Single Mass Flywheel--

[Jonsku]

Engine: E34 M60 (circa 1995), Alusil
Trans: ZF 5-speed transmission (530i)
Flywheel: JB Racing E39 540i flywheel
Clutch: E36 328 Clutchmasters Organic Stage 1 kit
Slave cylinder: 530i

Is there a specific reason for using clutch that is intended for twin-mass flywheel with the single-mass flywheel? I'd have thought that e.g. E34 M5 3.6 clutch would've done the job better, though the main thing is that it works! :)

[BruceBe]

Is there a specific reason for using clutch that is intended for twin-mass flywheel with the single-mass flywheel? I'd have thought that e.g. E34 M5 3.6 clutch would've done the job better, though the main thing is that it works! :)

Define "better", and then we'll discuss it. Do you know for a fact that the e34 M5 setup will work?

-Bruce

[Jonsku]

Define "better", and then we'll discuss it. Do you know for a fact that the e34 M5 setup will work?

-Bruce

Ok, i was a bit unclear.

The clutch disc itself is pretty similar in twin-mass flywheel setups (240mm disc on M60B30 / M62's / M52B28 etc..) as the disc in single-mass flywheel setups (M30, S38B36), except that the twin-mass flywheel disc does not have the dampening springs.

The only problem, from my point of view, is the pressure plate. The twin-mass flywheel pressure plate won't work as it's different height than the single-mass flywheel pressure plate, and the single-mass flywheel pressure plates might have different heights (M30 and S38 should be similar, as well as M60 / M62 / S62, maybe even M52?).
The clutch disc itself is no problem, as you can use M62B44 clutch disc for 6-speeder or M60B30 for 5-speeder. The disc won't have much to say for the "torque durability" - it's the pressure plate that is the decisive.


From all that i finally come to the point, which is that if i understood correctly, you're using single-mass flywheel with full twin-mass flywheel clutch setup. There are two concerns in that which crossed my mind;

1) clutch-disc intended for twin-mass flywheel does not have dampening springs, which causes additional noise from gearbox etc (no problem in track-cars, and actually i do also have such setup in my cabrio as i couldn't find anything else suitable, works fine though 'box rattles a bit).
2) The "real problem" is that the pressure plates used with twin-mass flywheels seem to be much weaker than the ones used with single-mass flywheels. Combine that with the "torque shocks" that are now not dampened by a) twin-mass flywheel or b) clutch disc dampening springs, and you may have created yourself a problem.

When i built the cabrio i had full S62B49 flywheel / clutch package to play around with and i was very surprised of how weak the pressure plate was, compared to pressure plates used with single-mass flywheel clutch setups. There really is a huge difference, and thus i wouldn't use those in "now un-dampened driveline".


However, those are just couple of things that crossed my mind, as i'd have expected that you'd have used pressure plate from M30 / S38, as they're made for heavy use and single-mass flywheels with 240mm clutch disc. Anyhow, let me know what you think as it seems you've done the build in pretty good quality and thought of these things, not just thrown it all together so you must have some reasoning behind these solutions, right? :)


Just my 2 cents... (or however the saying there goes).

[BruceBe]

Ok, i was a bit unclear.

...

From all that i finally come to the point, which is that if i understood correctly, you're using single-mass flywheel with full twin-mass flywheel clutch setup. There are two concerns in that which crossed my mind;

1) clutch-disc intended for twin-mass flywheel does not have dampening springs, which causes additional noise from gearbox etc (no problem in track-cars, and actually i do also have such setup in my cabrio as i couldn't find anything else suitable, works fine though 'box rattles a bit).
2) The "real problem" is that the pressure plates used with twin-mass flywheels seem to be much weaker than the ones used with single-mass flywheels. Combine that with the "torque shocks" that are now not dampened by a) twin-mass flywheel or b) clutch disc dampening springs, and you may have created yourself a problem.

When i built the cabrio i had full S62B49 flywheel / clutch package to play around with and i was very surprised of how weak the pressure plate was, compared to pressure plates used with single-mass flywheel clutch setups. There really is a huge difference, and thus i wouldn't use those in "now un-dampened driveline".


However, those are just couple of things that crossed my mind, as i'd have expected that you'd have used pressure plate from M30 / S38, as they're made for heavy use and single-mass flywheels with 240mm clutch disc. Anyhow, let me know what you think as it seems you've done the build in pretty good quality and thought of these things, not just thrown it all together so you must have some reasoning behind these solutions, right? :)


Just my 2 cents... (or however the saying there goes).

Well, you've touched on a bunch of things...let's drill down a bit.

Solid vs. sprung-hub clutches - this is a driver-comfort and NVH (noise, vibration, harshness) compromise. Sprung-hub clutches ease take-up, and can cut down on rattle/chatter. Since a clutch is slipping for some period of time, by definition, in every shift event, ultimately it is the surface area of the clutch, the coefficient of friction of the clutch material, and the clamping force of the pressure plate that determine if a particular clutch/PP assembly can handle the torque output of the engine. For a daily-driver/cruiser I agree, the dampened clutch helps reduce NVH, and adds to driver comfort.

How did you determine that the PP used in the dual-mass setup was "weaker"? Did you measure the clamping force of the PP vs. a single-mass package? A softer clutch pedal does not necessarily translate to a "weaker" pressure plate. That difference can be entirely determined by the ratio of piston areas between the clutch master and slave cylinders.

And then there's the issue of V8 compatibility and packaging. Who makes a single-mass lightweight flywheel, compatible with a dampened clutch package that is up to the task (even the e34 M5 has 30 ft-lbs less torque output than the M60), and will not only bolt-up to, but actually offer a ring-gear diameter that allows you to start the car?

-Bruce

[Jonsku]

the coefficient of friction of the clutch material, and the clamping force of the pressure plate that determine if a particular clutch/PP assembly can handle the torque output of the engine.

Yes of course. And as said earlier, the clutch disc material used in the clutches is virtually the same (dampened vs. un-dampened clutches)

How did you determine that the PP used in the dual-mass setup was "weaker"? Did you measure the clamping force of the PP vs. a single-mass package? A softer clutch pedal does not necessarily translate to a "weaker" pressure plate. That difference can be entirely determined by the ratio of piston areas between the clutch master and slave cylinders.

Have you compared the actual pressure plates e.g. between S62 and S38B36? The difference pretty big, and i'm not surprised that virtually all S62's confront clutch-slippage with original parts.. And as also said earlier, i'm very surprised that M52 clutch holds up the power, hopefully it lasts more than 1000 miles especially when the car is going to be tracked a lot. Not too nice job to change the clutch..

Clamping force is of course one thing, but the overall durability is also something that should be noted.

And then there's the issue of V8 compatibility and packaging. Who makes a single-mass lightweight flywheel, compatible with a dampened clutch package that is up to the task (even the e34 M5 has 30 ft-lbs less torque output than the M60), and will not only bolt-up to, but actually offer a ring-gear diameter that allows you to start the car?

Nobody makes those in series-production, but the world is full on milling-shops that can make such simple piece without any problems :)

[BruceBe]

...
Have you compared the actual pressure plates e.g. between S62 and S38B36? The difference pretty big...

Once again - how did you *measure* these differences? Did one pressure plate offer 20% more clamping force (at the same clutch swept area) as the other?

Clamping force is of course one thing, but the overall durability is also something that should be noted.

Yep - and the durability is predominantly a function of the three characteristics we've already talked about.

Nobody makes those in series-production, but the world is full on milling-shops that can make such simple piece without any problems :)

Yes - a qualified machine shop with accurate specifications can make such a flywheel, but I think most potential buyers would be shocked by the unit-1 cost.

Jonsku - I understand your concerns regarding the M52 pp/clutch combination, and in fact, still share some of them. However, after putting the vehicle on a chassis dynamometer, and making several full pulls and a multitude of loaded shakedown partial pulls, those concerns are substantially diminished. We had significant tire-slip issues (on 275/35/15 Hoosier R6 slicks), but not the slightest hint of clutch problems. Our vehicle is 2500lbs, with fuel and driver. Due to some sort of engine bearing failure ( :-( ), the car was only on track for a few laps - but again, zero clutch issues.

Without quantifying your concerns, all that I discern is a bunch of FUD (fear, uncertainty, doubt).

I think most of the folks doing these swaps are looking for a package that is readily available, easy to put together, and economical. By utilizing a *very* common application (M52 e36/z3/e39), the aftermarket options are plentiful, and economies of scale help keep costs (somewhat) under control. An added bonus of utilizing the e39 M62 flywheel architecture, is that an upgrade path to OBDII with an M62 gets a bit easier (crank trigger is already installed on the flywheel). For those that just want to get things running, a stock e39 dual-mass flywheel will bolt right in, as well as the stock m52 clutch kit. An upgrade path can include a lightened flywheel (JB Racing, Clutchmasters, others), and a variety of clutch material upgrades. In fact, Sachs offers a Sport pressure plate (part # 883082 720), that will add approximately 18-20% more clamping force (again, a quantified characteristic). Sachs also offers a complete "race" clutch kit for the same application.

-Bruce

[bmwmech1]

Sorry to hear about the short lived track stint, Bruce. I remember you saying something about unusually high oil pressure at one point... do you think there's a connection? I know you are probably frustrated and don't feel much like re-hashing this - understood... just curious is all.

Other than that speed bump, how did it drive/feel/handle? I'm excited to hear about it...

Garey

[Jonsku]

Bruce, i feel we share more or less the same concerns and seems that you've thought out these things earlier. That's good, as i just wanted to ensure that you know what you're doing as changing those clutches is kind of a pain in the ass - style job :D

.. though i still feel i should find out the clamping forces of different pressure plates, as i could almost bet my car that the M52 pressure plates are too weak for the M6x's.

However, it's really good if and when it holds the power on your driveline and i hope it stays that way! :)

[BruceBe]

Sorry to hear about the short lived track stint, Bruce. I remember you saying something about unusually high oil pressure at one point... do you think there's a connection? I know you are probably frustrated and don't feel much like re-hashing this - understood... just curious is all.

Other than that speed bump, how did it drive/feel/handle? I'm excited to hear about it...

Garey

Ugh.

Engine had erratic, high oil-pressure from the get-go. I took it out on track, and after 2-laps of staring at the oil pressure gauge, I brought it in and took it back to the shop. Oil pump was consuming what looked a little like glitter paint in the oil. It likely had a bearing failure, and was on borrowed time from the start. Gotta love salvage engines.

Initial impression is that torque delivery is smoother, more immediate and lower in the RPM-band than the S52US (previous engine in the car).

I didn't really have the opportunity to wring it out, but handling balance seemed similar to the 6-cylinder setup as well. With a 200lb driver and 2-gallons of fuel, our car is in the 2440lb range. I expect great things, once we have a reliable engine back in the vehicle (I've got an Alusil donor sitting on a palette, staring at me as I type this :-) ).

-Bruce

[bmwmech1]

Ugh.

Engine had erratic, high oil-pressure from the get-go. I took it out on track, and after 2-laps of staring at the oil pressure gauge, I brought it in and took it back to the shop. Oil pump was consuming what looked a little like glitter paint in the oil. It likely had a bearing failure, and was on borrowed time from the start. Gotta love salvage engines.

Initial impression is that torque delivery is smoother, more immediate and lower in the RPM-band than the S52US (previous engine in the car).

I didn't really have the opportunity to wring it out, but handling balance seemed similar to the 6-cylinder setup as well. With a 200lb driver and 2-gallons of fuel, our car is in the 2440lb range. I expect great things, once we have a reliable engine back in the vehicle (I've got an Alusil donor sitting on a palette, staring at me as I type this :-) ).

-Bruce

Ugh is right... this is my fear, since you know how easy swapping motors is in these things(insert sarcasm). At least you have another motor sitting... I think I may do new crank and rod bearings in mine as I re-assemble it. Somewhat cheap insurance. Not to go OT, but take a look at my build thread if you get a chance... Took a big step forward towards completion today...
Thanks for your update, as well... I can't F'in wait to drive mine when it's done. Your feedback is making me antsy...

Garey

[JGood]

Sorry if I'm beating a dead horse here...

If I were to find a billet steel lightweight flywheel designed for the m60b30, would that be of any value? The stock m60b30 clutch kit could then be used, and that could hold the m60b40's torque... or would it not?

m60b40 engine w/ m60b30 5-spd trans is the setup in question, obviously.

[Jonsku]

Btw, I've one set of 8kg flywheel with Sachs Racing clutch kit for sale if interested. Fits all M60 / M62 / S62 engines and 5-speed 'boxes... ;)

[Vtec?lol]

^ how much would that go for?

[Jonsku]

^ how much would that go for?

So cheap that it went already :)

[JGood]

Uhh, problem.

2000 540i dual-mass flywheel, m52 Sachs Sport clutch.









As you can see, the inner "spokes" of the disc are nearly resting on the protruding center area of the flywheel. Any pressure on the disc, and they actually touch. Obviously, even if they aren't touching now, they will when clutch material wears away.




What if i have a machine shop grind down that entire protruding lip?





I can see why the UUC e39 540i flywheel isn't an issue:





And I can see why a stock e39 540i clutch isn't an issue: