strap was a pretty thin piece of steel which held the friction surface onto the outer plate. It was snapped off at the rivet.

Never seen a car burn down from a clutch fire though. Lucky me I have a DCT!

[PandaM3]

Wow never seen a car burn to the ground because of a clutch fire... is this a thing?

I figured the clutch would just start slipping then no longer function once worn...

If the clutch wears out and can cause a fire or shrapnel that can come through the trans tunnel... doesn't that warrant an nhtsa investigation?

[Solo_M_Tech]

I replaced a clutch in an 08 e92 last week that this happened too. i broke the reluctor wheel teeth on the flywheel and broke the crankshaft sensor. It also put 2 quarter sized holes in the bellhousing and scratched the shit out of the inside of the bellhousing. Made me aware of my 96k mile M3 and its assumed original clutch.

[Mvy]

Well I guess we know now why BMW upgraded the flywheel after 08 ;-)

[pbonsalb]

Originally Posted by Mvy

Well I guess we know now why BMW upgraded the flywheel after 08 ;-)

The OP wrote that the M3 that burned was a 2011. Maybe the heavier flywheel BMW installed after 08 to address complaints of audible gearbox noise transmission was not to prevent clutch destruction.

[Obi Wong Kenobi]

Now this makes me wary of the OEM application. Are aftermarket prone to this as well? If not, what clutches/flywheels are owners moving toward with success?

[deansbimmer]

Well you guys have confirmed that it's not just me, and that it's obvious that this has happened to a number of engines- both old and new style. I don't think that this is a big enough concern to cause everyone to rush out and pull their transmissions in a panic, and certainly not major enough for some crazy NHTSA investigation (lol), but owners should not assume that a clutch in such a high performance application should last 100k without even an inspection.

According to evidence in the case of this burned M3, I'm struck with the suspicion that its owner (who purchased this car from a buy-here, pay-here lot in NY) was the oblivious type who couldn't afford the car to begin with and ignored any signs of trouble either due to ignorance, or flat out neglect.

Anyone with any sense of awareness for their car would have noticed something wrong with their clutch before it caused a fire.

[squartus]

Originally Posted by Obi Wong Kenobi

Now this makes me wary of the OEM application. Are aftermarket prone to this as well? If not, what clutches/flywheels are owners moving toward with success?

I really like my spec performance clutch/flywheel, oem feel but does engage a little quicker. And can withstand far more abuse/power.

[Obi Wong Kenobi]

Originally Posted by squartus

I really like my spec performance clutch/flywheel, oem feel but does engage a little quicker. And can withstand far more abuse/power.

Yeah, I've been looking at the Spec clutches. Just started my search so looking for real owner experiences and what's out there. I believe MFactory has one coming out too. Thanks for the input!

[deansbimmer]

Spec is a great company. I haven't installed one personally in an E92 M3 but have driven a few (didn't care for them). I ran one in my 456whp e36M3 for 22k miles and it was still awesome when I sold the car, so clearly their feel depends on the platform.

[BPMSport]

Mine looked perfect when I replaced it at 50k with the newer 09+ clutch and flywheel.

That's pretty crazy...

Edit - sorry for 5 month later post.. iPhone app saved it as a draft and just posted it now for some reason?

[dkexige]

Thanks for sharing. Something for me to keep in mind.

[L4ces]

Originally Posted by Mike Benvo

Mine looked perfect when I replaced it at 50k with the newer 09+ clutch and flywheel.

That's pretty crazy...

Edit - sorry for 5 month later post.. iPhone app saved it as a draft and just posted it now for some reason?

Hi Mike. Did your have problems or was there something I missed that made you upgrade?

[BPMSport]

Originally Posted by L4ces

Hi Mike. Did your have problems or was there something I missed that made you upgrade?

No problems, but the newer version had a larger flywheel and clutch which was supposed to reduce chatter, so I just went for it.

[jeff@autocouture]

Wow haven't seen something like this, i would figure the clutch would melt/send fragments everywhere but not catch fire.

[thongvua]

Hi folks,

I just recognized something quite concerning while doing my rod bearings, mine was 6MT as well and I found loose pieces of shrapnel inside the mounting slots of the transmission bell housing. Please see the 2 red circles in my attached picture below, this was not my actual transmission housing pic since my focus was on the rod bearings at the time and thought this was just normal transmission wears until I found this thread. Beside shrapnel I found some sizable cubes of metal that stuck in both slots but were a bit too big to be pull out. I have no idea how they got into those slots, is this the same issue that deansbimmer was referring to?