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That's right, 2nd stock clutch is revving the motor in the 2 and 3 gear upshifts @ >4500 rpm. I know this is the weak link. but what are my upgrade options?? Thanksabunch, Bobby O.
 

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The 9-5/8" factory clutch is too small and the autoadjust mechanism is prone to failure. The V12-based 11" UUC clutch for M5 has 50% more surface area and it does not have a stupid autoadjust pressure plate mechanism.
 

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Beware that there are reports of some gear rattle noise with the UUC clutch, but to me, that's a small price compared to having to replace the clutch 2x in 42k miles. More importantly, the UUC clutch lets you drive the car the way it was meant to be driven.
 

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RennSportSC'dKellenersM5 said:
in addition to lscman's comments..the UUC also comes in three different levels of performance for differing customers.
You can read about the threee differant versions of the UUC products HERE

Please let us know if you have any further questions.

Thanks

Sean
 

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RRoberts also has posted a work up of the stock unit with some upgrades and machining of the flywheel IIRC. The downside is it is still a 9 5/8 inch clutch, the upside is no gear lash noise. If you don't drive hard, it might work for you. If you like to go hard from stoplight to stoplight, then UUC is the only choice.
Regards,
Jerry
 

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Fart said:
Dont mean to sound stupid, but the UCC kit is based on the V12, and becouse they use the same gearbox (6speed Getrag) it fits.

But is the original Sachs V12 clutch that different from factory, does it need heavy modding to fit the M5? I really dont want the lightweight flywheel.
The 8 series V12 engine Getrag gearbox is substantially sturdier than the Getrag Type 226 used in the 5 series E39. It is not simply an upgraded box with better materials...it's bigger. They are not the same design platform, for sure. Getrag sells several 6 speed automotive transmissions of varying torque capacities used by Pontiac, Toyota, BMW, Maserati and other's.

The Sachs/BMW V12 11" clutch assembly is much larger than the M5's 9-5/8", so a dual mass flywheel can not be employed. The 8 series could not use a dual mass flywheel like the 5 series, unless the bell housing was much larger. Such a design change would not fit in the stock transmission tunnel. An 8 series V12 flywheel will not work on a 5 series V8, if that's what you're considering.
 

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Fart said:
Dont mean to sound stupid, but the UCC kit is based on the V12, and becouse they use the same gearbox (6speed Getrag) it fits.

But is the original Sachs V12 clutch that different from factory, does it need heavy modding to fit the M5? I really dont want the lightweight flywheel.
I have been thinking the about this also.<O:p</O:p
Will the stock 850 Csi flywheel work in the M5 if not can it be machined to fit?
 

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Apex said:
I have been thinking the about this also.<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:eek:ffice:eek:ffice" /><o:p></o:p>

Will the stock 850 Csi flywheel work in the M5 if not can it be machined to fit?<o:p></o:p>

<o:p></o:p>
An 850 used single mass and it's tranny is very different. The NVH rollover issues may not be similar between the two cars.
 

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OK, I don't mean to hijack the thread, but the only objection to the UUC setup seems to be gear lash noise. After reading the UUC website, it seems the flywheel helps damp the power pulses that cause the noise. Would a non lightened, or "not so much" lightened flywheel help reduce the noise?
Regards,
Jerry
 

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Does anyone know if we can expect a Dinan clutch upgrade in the near future. Sure, it's more money, but I like the confidence I get when using Dinan labeled parts.

TexasM5
 

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Jerry:

There are numerous threads regarding the UUC setup, with some "complaints" about the gear noise with the clutch engaged, but not in gear. (Stopped at a light in nuetral). These have ranged from barely audible to a slight bit annoying, nothing that the radio can't fix. :biggrin: All comments I believe are with the windows rolled down.

I am going with the UUC Stage III setup, and I'd rather have a clutch I know can take whatever I dish out and accept some minor noise. Besides the Tubis will definately help if the radio breaks.

YMMV.
 

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jjc1843 said:
Jerry:

There are numerous threads regarding the UUC setup, with some "complaints" about the gear noise with the clutch engaged, but not in gear. (Stopped at a light in nuetral). These have ranged from barely audible to a slight bit annoying, nothing that the radio can't fix. :biggrin: All comments I believe are with the windows rolled down.

I am going with the UUC Stage III setup, and I'd rather have a clutch I know can take whatever I dish out and accept some minor noise. Besides the Tubis will definately help if the radio breaks.

YMMV.
Thanks Joe, I am aware of all that. I also followed the Royal Purple/No Royal Purple debate (which Rob says helps the noise), but based on Rick's concerns I would not go there. I am less inclined to put up with "some noise" in a high end luxury car; I don't mind on my dedicated track car. I don't do much street racing as the M5 is not a drag car; I don't abuse the clutch much at all. I find double clutch downshifting smooths out the downshift noticably. So the original question remains unanswered: can a heavier flywheel alleviate most or all of the noise? Maybe Rob will pick up on this and chime in. I think all of us realize we will be replacing clutchs on our own someday, so we might as well be prepared!!!! cherrsagai
Regards,
Jerry
 

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gsfent said:
.........can a heavier flywheel alleviate most or all of the noise?
Regards,
Jerry
I kinda tried to answer that one, Jerry. I doubt if anyone can produce a definitive answer:

1) An appropriately-sized clutch assembly (10.5" or larger) mandates single mass for bell housing fitment reasons.

2) Yes, it is safe to say a heavy steel aftermarket single mass would exhibit more rollover noise than a heavy OEM dual mass. A hefty single mass will not likely alleviate ALL the noise. Whether it would seem noticeably louder or annoying to somebody is anyone's guess. Be advised it's not just a flywheel weight issue. With single mass, the sprung disk design is a major factor in muting noise.

3) A hefty M5 flywheel compatible with a generously-sized clutch is not available, so guesstimation and supposition efforts seem moot.

4) Rollover noise (idling with clutch pedal out) for single mass combos can not be accurately predicted without actual road testing. Every combo has it's own NVH characteristics. In fact, transmission wear plus transmission & clutch tolerances may result in variations from car-to-car.

5) In summary, nobody can answer the question you posed for M5 because such parts are not manufactured or sold anywhere in the world.
 

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Lscman said:
I kinda tried to answer that one, Jerry. Not sure if anyone can produce a definitive answer:

1) An appropriately-sized clutch assembly (10.5" or larger) mandates single mass for bell housing fitment reasons.

2) Yes, a heavy steel aftermarket single mass would likely exhibit more rollover noise than a heavy OEM dual mass. A hefty single mass will not likely alleviate ALL the noise. Whether it would seem noticeably louder than OEM is anyone's guess.

3) A hefty M5 flywheel compatible with a generously-sized clutch is not available, so guesstimation and supposition efforts seem moot.

4) Rollover noise (idling with clutch pedal out) for single mass combos can not be accurately predicted without actual road testing. Every combo has it's own HVH characteristics. In fact, transmission wear plus transmission & clutch tolerances may result in variations from car-to-car.

5) In summary, nobody can answer the question you posed for M5 because such parts are not manufactured or sold anywhere in the world.
Thanks Rick. I asked the question because I understood the UUC flywheel was significantly lightened. So the thought occurred that if Rob took less weight off of the flywheel, would it help reduce/eliminate the rollover noise? Or, is there a way to tune out some of the noise on a car to car basis?? Royal Purple :nono: is not an option! :cheers:
Regards,
Jerry
 

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I hear the new Castrol-sourced LT2 suffix fluid is approved by BMW for Getrag.

Most UUC clutch buyers appear to be elated with their strong clutches and any rollover concern is secondary. Their comments seem to be in-line with aftermarket exhaust buyers willing to trade HP for a bit more noise (all the time). I have to wonder if there's enough demand out there for a wider selection of M5 flywheel designs.
 

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gsfent said:
Thanks Rick. I asked the question because I understood the UUC flywheel was significantly lightened. So the thought occurred that if Rob took less weight off of the flywheel, would it help reduce/eliminate the rollover noise?
The UUC flywheel/clutch assembly also has a larger "radius of gyration" which is the effective radius where the center of mass is located. It is the combination of radius of gyration + mass that yields the moment of inertia of the assembly. The stock system has more mass but a smaller radius of gyration. I tried to get Rob to give me a clear answer to what the moment of inertia of the two designs were, but I don't think the calculations have been fully done. Suffice it to say that the UUC setup would have to be lighter to just match the stock setup's moment of intertia (due to its larger diameter).
 

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gsfent said:
.......if Rob took less weight off of the flywheel, would it help reduce/eliminate the rollover noise? .........
Probably, but kinda like asking Borla to manufacture a separate line of 304 stainless exhaust systems with highly restrictive muffler baffling, hoping to maintain factory sound parameters. Same would go for CAI, superchargers, handling suspension or many other products that improve handling or acceleration. These products incrementally move your E39 away from it's 5er luxury car underpinnings.

Super duty clutch systems are invariably packaged with lighter flywheels to please performance enthusiasts who are trying to squeeze more performance out of their vehicle & this applies to all marques. The goal is to measurably improve throttle response, acceleration, speed-matching capabilities (for heel & toe) and ensure positive engagement with no extended slip under all conditions and duty. Realize that customers have been buying lightweight flywheels for their BMW's from Dinan and other's with small 9-5/8" clutches fitted. As CSBM5 mentioned, the oversized 11" clutch assembly moves the mass closer to the outer circumference of the rotating assembly which reduces rollover issues.

**It's interesting to note that rollover concerns are generally expressed by apprehensive "potential" customers with little or no first-hand knowledge, not 11" clutch kit owners. The owners generally rave about the big clutch kit capabilities while noting that rollover is seldom noticeable and totally manageable.
 
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