we have a NEW CLUTCH OPTION! - The Unofficial BMW M5 Messageboard (m5board.com)

dbox · 15th October 2004, 11:38

www.speclutches.com

i purchased a stage 3 with lightweight option and flywheel. it has been in my M5 for 3 days, and WOW what a difference! a friend that races mustangs told me about spec... he says he'd be very suprised if i could tear up this clutch with a 400hp car. so if anyone wants an upgraded clutch and doesn't want to spend UUC $ this might be for you(i paid $1500.00 for everything listed).

i'll keep everyone posted as i rack up the miles

. i finally feel i have a 400hp car

the dealer (yes, BMW) was so pleased with how my car turned out, they are now a SPEC vendor.

tampa_M5 · 15th October 2004, 15:04

that product looks very promising. Nice website, and good list of different style clutches. Good luck, and let us know how it works......i'll most likely use them as my next clutch, whenever that will be.

-Jonathan

SC'dKellenersM5 · 15th October 2004, 15:23

Wanna hear something even better...

SPEC Is the maker of the Flywheels and clutches for UUC...but they take the 850 csi size clutch and mate it to a new flywheel for UUC...not a standard size M5 disk.

The spec stg 4 is equiv of the UUC stg 3....

Lscman · 15th October 2004, 15:31

The best combo for street M5 is an organic disk combined with a big clutch.

1) aluminum flyheels are not for street use. A street car needs stored kinetic flywheel energy to launch smoothly and effortlessly at light throttle. A heavy street car with a light flywheel is the worst combo. An aluminum flywheel in an M5 will exhibit excessive rollover noise.

2) clutch diameter/swept area needs to be large for street use.
A small clutch may, in fact, hold up well in a race-only track car if a super high temp, grabby, whiplash-inducing ON-OFF clutch material is employed. The problem is...the resulting clutch behavior is not suitable for a tasteful 4dr street car. Street cars need a clutch that can be smoothly engaged while providing a couple seconds of low-throttle slip under certain parking/maneuvering conditions.

ELEVENS · 15th October 2004, 17:04

Quote:

Originally Posted by dbox

www.speclutches.com..i purchased a stage 3 with lightweight option and flywheel...

Very nice

Did you get the aluminum flywheel? Is it the stock diameter? How's the rollover noise? Is it "grabby" at all?

TCM · 15th October 2004, 17:07

Good post, I will definately keep this option in mind when my clutch finally goes (crossing my fingers right now, 40k and counting).

Rob Levinson · 15th October 2004, 17:15

We've been using SPEC as the manufacturer of our exotic-material clutch offerings for about two years now. In fact, we're a SPEC distributor and offer all fitments at a significant discount from SPEC's online price. It's no secret... our website and online order forms say "SPEC Stage (X)" in the options list.

While the SPEC Stage3/4 material may have greater capabilities than the same-size organic disc, the same abuse from an inadequate size still affects the longevity... and the smaller size is definitely more "grabby" than the larger size we use in the UUC V12 clutch conversion simply due to a smaller area of material being responsible for the complete engagement.

But in all reality, that's only half the story with the E39 M5 clutch problem... the other part of the equation is the problems with the pressure plate.

SPEC's OE-fitment clutches use "enhanced" pressure plates for more clamping force, the same OE plate you get in a new BMW clutch. What this means for M5 owners is that the SPEC E39 M5 pressure plate retains the Self Adjusting Clutch (SAC) mechanism. To quote from the explanation on our website:

Many E46 3-series and E39 5-series owners have experienced mushy clutch feel, inconsistent engagement, and premature wear of the clutch in their manual-transmission cars.* The reason is quite simple - the original BMW (LUK-manufactured) clutch in the E46 and E39 has a new "SAC" (Self Adjusting Clutch) design.* This new mechanism built into the clutch pressure plate is supposed to keep the clutch pedal engagement point the same as the clutch wears... but in all reality, it's a case of* "an answer to a question that nobody was asking." They have added a layer of complexity and feedback isolation, filling a need that didn't need filling - it is not too often that anybody notices that their clutch engagement point as moved 1/2" over 50K miles.

The SAC mechanism itself causes problems; it over- or under-adjusts the pressure plate and therefore causes the clutch to slip or burn out prematurely. They are also known to shift, causing the pressure plate release fingers to slip off the plate, keeping 1/3 of the pressure plate engaged at all times. Bottom line is that the only fix is a complete clutch job, and your dealer is likely to claim "driver abuse". We have seen it happen too many times.

The SAC mechanism may not give a clean release like a standard clutch. Instead of just two sets of springs, there is an adjuster mechanism that makes engagement feel mushy or slow.

The UUC M5/V12 clutch conversion eliminates the SAC mechanism and restores traditional clutch feel with predictable and crisp engagement.

It's no fault of SPEC that LUK designed this sort of mechanism... but it does mean that the SPEC product equipped with SAC still has the same flaws. All the same SAC-related problems that afflict your original E39 clutch afflict the SPEC clutch in the same fitment.

We've had limited luck with "locking" the SAC mechanism to disable it... but truth be told, that had only limited success. A hard shift, or a hard driveline lash shockload force, would still cause an "adjustment" - more accurately a "misadjustment" - and problems would arise. And no matter what is done to modify the SAC, the clutch feel is still that same disconnected, mushy feel.

An analogy to a different activity hampered by equipment is appropriate here, one could say driving a SAC-equipped clutch is like "taking a shower in a raincoat."

At this point, UUC refuses to sell any brand clutch with a SAC mechanism, regardless if the part comes from BMW or SPEC. The reliability/durability is simply not up to our standards.

We gladly offer SPEC products in the non-SAC fitments (and we can even provide a SPEC Stage1 organic disc as an option) as we do for the M5 and all of our other flywheel fitments.

Sonic M5 · 15th October 2004, 17:40

[quote=dbox]
i purchased a stage 3 with lightweight option and flywheel. it has been in my M5 for 3 days, and WOW what a difference!
QUOTE]

dbox,
Thank you, you have given us some hope and hope is a powerful antidote.

. I have a few questions:- 1. In terms of feel what is the difference between the stock clutch and the stage 3 clutch you installed? 2. For the normal driver who does not do track or drag racing but just simply want to know that he as a good clutch that can support the 400 hp the M5 bring is the stage 3 the ideal clutch? 3. Is there any empirical data that shows that the stage 3 is a better clutch than the stock clutch? Thanks in advance for your thoughts.

FAST 5 · 15th October 2004, 18:20

Quote:

Originally Posted by Lscman

The best combo for street M5 is an organic disk combined with a big clutch.

1) aluminum flyheels are not for street use. A street car needs stored kinetic flywheel energy to launch smoothly and effortlessly at light throttle. A heavy street car with a light flywheel is the worst combo. An aluminum flywheel in an M5 will exhibit excessive rollover noise.

2) clutch diameter/swept area needs to be large for street use.
A small clutch may, in fact, hold up well in a race-only track car if a super high temp, grabby, whiplash-inducing ON-OFF clutch material is employed. The problem is...the resulting clutch behavior is not suitable for a tasteful 4dr street car. Street cars need a clutch that can be smoothly engaged while providing a couple seconds of low-throttle slip under certain parking/maneuvering conditions.

Question for LSCMAN,
What are your thoughts on DINAN's lightened FlyWheel? Im more interested in your opinion on the Stage 1 Lightweight Flywheel (Dual-Mass) .
Thanks!
Robert

dbox · 15th October 2004, 19:05

Quote:

Originally Posted by ELEVENS

Very nice

Did you get the aluminum flywheel? Is it the stock diameter? How's the rollover noise? Is it "grabby" at all?

very grabby, i did get the flywheel...as far as i know its stock diameter. is rollover noise gear lash? if so, i do have it but its worth it to me to have the car drive the way it does now.

dbox · 15th October 2004, 19:10

[quote=Sonic M5]

Quote:

Originally Posted by dbox

i purchased a stage 3 with lightweight option and flywheel. it has been in my M5 for 3 days, and WOW what a difference!
QUOTE]

dbox,
Thank you, you have given us some hope and hope is a powerful antidote.

. I have a few questions:- 1. In terms of feel what is the difference between the stock clutch and the stage 3 clutch you installed? 2. For the normal driver who does not do track or drag racing but just simply want to know that he as a good clutch that can support the 400 hp the M5 bring is the stage 3 the ideal clutch? 3. Is there any empirical data that shows that the stage 3 is a better clutch than the stock clutch? Thanks in advance for your thoughts.

the pedal feel of the stock clutch was much harder than this one. the pedal is so soft it takes so