BMW M5 Forum and M6 Forums banner

1 - 19 of 19 Posts

·
Registered
Joined
·
41 Posts
Discussion Starter #1 (Edited)
Is the price trade off equal to the performance trade off? Comments / suggestions / feedback appreciated.
 

·
Registered
Joined
·
2,289 Posts
I think it is...i was one of the first people other than those that work at UUc to know about the clutch and I even knew that spec was making the clutches for UUC.

there is a thread soemwhere where Rob L from UUC even discusses this topic.
 

·
Registered
Joined
·
41 Posts
Discussion Starter #4
like the same exact product?
 

·
Registered
Joined
·
41 Posts
Discussion Starter #5
Is it a smart idea to go with either the Spec Stage IV or UUC Stage III with almost no mods? (Tired of the weak OEM clutch)
 

·
Registered
Joined
·
2,289 Posts
honestly you dont need a stgIII uuc for no mods....really.

StgI and stg II are more than capable to handle anything you can throw at them...my supercharged m5 project car only needs a stg III uuc (although i might even need something above that when its done).

Im not trying to tell you NOT to get the stg III but its designed for hard core power additions and does not have a real light touch to it, like the oem does, compared to the stgI and II. As both of them are rated up to 500ft-lbs and beyond (690 for the stg ii). The stg III is rated up to 900.

If you decide to go with the StgII...be warned, it has a very regimented break in procedure that MUST be followed 100% as the kevlar material in the disk needs to be set properly. If it is not followed properly you could experience premature clutch wear, clutch hot spots, slipping and all.
 

·
Registered
Joined
·
41 Posts
Discussion Starter #7
Thank you brother... appreciate the help once more..
 

·
Registered
Joined
·
444 Posts
I had the impression from one of Rob Levinson's earlier posts that, while the flywheel for the UUC big clutch kit, and the disc for Stage II and up kits, are manufactured by Spec, the kits that Spec itself sells for the E39 M5 retain the factory 9.6 in. clutch diameter and use a reworked LuK pressure plate. Is this not correct, and only UUC sells the 11.0 in. clutch kit, based on the stock BMW 850CSi pressure plate and disc (refaced by Spec for the higher stages)?

Regards, Dick Roberts
 

·
Registered
Joined
·
2,289 Posts
guys...

im not trying to persuade anyone to NOT get a stgIII or any of specs clutches..im just trying to put the info out there that I know. The StgIII UUC has a higher effort, on/off style engagement setup that is less daily driver friendly than that of the other Stages offered. There was a gentleman that did install the StgIII on his car though and he made mention that the effort was not that great but certainly increased over OEM. You (Fart) and King might want to search that post...it might be listed down at the bottom of this page under the "like discussion posts"
 

·
Vendor
Joined
·
619 Posts
Greco said:
If I'm not mistaken Spec Stage III = UUC Stage I, UUC Stage III is Spec Stage V.
No, not at all!

First of all, realize that the SPEC offering for the M5 is the OE 240mm size. The UUC flywheel/clutch kit is a conversion to the huge 280mm clutch from the V12 850CSi.

The difference is obvious:



For full details, see:
http://www.uucmotorwerks.com/flywheel/V8/index.htm

As for the actual clutch materials we offer, our online ordering system spells it out in no uncertain terms:

Basic: OE BMW 850CSi clutch (organic)

Advanced: Sachs Power Clutch for the 850CSi (performance organic)

Hyper (recommended only for supercharged cars or frequent drag racing): SPEC StageIII multi-puck carbon/semi-metallic for the 850CSi.

We can offer any of the SPEC materials, but we feel the options we present are better. The SPEC StageI is similar to the Sachs Power Clutch, but is more expensive. The SPEC StageII is a kevlar disk, which is not recommended for street driving due to the slip and heat tolerance characteristics. StageIII we offer. and StageIV and V are variants of that with some changes that adversely affect street use without any benefit.

The question was asked in another thread about the SPEC M5 offerings for the M5. This was my response:

----------------------------------------------
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.
----------------------------------------------
 
1 - 19 of 19 Posts
Top