Catastrophic Clutch Disk Failure... Need Opinions!

[bigjae1976]

Mine wasn't nearly as bad. I think the bolt fell out as I stopped the car. Because it drove OK although I did notice that it was shifting a little weird. Parked it. And then the clutch wouldn't disengage at all. Popped 2 slave cylinders before I dropped the tranny. Then the rear main seal was leaking...replaced that as well.

[jbrannon7]

Yes, you can clearly see the bolts were shaving the rivet heads, then the disc just gets ripped apart.

[robgoesvroom]

my UUC flywheel only came with 7/8 bolts. I purchased it for my S52 E30 back on Black Friday 2013 and forgot to check the quantity of bolts. I never opened the package until this past May. Did the install on a Sunday and was quite frustrated. Didn't bother to call UUC and wait for them to ship one bolt. Found out the E30 front caliper bolts are the same! Now I am worried about this happening to me too.

[robgoesvroom]

Did all of you people who had failures switch to a different flywheel setup?

[99MPower]

its not a scaling issue. I've NEVER seen another manufacture of a flywheel have any issue like what "we" see with these flywheels, on more than one occasion

[badmonkey]

Did all of you people who had failures switch to a different flywheel setup?

Yes, no issues with other setup.

its not a scaling issue. I've NEVER seen another manufacture of a flywheel have any issue like what "we" see with these flywheels, on more than one occasion

This

[Joshh]

my UUC flywheel only came with 7/8 bolts. I purchased it for my S52 E30 back on Black Friday 2013 and forgot to check the quantity of bolts. I never opened the package until this past May. Did the install on a Sunday and was quite frustrated. Didn't bother to call UUC and wait for them to ship one bolt. Found out the E30 front caliper bolts are the same! Now I am worried about this happening to me too.

I do not have a UUC flywheel but the bolts I was sent were a bit sort. By short I mean there were still more threads the bolts could thread into on the crank. I went to a local hardware store and purchased new 10.9 bolts that thread in as far as possible. I think they were another 1/4" longer.
After all the stories, I was going to do everything possible to prevent failure.

[bigjae1976]

its not a scaling issue. I've NEVER seen another manufacture of a flywheel have any issue like what "we" see with these flywheels, on more than one occasion

True. Never heard of this except with UUC LTW flywheels.

[Rob Levinson]

its not a scaling issue. I've NEVER seen another manufacture of a flywheel have any issue like what "we" see with these flywheels, on more than one occasion

Then you're not looking.

When this was a prevalent event due to a particular manufacturer's cam setup, the remarks about other brands were coming in exactly the percentage we would have expected.

And given the reports from our distributors who sold those other brands as well, they were indeed confirming that it was all brands.

Also, for those reading, consider the source - is the person making claims such as this one producing a competitive product, or is that person a known "hater" of a specific brand? Hmmmm...

[Butters Stoch]

Once you children learn how to install a clutch, then learn how to properly break in a clutch, threads like this will not exist.

That said, I've blown up, 1 stock, 2 clutchnet red clutches, 2 UUC M5 clutches and now on my 3rd disc with my clutchmasters FX725 twin.

[ScotcH]

Once you children learn how to install a clutch, then learn how to properly break in a clutch, threads like this will not exist.

That said, I've blown up, 1 stock, 2 clutchnet red clutches, 2 UUC M5 clutches and now on my 3rd disc with my clutchmasters FX725 twin.

Agreed ... I'd like to know how you guys attribute the failure to a particular manufacturer (besides anecdotal evidence of course ....)?

[bigjae1976]

I've never seen this with a JB racing flywheel which is a widely purchased model as well.

I'm guessing here...but with the known harmonic issue on M/S5X engines except for the S54 and the fact that the UUC flywheel is the lightest one that I know of...this leads to the bolts backing out.

Found out the hard way but on an M54B30, LTW flywheel and\or ATI damper = bad idea.

[ScottL]

One more step to add to the clutch install list: assemble pressure plate, disk, and flywheel on a bench, deliver to machine shop for balancing. Mark the plate and flywheel alignment before disassembly, then install.

I was surprised at how much material the shop removed from the plate housing.

[ScotcH]

I've never seen this with a JB racing flywheel which is a widely purchased model as well.

I'm guessing here...but with the known harmonic issue on M/S5X engines except for the S54 and the fact that the UUC flywheel is the lightest one that I know of...this leads to the bolts backing out.

Found out the hard way but on an M54B30, LTW flywheel and\or ATI damper = bad idea.

I run an M54B30, ATI damper, and a 12lbs flywheel clutch combo (tilton 5.5" twin disc). We also rev to 8000 rpm.

[bigjae1976]

I run an M54B30, ATI damper, and an 12lbs flywheel clutch combo (tilton 5.5" win disc). We also rev to 8000 rpm.

No forgot to add in the supercharger. That didn't quite work out too well.

[Mad Dog 20/20]

Blue flywheel curse

This.

[hide1]

its not a scaling issue. I've NEVER seen another manufacture of a flywheel have any issue like what "we" see with these flywheels, on more than one occasion

This. .

One more step to add to the clutch install list: assemble pressure plate, disk, and flywheel on a bench, deliver to machine shop for balancing. Mark the plate and flywheel alignment before disassembly, then install.

I was surprised at how much material the shop removed from the plate housing.

..And this.

See question #3 on Fidanza FAQ. (Fidanza makes the flywheel UUC rebadges) Although uuc states in their specs that the flywheel is tested at 11,000 rpm and spin-burst tested to 14,000 rpm, this is unfortunately, for the flywheel by itself. There are machine shops out there that will mark and balance the flywheel with pressure plate as an assembly for ~$50. Some argue this is overkill. It is absolutely nothing else but cheap insurance. I won't debate that other mfr's clutches have failed, but if you look at the uuc products, I cant believe how many of them are prefaced by engine lubrication failures including oil pump nuts, oil pumps, and crankwalk. As a mechanical engineer, I feel this points to a component that ads undue harmonics/ vibrations/ unbalances the rotating crank assembly. The crank and everything attached to it should be looked at as one balanced unit. This might be fine for you mother's camry but on our cars there will be issues. .

http://www.fidanza.com/faq.aspx
http://www.uucmotorwerks.com/flywheel/

Imo there is a bigger picture to why BMW chose to run a heavy dual mass flywheel on one end of the crank coupled with a non-viscous harmonic damper on the other. Either this motor had incurable harmonics and it was covered up with a lower redline and heavy DMF or they thought the heavy flywheel added a luxury feel and left off a viscous damper because the two weren't needed in unison (to value engineer). Whatever the case, a flywheel lighter than 9 lbs does not have the needed mass to dampen these harmonic issues. Even if they do tell you the coupling of the m5 pressure plate makes for the equivalent of 11.5 lb piece. I wont argue that on a bathroom scale that is true, however at 7,000 rpm is a different issue altogether.

It's too bad uuc doesn't still offer the old stage 1 package as I think it was a better compromise of performance and reliability, albeit heavier. Like it or not I have a feeling the stage 2 will be around for a long time. If you were to price out the components individually you could buy them all for a ~1/3 of the cost compared to msrp, which means they are very lucrative to sell. Not hating at all, just some constructive criticism, for the price, pre-balancing of the kits as a unit would be a great service.

[NeilM]

Interesting observations. Just one data point, but for the last M3 flywheel I installed (JB, I think) I had its new standard Sachs PP upgraded to double straps by Fort Wayne Clutch, then the assembly spin-balanced at 8K rpm. They reported that balance was perfect as-is and didn't even charge me for checking.

My own flywheel is a UUC with M5 friction disk and a Sachs Racing high clamping force PP. It was not checked for balance. It's been on my track car since 2005 and has done thousands of track miles with no issues at all.

OK, so that's two data points. ;-)

Neil

[Rob Levinson]

hide1, your objective engineering insight is appreciated.

However, there are some important details to consider:

It is known that the M5x-series engines (which covers all M50, M52, S50, S52) do indeed have a harmonic issue that happens around the low 7000rpm range. The damper is indeed there for a reason. To repeat the often-overlooked additional facts in the list of E36s that have had flywheel issues, the majority of these are with cars that are:

a) seeing track use with sustained high-rpm time
b) running aftermarket cams which change the harmonics
c) have software that raises the rev limit into this harmonic issue zone
d) sometimes have the harmonic damper removed (a bad idea no matter what flywheel)

And also not to overlook the fact that many of these engines, either due to age or hard use, are showing crank bearing wear that allows more free crank movement, which changes the dynamics of the harmonic and the rpm range affected.

Nevertheless, and this comes from dealing directly with BMW Motorsport engineers, it is the damper itself which is responsible for keeping this problem in check... the flywheel, when balanced, is a non-factor. Theoretically you could run the motor without a flywheel whatsoever. By the very fact that the same family of motors comes with different weight flywheels directly from BMW (including the automatic models which have only a basic drive plate), you can understand that changing the flywheel mass is not a factor as long as the harmonic damper is correct and all other factors above are considered.

Your reference to our older Stage 1 setup using the E36 clutch package is not heavier. As we explain on the Stage 2 product page, the total mass of the flywheel plus bolted-on clutch kit (which are considered one static unit at that point) is essentially identical.

The frustrating thing for people reading along with these threads and analyzing the situation is the repeated comments from those folks who, for either business loyalty or dislike, continue to perpetuate the myth that it "must be the product" without looking at all the other factors and the very important (and accurate) scaling issue. For any business discussed on Bimmerforums, the savvy forum reader will recognize that it's always the same few people that will bash them. There's a reason very few of the knowledgeable representatives from the advertisers will bother to get involved with discussions.

Cost-wise, of course there's a profit. Without being able to stay in business, no company would bother to manufacture parts. As for speculating on our margin, if our costs for 100% USA manufacturing were as low as you think, then we would have retired to our private islands a long time ago! The manufacturing, overhead, employee costs, etc., are significantly more than just the calculated component costs. The cheaper stuff you see for sale on ebay is invariably made overseas and absolutely does not have the quality control, reliability, or customer support that USA companies offer.

I do hope this clears a few things up and I welcome all rational and objective discussion.

[berny2435]

lol, so true! check out what happened when I tried to sell my blue flywheel

http://www.r3vlimited.com/board/show...&highlight=UUC

rivoted on, stamped parts. hmmm.
2 possible placed where defects could occur

posted here http://www.r3vlimited.com/board/show...5&postcount=13
it's mentioned that some bending

Originally Posted by Rob
Hi Eric,

I have an idea of what happened with this; what I can tell from that slight kink/bend on the drive straps is that the clutch appears to have been reverse-loaded... this means that a premature downshift caused engine braking to put power through the clutch assembly in the opposite direction. This causes the drive straps to be compressed and buckle, whereas normally they are in tension (pulled).

Regardless, I am willing to do a "goodwill" warranty replacement on the entire clutch for you.{snip}

https://www.flickr.com/photos/55094281@N03/6980304993/


I can't say what the failure mode was exactly, but as a manufacturing Engineer by trade, I can easily see many variables going on here with man, materials, and method, that can be causing issues with not only the parts, but the installation into the car (ref flywheel bolts)

I've seen multiple issues over the years with stamped parts and rivots. mix the two together and you can get a some high variances. Force some products together, preload some attachment points, break a single rivot, #$^& goes down hill. When specific rivot forming pressures are not met = variance. When a supplier sends you a batch of rivots that are a little harder than the first set, tooling is not changed for more force = variance. Softer rivots = variance. Worn dies to punch out plates = variance, dirty laser lenses = variance. Leaky machine hydraulics = variance. get my drift ? ;-)

The forces under braking are probably not fully understood. That first, large jolt, is nothing short of shocking, but probably less so than a drag launch. A good race driver, gets on the brakes hard and fast bc that's how its supposed to be done. There's tons of speed knocked off at the start of braking bc that's where the most grip is typically in the equation.

some say - You aint racing if you aint BREAKing something


I'm not here to defend UUC. I have no affiliation and own ZERO of their parts. I'm just merely pointing out a few things.. . I'm at 115K on my M3 on OE clutch and fly. This clutch decision isn't easy. Not looking forward to getting it done.

[NeilM]

rivoted on, stamped parts. hmmm.
2 possible placed where defects could occur

posted here http://www.r3vlimited.com/board/show...5&postcount=13
it's mentioned that some bending.

Relevance?

That thread describes an apparent pressure plate strap issue due to reverse loading, which in turn took out the clutch friction disk. The flywheel itself didn't seem to be involved. Strap failure is a known track/racing issue; its causes, and possible remedies, have been discussed here before. (See also my comment above about pressure plate strap reinforcement.). Virtually all aftermarket flywheels use pressure plates from Sachs or one of the other major suppliers.

Neil

[ross1]

I had this happen to me. Basically the flywheel bolt will catch the hub of the clutch disc and rip it all up.

Be aware that you should not put Loctite on the flywheel bolts for every BMW. I believe the S54 is one of them that do not get Loctite on the flywheel bolts.

This does make the most sense.
Those blaming it on a particular flywheel are just wrong. There is nothing about any particular flywheel that would cause the bolts to back out. Improper installation causes that, period.

[berny2435]

Relevance?

That thread describes an apparent pressure plate strap issue due to reverse loading, which in turn took out the clutch friction disk. The flywheel itself didn't seem to be involved. Strap failure is a known track/racing issue; its causes, and possible remedies, have been discussed here before. (See also my comment above about pressure plate strap reinforcement.). Virtually all aftermarket flywheels use pressure plates from Sachs or one of the other major suppliers.

Neil

start bending up clutches = variable that can cause vibrations = possible issues at the flywheel.

either way you slice it, lots of variables. I'm just pointing out that it's not allways company ABC's fault in design or quality of product. Installation error, wrong hardware used(bolts, locktite), user error, clutch from supplier had a defect (nothing to do with the flywheel)

[jbrannon7]

Relevance?

That thread describes an apparent pressure plate strap issue due to reverse loading, which in turn took out the clutch friction disk. The flywheel itself didn't seem to be involved. Strap failure is a known track/racing issue; its causes, and possible remedies, have been discussed here before. (See also my comment above about pressure plate strap reinforcement.). Virtually all aftermarket flywheels use pressure plates from Sachs or one of the other major suppliers.

Neil

Wrong, this clutch failed because the bolts backed out and sheared the rivets, then the straps failed.

[Mad Dog 20/20]

Did all of you people who had failures switch to a different flywheel setup?

Yes.