UUC Flywheel and M5 Clutch Kit (anyone use it?)

[Smolck]

Guys,

I have 138,500 miles on my ZHP and it is about time for a new clutch. I am going to order one in a few days and I was hopeful someone could help me out. In reading the review of the UUC light flywheel on my330i.com he says it is 13lbs. But on the ECS website which has the kit with the M5 clutch I want it says it is 8.5lbs. I am not sure I want to go that light.

I noticed the my330 review is quite old, is there a chance UUC has lightened it over the years?

Anyways, just wondering if any of you have this kit in your ZHP. I am looking for this because I am tired of the "disposable" dual mass flywheels BMW makes for $600 a pop. Not to mention the performance gains are intriguing as well.

Thanks for the help.

EDIT: Called UUC and answered my own question. The 6 speed flywheel is in fact 13lbs.

[SoarinZHP]

My opinion: STEER CLEAR. I put one on a 2002 BMW 325i along with the organic high performance disc. I considered it ruining my car. I couldn't stand the gear lash when idling in neutral and the clutch was HEAVY. Because the flywheel was so light, launching under normal conditions was a PITA. Made the car difficult to drive. Also, because the flywheel is so light, when the clutch was disengaged (as in coming to a red light or placing in neutral) the car would stall because there was no momentum as with a dual mass flywheel. The car did not have time to adjust due to the lack of rotational mass. Vibrations transferred through the car because it is not dual mass.

There was a minor performance gain - I didn't think it was at all worth it. I'd never put one on my ZHP - I also read the flywheel on a ZHP is lighter than that on a standard BMW.

I'd be interested in hearing other people's opinions. I am only sharing my experience with it.

[danewilson77]

^good info. Committed to memory.

HTC Thunderbolt+TT

[az3579]

I don't know if my experience could help you, but I had a 13lb flywheel on my E30 with E36 M3 drivetrain. The chatter when not in gear was mind blowing. It's very loud, and quite frankly sounds like something was loose in the drivetrain (the sound was normal - supposed to sound like that).

The acceleration, however, was unbelievable. The car wanted to rev much easier with the light flywheel. Rev matches were cake, as throttle response was greatly improved. Of course, this was on a car that still actuated the throttle body with a cable, but for the performance it was worth it. The chatter was really getting on my nerves though before I sold the car.

Taking off wasn't difficult at all for me. I think it's only a problem for people with certain driving styles. I've driven one with an 8lb flywheel as well and that wasn't difficult to drive either.


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[Hornung418]

There was a minor performance gain - I didn't think it was at all worth it. I'd never put one on my ZHP - I also read the flywheel on a ZHP is lighter than that on a standard BMW.

I'd be interested in hearing other people's opinions. I am only sharing my experience with it.
Myth busted. No Lightened Flywheel in the ZHP from the factory.

If this is a DD, move on. Check out the Turner flywheel, Grand Am Cup Legal Lightweight Steel Flywheel (http://www.turnermotorsport.com/p-1020-grand-am-cup-legal-lightweight-steel-flywheel-e46-m3-330i-mz3-coupe-z4-30i.aspx). It's a steel single-mass, so more power is transferred to the wheels, and is 20 pounds, five pounds lighter than stock so your throttle response will be a little more responsive.

Remember, if your ZHP is not a race car, you'll want some momentum on your drive-train to decrease wear.

Best of luck with the decision.

[SoarinZHP]

OMT - I think if you were going to track your car the negatives probably wouldn't be that big of a deal.... For a DD, I would definitely think twice, maybe three times about it...

[az3579]

Myth busted. No Lightened Flywheel in the ZHP from the factory.


Really? I thought the factory one chattered because it's lightened. Why does it chatter then if it's not lightweight? Any idea?


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[Smolck]

My opinion: STEER CLEAR. I put one on a 2002 BMW 325i along with the organic high performance disc. I considered it ruining my car. I couldn't stand the gear lash when idling in neutral and the clutch was HEAVY. Because the flywheel was so light, launching under normal conditions was a PITA. Made the car difficult to drive. Also, because the flywheel is so light, when the clutch was disengaged (as in coming to a red light or placing in neutral) the car would stall because there was no momentum as with a dual mass flywheel. The car did not have time to adjust due to the lack of rotational mass. Vibrations transferred through the car because it is not dual mass.

There was a minor performance gain - I didn't think it was at all worth it. I'd never put one on my ZHP - I also read the flywheel on a ZHP is lighter than that on a standard BMW.

I'd be interested in hearing other people's opinions. I am only sharing my experience with it.

The one for the 5 speed car is 8.5lbs so it may have been really bad. Several people I have talked to say they have this kit and love it.

[SoarinZHP]

If one is capable of doing the job themselves, I'd say try it and see if you like it. Then you'd know for sure and could easily go back to a stock setup. I was not comfortable with my mechanical skills and had a shop do it - plus I needed the car back ASAP. At the time I was not (and still not) in the financial position to have a clutch replaced so frequently.

[Hornung418]

Really? I thought the factory one chattered because it's lightened. Why does it chatter then if it's not lightweight? Any idea?


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Well there is only one part number for six speed equipped e46 flywheels...21207533868. And Barry (Mr.Maico) has literature somewhere that disproves this theory.

Do you stock ZHPer's experience any chatter in gear at low rpm or in neutral at a standstill? Because I've only heard of the Stock Flywheel Chatter issue upon shutdown with the car in gear/clutch depressed.

[Smolck]

If one is capable of doing the job themselves, I'd say try it and see if you like it. Then you'd know for sure and could easily go back to a stock setup. I was not comfortable with my mechanical skills and had a shop do it - plus I needed the car back ASAP. At the time I was not (and still not) in the financial position to have a clutch replaced so frequently.

Yea, I do all my own work and work on BMW's as a side business. But I don't want to do it more than once. The stocker went 138k miles, maybe I should stick with stock.

And wow, that Grand Am flywheel ain't cheap. $900, ouch!

[Hornung418]

Grand-Am Fly should outlast anything you are gonna throw at it on the street! Would make a nice tax-return present ;)

[az3579]

Do you stock ZHPer's experience any chatter in gear at low rpm or in neutral at a standstill? Because I've only heard of the Stock Flywheel Chatter issue upon shutdown with the car in gear/clutch depressed.

I get the chatter when in neutral.



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[SoarinZHP]

A little chatter in neutral. At shut down with the clutch depressed or in neutral... Always.

[kayger12]

No neutral chatter.

Shut down in neutral, yes, but not if clutch depressed.

[Hornung418]

Those responses are why I think this is limited to Six Speed transmissions. But it is not a bad thing, no harm is done to the car.

However with the extremely lightened flywheels, they are meant to have a load on them at all times, except when starting the race...You can get away with a few pounds on a DD, but I would never go as low as 8.5 pounds...That's ridiculous.

But the dual-mass flywheel is for the mass populations, so there are plenty of upgrades available for the enthusiast owner, but normal weight with a single mass is the best option for a lightly modded Daily Driver, IMO.

[YoitsTmac]

Bump. So are there any Lightweight SMF's still in production? Would love 20lbs, but the one in this thread seems discontinued now.

[Prestovie]

I DD a 15lbs flywheel, I'll have to check in the records who made it, but even though it was a learning curve I don't see myself going back from it. 8.5? Sounds a little extreme for DD purposes, the neutral chatter as is is already quite obnoxious, but imo it adds character :P
Interested to see which you go with, always good to remember this stuff for the next time mine needs to be replaced(knock on wood)

[YoitsTmac]

I DD a 15lbs flywheel, I'll have to check in the records who made it, but even though it was a learning curve I don't see myself going back from it. 8.5? Sounds a little extreme for DD purposes, the neutral chatter as is is already quite obnoxious, but imo it adds character :P
Interested to see which you go with, always good to remember this stuff for the next time mine needs to be replaced(knock on wood)

I found a 14lb from clutch masters but can't find anything between 14lbs and 25lbs. If you know something I don't then please let me know!

[RWD Twisted]

SPEC makes the SB07S 20# steel single flywheel for the ZHP.

[jason89i]

My opinion: STEER CLEAR. I put one on a 2002 BMW 325i along with the organic high performance disc. ...............and the clutch was HEAVY. ..........

Just a data point.

force required to press pedal to floor:
26 lbs. = oe
46 lbs. = clutchmasters
66 lbs. = uuc

You can replace pressure plate on the uuc for different results.

[YoitsTmac]

Where did you obtain this data?

[jason89i]

Where did you obtain this data?

I put a 2ft long 2x4 on the clutch pedal, put a digital scale on the other end, sat down and pushed on the scale. Did it 3-4 times for each car. The ts2 car (uuc clutch) measured more irratic. I think after 40k miles the clutch pedal bushings we’re wearing. Got measurements from 62-68ish.

So not perfectly scientific, but more imperial data than internet “hear-say” of a “heavy” clutch.

I’ve logged nearly 200k miles in 3 ZHP‘s, spun lots of wrenches and had some dedicated track cars. my tastes have changed as I’ve gotten old…….. so not sure my opinion is of any benefit.

[ZHPizza]

I put a 2ft long 2x4 on the clutch pedal, put a digital scale on the other end, sat down and pushed on the scale. Did it 3-4 times for each car. The ts2 car (uuc clutch) measured more irratic. I think after 40k miles the clutch pedal bushings we’re wearing. Got measurements from 62-68ish.

So not perfectly scientific, but more imperial data than internet “hear-say” of a “heavy” clutch.

I’ve logged nearly 200k miles in 3 ZHP‘s, spun lots of wrenches and had some dedicated track cars. my tastes have changed as I’ve gotten old…….. so not sure my opinion is of any benefit.Honestly way more scientific than most forum data. Thanks for gathering/sharing!

[YoitsTmac]

+1. Not many people would go that far so it's appreciated! Have you driven the clutch masters? The stock one is undoubtedly light but 46lbs with your data is a near 2x increase in pressure. Do you think it is good for a daily?

[jason89i]

+......Have you driven the clutch masters? ....... Do you think it is good for a daily?

Yes, Ive logged 30k on the clutchmaster. I initially thought it was great, but fell out of love with it as I got older. Back in my youthful days I daily drove an s54e30m track car on 900# springs...... back then it would have been perfect. But now im getting old and think its "a little too heavy." My cushey 340i clutch is xxx#, so personal preference would be somewhere in the middle.

Now, the uuc, I hope you do your weekly squats. But great on the track.

ps. I broke springs in both the uuc and clutchmaster sprung hubs within the first 5k miles.

[YoitsTmac]

That's understandable. I don't think I would like a clutch that made me feel that way either. Happy to hear you have a B58 manual. Those things are insane. Can I ask what you think of the shifter? I'm half contemplating one myself.