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Discussion Starter #1
the presure plate with a stage II SPEC, the clutch feels great but it will not disengage fully...foot all the way down and it's very hard almost impossible to put in gear. mechanic says it's the pressure plate ANY IDEAS? :confused:
 

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The first thing to check is that there is no air in the clutch master/slave cylinder circuit. This can happen if the slave cylinder hose is disconnected (not necessary to pull the trans). A simple bleeding will usually work. Sometimes the slave cyl. needs to be removed, turned so the bleed port is "up", and a clamp put on the pushrod and compressed. If this doesn't fix the problem, try to drive the car a few hundred miles of stop-and-go driving to get the "fuzz" off the disk (i.e., break in the clutch). The third possibility involves the self-adjusting feature. It is my understanding that Spec uses the factory BMW pressure plate as a starting point, including the problematic plastic self-adjusting ratchet. This may not be adjusted properly (i.e., too far "advanced"), as if the disk were thinner than it is. This can't be reset without pulling the pressure plate and using the BMW tools (the design of the self-adjusting mechanism is such that it can only self-adjust as wear occurs - the disk gets thinner).

If all the above doesn't work, either there is an incipient failure of the master or slave cylinder, or the pressure plate was built with too much leverage (too little clamp plate displacement for the available pedal throw). This seems unlikely as Spec has been doing this for a while, but is sometimes a problem with modified pressure plates.

Good luck

Regards, Dick Roberts
 

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Wow! you are #2 out of 2 people who installed a SPEC clutch and complained of drivability after the install. Maybe it's not ain install issue. The first guy who installed a SPEC clutch on his M5 ended up trading in for a X5. This is not good.
 

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dmz said:
Wow! you are #2 out of 2 people who installed a SPEC clutch and complained of drivability after the install. Maybe it's not ain install issue. The first guy who installed a SPEC clutch on his M5 ended up trading in for a X5. This is not good.
At some point, a trend develops......

Do NOT drive the car with this dragging clutch symptom. The transmission is having difficulty because it's tiny synchros are incapable of stopping the "dragging" clutch disc. They will very quickly overheat and warp. If you repeat this tranny shifting exercise many times, you can add a $5K tranny to your shopping list. The synchros are not sold separately and nobody can rebuild your tranny except Getrag under an exchange core basis.
 

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Discussion Starter #5
the pressure plate according to Spec has the SAC feature disabled, i'm going to try bleeding the system...i'll let ya'll know what happens
 

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I think my several posts on the dangers of SAC ("disabled" or not) should be made a "sticky" as a service to all E39 owners.

Sounds like you are definitely having a SAC issue. Due to the design of that mechanism, even SPEC's technique of "locking" the mechanism is not always effective.

Why did you get the Stage2? The kevlar disk (I won't say "I told you so" until the moderators make this info a "sticky" here on M5board) is completely inappropriate for applications that see significant drag... such as a heavy M5 with lots of torque in daily-driving situations. The link that I have posted a few times as a guideline for choosing clutch materials:

http://www.uucmotorwerks.com/CLUTCH/

I would never use a kevlar disk in anything other than a lightweight road-racing car. It has no benefit for a street car, and will be very easy to permanently cook. With the incomplete release situation you are experiencing, you may have already glazed the disk.

This is the info about SAC that I have posted before (moderators - sticky?):

Many E39 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 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. Hard use, even within normal usage parameters, can cause the self-adjuster to slip.
 

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Discussion Starter #7
the guy's @ SPEC are sending me out another clutch kit, lets see if this one works out...if the original kit turns out to be defective should i pursue reimbursment for my mechanics labor? :confused:
 

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m5jmh said:
the guy's @ SPEC are sending me out another clutch kit, lets see if this one works out...if the original kit turns out to be defective should i pursue reimbursment for my mechanics labor? :confused:
Why not insist on a full parts refund and cut your losses? Isn't this a fool me once scenerio? Shame on somebody...

This could be an 0 for 3 exercise for this particular M5 Spec Clutch assy. A "disabled SAC" design sounds super lame to me. Is that something you want? Are you willing to absorb labor fees & inconvenience for two failed experiments?? Are you aware that another fellow had the same misfortune? It sounds to me like their "defeated SAC" setup is overadjusted or underadjusted when shipped & they don't quite know what they're doing. The contraption that BMW uses to adjust a SAC from initial settings is real complex. They used to do this when mixing new and used parts, but they later learned to use all new.
 

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How many miles did you put on this clutch? Any track days? Did you not look a the UUC option? Just curious as one day many of us will cross this same path.

Good luck. I agree with the comment above, time is money so getting the best working solution next time might make you feel better about it.
DMC
 

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Discussion Starter #10
original clutch lasted 62K, the SPEC unit had o miles, never made it out of the workshop, i am going to try them one more time. i don't track or drive excessively hard so i thought this unit would be ok...this time i'm going to install it myself..i'll let keep y a'll posted


happy ///Mdays :2:
Jose
 

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Jose,

I am also thinking about the SPEC clutch and light weight flywheel to replace my stock setup. Did you also buy their flywheel? I will be curious to see how it all pans out. Thanks.

Mike

m5jmh said:
original clutch lasted 62K, the SPEC unit had o miles, never made it out of the workshop, i am going to try them one more time. i don't track or drive excessively hard so i thought this unit would be ok...this time i'm going to install it myself..i'll let keep y a'll posted


happy ///Mdays :2:
Jose
 

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mikeoski said:
Jose,

I am also thinking about the SPEC clutch and light weight flywheel to replace my stock setup. Did you also buy their flywheel? I will be curious to see how it all pans out. Thanks.

Mike
Have you done any searches, Mike? This little 9-5/8" Spec clutch seemingly has nothing to offer. From what I can tell, it is the flimsy, undersized OEM BMW/LUK pressure plate with it's stupid SAC gizmo defeated via some inconsistent bandaid approach. This particular clutch kit has a 0 for 2 record. It chronically slipped in the customer #1 car and it did not properly disengage in the customer #2 car. Customer #1 spent $50K replacing his Spec Clutch with a new X5 and Customer #2 car is still out-of-service. A lightweight flywheel combined with a small diameter 9-5/8" clutch will rattle because it has the lowest inertia. This setup is unreliable, weak and noisy. Kits with the most roller noise will generally have a small 9-5/8" clutch combined with a lightweight flywheel.

Just trying to help.
 

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I have been wrestling with 3 options.

1. UUC 850 CSI Clutch and LTW Flywheel
2. SPEC Clutch Stage 1 or 2 and LTW Flywheel
3. Dinan LTW flywheel and OEM clutch

Or just put the newer OEM clutch vs. the '00 one currently in my car.

I am building up the power in the car via Dinan mods. Stage 3 now, diff goes in next week and headers in Feb '05 which the throttle bodies and velocity stacks to follow later in '05. My shop has informed me that the '00 clutch will not harness the increased torque/hp and that the time to make the swap is when the headers go in.

I have not found any other options and am always open to hear what the rest of the M5 community has experience with.

Mike

Lscman said:
Have you done any searches, Mike? This little 9-5/8" Spec clutch seemingly has nothing to offer. From what I can tell, it is the flimsy, undersized OEM BMW/LUK pressure plate with it's stupid SAC gizmo defeated via some inconsistent bandaid approach. This particular clutch kit has a 0 for 2 record. It chronically slipped in the customer #1 car and it did not properly disengage in the customer #2 car. Customer #1 spent $50K replacing his Spec Clutch with a new X5 and Customer #2 car is still out-of-service. A lightweight flywheel combined with a small diameter 9-5/8" clutch will rattle because it has the lowest inertia. This setup is unreliable, weak and noisy. Kits with the most roller noise will generally have a small 9-5/8" clutch combined with a lightweight flywheel.

Just trying to help.
 

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Sounds like you need option #1!



mikeoski said:
I have been wrestling with 3 options.

1. UUC 850 CSI Clutch and LTW Flywheel
2. SPEC Clutch Stage 1 or 2 and LTW Flywheel
3. Dinan LTW flywheel and OEM clutch

Or just put the newer OEM clutch vs. the '00 one currently in my car.

I am building up the power in the car via Dinan mods. Stage 3 now, diff goes in next week and headers in Feb '05 which the throttle bodies and velocity stacks to follow later in '05. My shop has informed me that the '00 clutch will not harness the increased torque/hp and that the time to make the swap is when the headers go in.

I have not found any other options and am always open to hear what the rest of the M5 community has experience with.

Mike
 

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I maybe wrong. It was my understanding, that the pressure plate was the weak point in our cars. Along with the small sized clutch. If SPEC offers their clutch with a stronger pressure plate, that would seem to help the problem alot. A few people have been lucky with their original clutches, including me w/ 70K miles. What is SPEC's backgroud? Seems like a decent company, but nobody's had any luck yet.
 

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alibo70 said:
I maybe wrong. It was my understanding, that the pressure plate was the weak point in our cars. Along with the small sized clutch. If SPEC offers their clutch with a stronger pressure plate, that would seem to help the problem alot. A few people have been lucky with their original clutches, including me w/ 70K miles. What is SPEC's backgroud? Seems like a decent company, but nobody's had any luck yet.
Clamping force of the pressure plate is only a minor part of the "problem." Even with a much larger clamping force, you are still forced to transmit power through the meager 9 5/8" clutch disc = big time heat generation. During all out launches, hard shifts, track use, etc., any time significant power is attempted to be put through this small clutch disc, the disc temperature soars. Due to its small swept area it generates very high temperatures right away resulting in degeneration of the clutch disc material. Repeated use in these conditions can waste the disc in short order. The main "cure" for this situation is a disc with a larger swept area and therefore larger thermal capacity.
 

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mikeoski said:
I have been wrestling with 3 options.

1. UUC 850 CSI Clutch and LTW Flywheel
2. SPEC Clutch Stage 1 or 2 and LTW Flywheel
3. Dinan LTW flywheel and OEM clutch

Or just put the newer OEM clutch vs. the '00 one currently in my car.

I am building up the power in the car via Dinan mods. Stage 3 now, diff goes in next week and headers in Feb '05 which the throttle bodies and velocity stacks to follow later in '05. My shop has informed me that the '00 clutch will not harness the increased torque/hp and that the time to make the swap is when the headers go in.

I have not found any other options and am always open to hear what the rest of the M5 community has experience with.

Mike
The only other person who has had luck in the US with a non UUC clutch for higher horsepower applications is RRoberts. His clutch is based on the OEM, but he makes some modifications. He might chime in if he sees this thread, or you can try PM'ing him.
Regards,
Jerry
 

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I have been busy with work lately and do not get to read as much as I used too, but I was at one time convinced that the UUC clutch was the way to go and had not heard much about other set ups, I was planning on getting a UUC set up when I replace my clutch, and I am just wondering why everybody doesnt use the proven set up or have I been mis lead?
 

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bmwusa said:
I have been busy with work lately and do not get to read as much as I used too, but I was at one time convinced that the UUC clutch was the way to go and had not heard much about other set ups, I was planning on getting a UUC set up when I replace my clutch, and I am just wondering why everybody doesnt use the proven set up or have I been mis lead?
Although the UUC is initially $$$, it is designed to last a long time and parts are easily sourced through BMW suppliers or the dealer. In the long run, I have become convinced it is a relative bargain. The only negative I have ever seen about the set up is the rollover noise (gear lash) in neutral with the clutch not depressed. It is different for each car and each persons tolerance. RRoberts takes a stock unit and I believe machines about 2mm off of the pressure plate ( or flywheel, I can't remember) and I think uses an M3 clutch disk. He gets better clamping force, and he has been very happy with the setup from his postings.
If noise is not an issue for you, then I believe the board consensus is that the UUC setup is the best readily commercially available unit, and Rob @ UUC is incredible with his level of service. Just IMHO.
Regards,
Jerry
 

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alibo70 said:
I maybe wrong. It was my understanding, that the pressure plate was the weak point in our cars. Along with the small sized clutch. If SPEC offers their clutch with a stronger pressure plate, that would seem to help the problem alot. A few people have been lucky with their original clutches, including me w/ 70K miles. What is SPEC's backgroud? Seems like a decent company, but nobody's had any luck yet.
Spec has the same problems as other companies that try to cover a broad number of cars from A to Z. They produce some excellent clutches for certain applications, but in other cases, they are re-boxing other folks products. If you buy Sachs SAC for E39, you get a Luk pressure plate. The exact same situation exists for the popular Centerforce company. They rebox LUK for Corvette applications because LUK is the only mfr of a C4 Corvette pressure plate. You can pay $275 to $600 for a kit containing the same exact pressure plate from a half dozen mfrs, including GM. Some of them are repainting and restickering.

The M5 OEM weakness involves two points...insufficient swept area & SAC autoadjust failure.

Increased clamping pressure will NOT improve longevity of an undersized clutch during periods of intentional, extended slip. If you slip a clutch near WOT to prevent wheelspin, it must be large enough to absorb gobs of energy without seeing excessive temps. An overworked clutch will cook, just like a tiny brake system. Elevated pressure plate force offers the same effect as pushing on your brake pedal harder when the brakes are overheating and fading. It does not address root cause...too small.

This is presisely why Ford and GM switched to larger clutches after progressively elevating pressure plate clamping forces year after year. A 10" single disk clutch with streetable disk compounds is only good for around 300 lb-ft of torque, no matter what pressure plate clamping forces are used. Installing a modest clutch with a monster clamping spring that forces the driver to dump the clutch (to minimize heat rise) is impractical for street. BMW should have followed everyone else's lead. A 400HP sports motor deserves a clutch that's strong enough for a $20K 3/4 ton pickup truck. Most all HD pickup trucks have clutches in the 11" range. Such diameters allow tremendous heat absorption with good modulation & extended life.

It's my understanding that the SPEC M5 9-5/8" pressure plate is sourced from LUK. This would support the premise that all pressure plates designed to fit the E39 BMW SAC setup with dual mass are made by LUK and therefore exhibit the same weaknesses. It should not matter if the kit has Sachs or Spec's name on the box. You're getting a tiny clutch with "issues". It appears that Spec has introduced some new issues of their own upon defeating the SAC mechanism on their 9-5/8" kit.
 
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