MIB

Hey Dick,

No I didn't weigh it and it really bugs me now.

I do know that it is a lot lighter than the Stock Dual mass.

At a guess I would put it between The Dinan Stage 1 and Stage 2. Sought of a 1.3 Stage.

__________________
///Mark 03 E39 M5 MIB He's in Apples hands now.

HBRAMSTEDT

Light flywheels have the most pronounced effect at lower vehicle speeds when the change in crank velocity is the greatest. The increased mass of a given flywheel will resist changes in velocity, acceleration. At high speed,
engine r.p.m.s don't vary as much as they do in initial acceleration from a stop. Therefore, light flywheels have little or no effect at high speeds. In fact, I surmise that at high speeds, under aerodynamic load, the lighter flywheel may not maintain momentum between shifts as well as the heavier
one, possibly being slightly detrimental.

Anita

Thank you all for the info. Okay, so in what driving events would the flywheel replacement make any sense/difference--for low speed autocross events, which I have not done with my M5, high speed autocross courses (2 miles in size) or a road course like Road America? Also, I think part of the tech's rationale for doing a flywheel swap during the clutch replacement was to save labor costs. I wonder how BMW would like that being done during a warranty clutch replacement ?!?

Bill: I think you are correct about my beer consumption--I really should make it more then one so I can figure out what people are telling me. All the info above may require 2 or 3 at least. Seriously, this past year has been a real learning experiencing for me--I come from a background of never having done any track events and knowing very minimal things about the workings of cars to where I am today, which isn't that much further--HA HA. It's been a steep learning curve, but I've been having a blast doing all I've done.

Anita

__________________
"When will I know that I really can't go
To the well once more time to decide on
When it's killing me, when will I really see
All that I need to look inside
Come to believe that I better not leave
Before I get my chance to ride" RHCP "Snow"

robmorris3

Ok, my clutch is shot and my dealer won't take care of it under warranty. So, my thinking is if I have to shell out the $ for a clutch, i don't want to put the same piece of junk that's in there now. however, after reading numerous posts on this clutch issue, I have learned there are tradeoffs and I am now thoroughly confused. I don't like the idea of hearing some trashy sounding noise coming out from my $70k plus car. I also don't want to relpace my clutch in another 20k miles. I would rather fix the problem now and fix it right! The thing that makes me mad is that BMW is refusing to acknowledge that this amounts to what should be considered a design defect.

My question is, since I have to replace the clutch on my dime is it worth it to replace the flywheel when everything is already apart and also spend the extra $ to get a racing clutch? What is the strongest and most cost effective solution without having to listen to that lash noise?

MIB

Hey Rob,

Its simple. To fully remove the problem, you introduce the roll over noise at idle only.

Your choice. A little noise, only when the clutch is out, at idle, (Most of the time it is in and silent), or you can replace your clutch all the time.

The real heart of the problenm is the Dual mass flywheel and lack of clamping pressure.

Because the dual mass is so flexible, they can't apply decent clamp. Remove the dual mass, and you can up the clamp.

But the dual mass is what keeps it quiet. The choice is your. A little roll over noise, or continually facing the problem.

By raising your idle, it will quieten down the roll over noise. Its only audible from outside the vehicle. After around 900 rpm its gone. (I'm rarely below 2,000 let alone 900.)

So with an after market exhaust and raised idle it is under control. Its still there, but it is acceptable.

What is very acceptable, is Launching at 4,000 Rpm and only frying the tires and not the clutch.

Rob Levinson

To help illustrate the difference in engine acceleration between a stock flywheel and a lightweight flywheel, we have a video that demonstrates it rather well. It's from an E46 3-series, but the effect is identical with the E39 M5:

.avi format (816K): http://www.uucmotorwerks.com/flywhee...Comparison.avi

.mov format (1.35MB): http://www.uucmotorwerks.com/flywhee...Comparison.mov

I wouldn't say it's similar to Dinan's Stage 2 at all... in fact, it's not similar to anything ever put into the M5. In all reality, it's what should have been put in originally.

We have been keeping it quiet until it is ready to be released, but that date is just around the corner, before the end of February.

There are a few "field install" testers using production-quality components right now. Expect them to post their experience in the next few days.

Full details to come soon, but right now I will share these facts:

- It is a sprung-hub design for power pulse variation absorption (reduces transmission rattle).

- Total rotating mass of the flywheel and clutch assembly is reduced 13.5lbs compared to the OE M5 setup. This amount is not as much as some of the really lightweight flywheels, but it is enough for a noticeable increase in throttle response and significant rattle reduction (and complete elimination in some M5s).

- Basic clutch package is rated close to 600lb-ft. Optional clutch packages are rated to just under 900lb-ft. Got a supercharger? The UUC flywheel has already been installed behind a supercharger-equipped S62. Clamping force and materials are really beyond anything currently available.

- Pricing as a complete kit including clutch and everything you need will be comparable to other brands' flywheel alone.

- Clutch pedal feel is completely unchanged.

Simply put, it is quite literally "a lot of clutch" that will cure this ongoing issue we see with M5/Z8 owners replacing the OE setup so often. You can finally expect normal clutch life... UUC has been testing this clutch package now for over two years. When you do need a replacement clutch, the components are readily available and affordable.

__________________
Rob Levinson

robmorris3

Sounds good! Please let me know when this comes out asap. My clutch is about to go and this is my daily driver.

MIB

[quote=Rob Levinson]

Hey Rob, I don't mean to burst your bubble, but saying that something has the IDENTICAL effect as an M3 will not win you favours here.

Reduce does not = Eliminate.

So why elimination in some M5's and not others? Is that Identical to the M3's as well? I haven't looked at the clips as yet, but were they filmed with one of the GOOD ones? Do you see my point.

Since you don't put a number on that, we can't quantify it.
The reason why I say my Pressure plate gives 4,200lbs + clamp is because I saw the guy measure it, and his gauge only read that high. So I am interested in you Quantifying your statement in comparison to "Whats out there."

If that is true, then you haven't done a very good job, as the Stock pedal feels limp and like crap. Most guys would welcome a slightly firmer clutch pedal, one that has some feel to it.


Rob, I'm sure your product will be welcomed, but overstating its abilities will not. Call it as it is. Everyone who knows anything about clutches and Pressure plates and flywheels, knows how difficult it is to produce something that can do everything.

It is an extremely difficult balancing act. Showing an M3 as an example really is totally irrelavent.

I look forward to seeing and HEARING, the setups from the guys who have it.

Of course I expect it to be hugely better than stock, (Thats not hard, the bar was pretty low.)

But lets see if you deliver on the Noise factor.

Regards Mark.

Rob Levinson

Actually, I mis-wrote. I did mean to write "similar", not "identical"... and "similar" in the way that there is a similar change in any car equipped with a lightweight flywheel. Whether it is the M5, a 3-series (the video car is a 330i), a Mustang, or a Honda... the effect of a lightweight flywheel can be generally demonstrated by that video.

You should look at the video - it's showing the difference in engine acceleration speed between the OE flywheel and a lightweight setup. It's quite interesting.


I believe I made that quite clear... "significant rattle reduction (and complete elimination in some M5s)" in that post.

Answering those in reverse order, the video shows nothing regarding rattle or not. It's a close-up shot of two tachometers showing rev speed, no audio whatsoever.

As to why in some M5s and not others, there are a number of factors that determine transmission rattle due to removal of the dual-mass flywheel's power pulse variation absorbing capabilities:

1) Build tolerance of each individual transmission - as much as we like to think BMWs are "minted" perfectly, the truth of the matter is that variations exist between components. In these transmissions, some are looser than others, more likely to rattle at idle with a lightweight flywheel.

2) Wear of the individual transmission - whether thorough mileage, contaminants, or hard use, the fact remains that each transmission wil change it's propensity to rattle as time passes, and each one in slightly different ways than every other one.

3) Condition or type of transmission fluid - thinner fluid has less damping effect than heavier fluid, that's a basic concept. The OE fill changes viscosity as it ages or is used (and more or less depending on usage style). Likewise, the use of alternate fluids will change the damping effect. Whether the M5 has OE, Swepco, Royal Purple, Redline, or Amsoil will change how much damping there is from viscosity and the effects of the additive packages.


We will be supplying data on the website shortly. Bear with me, I am not ducking your question but looking to answer it more completely in due course.


Then I have the answer you will really like; our setup includes a different slave cylinder, matched to this clutch. The original slave cylinder can be retained, and the effect is a firmer pedal feel. Best of both worlds - the M5 owner can choose the pedal feel he prefers.

Again, not to duck the question, but I ask a small amount of patience until we publish the details. I think you will see the capabilities of this setup have not been overstated.

Trust me, my disappointment in the original BMW design is substantial. The fact that the E39 M5's clutch is not significantly different than that of the 5-series from 20 years ago despite the big increases in power and chassis weight is simply astonishing.

While I would never guarantee an absolute absence of slight rattle (see the list of factors above), I can say that the net result is not like any other aftermarket lightweight flywheel, and is similar to a lightened OE flywheel.

MIB

Thanks for your speedy reply Rob,

Just keeping you honest buddy.

It is quite clear that UUC have gone the extra yards to come up with a soloution.

My setup was a one off, designed specifically to my needs. It was never meant to see production. I upgraded everything to 10 Inch for extra strength.

As soon as I saw you guys also went to a sprung centre, I knew we were looking at a serious fix. I also have a sprung centre. Mine is a five button Carbotic Clutch plate 10 inch, and a Sachs Customised pressure plate so the pedal pressure is just firm, not to heavy, not too light.

My Flywheel was a work of art. It was made from some special Steel, as I drag race as well as use it for daily driving. Whilst it is lighter than the stock Dual mass, it still has enough weight to launch the Beast, and it is expodentially stronger. So it will also handle the huge clamping pressure. We used the Stock Ring Gear, have You?

Good Job.

Your not off the hook yet, but you most certainly have gone the extra yards for a Production unit.