Sometimes, maybe once a week, my clutch acts weird. In 'normal' behavior, I can let go of the clutch pedal about an inch (maybe half an inch) before it engages (is this the correct word?). But sometimes, it immediately engages, and when the pedal is released completely, it is not at the same level as the brake pedal. I have to lift it up with my left foot. The next time I change gears, everything goes normal.
Sometimes, maybe once a week, my clutch acts weird. In 'normal' behavior, I can let go of the clutch pedal about an inch (maybe half an inch) before it engages (is this the correct word?). But sometimes, it immediately engages, and when the pedal is released completely, it is not at the same level as the brake pedal. I have to lift it up with my left foot. The next time I change gears, everything goes normal.
This is particulary annoying when parking...
Sounds like the notorious clutch pressure plate SAC (self-Adjusting Clutch) mechanism is failing. This will likely lead to slip and failure at an inopportune moment. Some aftermarket M5 clutches have the troublesome SAC deleted, including UUC (forum sponsor). They sell a 9-5/8" high performance clutch and a monster 11", optimally suited for 400 HP powerplants.
Another possibility is the pedal pivot bushing failing, but it's not likely to cause the engagement height to change that much.
I was planning on upgrading to the UUC clutch anyway, but only after this one goes.
What's the difference between the two UUC clutches? Is bigger always better? If I need to replace a part, and I have a choice between two options, I always tend to go to the biggest/strongest/best option. Is the 11" the best option for all purposes?
I was planning on upgrading to the UUC clutch anyway, but only after this one goes.
What's the difference between the two UUC clutches? Is bigger always better? If I need to replace a part, and I have a choice between two options, I always tend to go to the biggest/strongest/best option. Is the 11" the best option for all purposes?
The only downside of the larger clutch is that it's more expensive, and may have a bit more rollover noise. (due to replacement of dual mass flywheel). Take a look online at UUC. There is much detail regarding this. I don't have it yet, but I'm planning to purchase the 11" clutch within the next couple of weeks.
The only downside of the larger clutch is that it's more expensive, and may have a bit more rollover noise. (due to replacement of dual mass flywheel). Take a look online at UUC. There is much detail regarding this. I don't have it yet, but I'm planning to purchase the 11" clutch within the next couple of weeks.
If you have "chipped" your car, your tuner may be able to raise the idle speed a little to help reduce rollover noise. And Rob has just posted a price reduction on the UUC V12 clutch, so check out his webiste.
Regards,
Jerry
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I heard a lighter flywheel results in difficult idling, having to play the throttle to keep the engine running... Is this true?
Not exactly. There are several things to consider:
1) If you switch from dual mass flywheel to single mass, the total weight of clutch assembly plus flywheel will determine how much rollover noise you hear. A factory-sized BMW clutch is tiny & light, so it will make significant rollover noise when combined with a lightweight single mass flywheel. An oversized 11" clutch is massive and heavy in comparison, so it's rollover noise is much lower than other single mass lightweight flywheel setups.
2) You will not experience stalling at idle with a lightweight flywheel, unless your engine has problems. Folks with lightweight flywheels combined with tiny lightweight 9-5/8" clutches tend to hold the throttle simply to reduce rollover, when they are sitting at idle with tranny in neutral and clutch pedal out. Their cars are not stalling. The rollover noise is never present when the transmission is in a gear with the clutch pedal in OR out (1,2,3,4,5,6,R).
3) The UUC 11" clutch & flywheel setup is significantly heavier than ALL other single mass flywheel setups & this mutes rollover noise. For this reason, most folks do not consider the rollover of the biggie clutch setup to be an issue. The benefits of the 11" clutch (50% greater swept area) are huge for severe duty & durability. Sickly EPA-era late '70's to early '80's Corvette's with 180HP came with 11" clutch for a good reason. They last 100K mi under spirited use...no babying.
4) Folks who insist on ZERO rollover noise are stuck with dual mass flywheel and tiny clutch. In this case, durability can be addressed to some degree by installing a higher temp clutch disc and matching pressure plate that does not have the stupid SAC auto-adjuster. A plug-and-play solution of this type is offered by sponsor UUC and it sounds like non-sponsor Dinan is releasing one soon.
Last edited by Lscman; 24th November 2005 at 17:41.
@lscman: so the UUC 11" clutch combined with the lightweight flywheel looks pretty much like the way to go. I guess I'll go for that once my stock clutch is gone. Thanks for the info!
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