'88 325is M30 street car-->S54 -->S50 -->M54 Enduro Race car

[nando]

I'm talking about at idle. a lighter flywheel definitely makes the trans rattle more at idle.

if springs didn't do *anything* for clutch engagement, then why do un-sprung clutches and single mass flywheels engage so harshly?

[LJ851]

I'm talking about at idle. a lighter flywheel definitely makes the trans rattle more at idle.

if springs didn't do *anything* for clutch engagement, then why do un-sprung clutches and single mass flywheels engage so harshly?

The rotational springs in a clutch hub are primarily for softening the engagement of the clutch.

Dual mass flywheels are primarily for absorbing vibrstion from the trans and crank, making the low rpm usage more polite and quieting the gearbox.

Does bmw put rubber in the middle of a dual mass flywheel like porsche does?

[Jb325is]

I'm thinking sticking to the dual mass flywheel and getting a solid hub clutch is the way to go. I've been reading a lot of stuff on m3forums and the track guys are complaining about big vibrations around 5500 with the lightweight flywheels, as well as harmonic damper failures. Definitely not something I want to take a chance with.

Anyone used clutchnet clutches? I'm thinking of buying a disc from them and using it with my m5 pressure plate.

[LJ851]

I'm thinking sticking to the dual mass flywheel and getting a solid hub clutch is the way to go. I've been reading a lot of stuff on m3forums and the track guys are complaining about big vibrations around 5500 with the lightweight flywheels, as well as harmonic damper failures. Definitely not something I want to take a chance with.

Anyone used clutchnet clutches? I'm thinking of buying a disc from them and using it with my m5 pressure plate.

I like this idea best, you can always change the flywheel at a later date if you are so inclined.

[The Dark Side of Will]

I'm thinking sticking to the dual mass flywheel and getting a solid hub clutch is the way to go. I've been reading a lot of stuff on m3forums and the track guys are complaining about big vibrations around 5500 with the lightweight flywheels, as well as harmonic damper failures. Definitely not something I want to take a chance with.

Anyone used clutchnet clutches? I'm thinking of buying a disc from them and using it with my m5 pressure plate.

I think Vorschlag (Vorshlag?) has dampers that can handle track abuse with lighter flywheels.

I'm talking about at idle. a lighter flywheel definitely makes the trans rattle more at idle.

if springs didn't do *anything* for clutch engagement, then why do un-sprung clutches and single mass flywheels engage so harshly?

Do unsprung clutches with organic linings and marcel disks engage harshly? Or are we talking about pucked units with copper ceramic friction material?

The rotational springs in a clutch hub are primarily for softening the engagement of the clutch.

I disagree totally. Check how much torque it takes to bottom out those springs... just a handful of ft lbs. They don't have any meaningful capability relative to the torque it takes to move the car.

Dual mass flywheels are primarily for absorbing vibrstion from the trans and crank, making the low rpm usage more polite and quieting the gearbox.

Does bmw put rubber in the middle of a dual mass flywheel like porsche does?

Yes, BMW's dual mass has rubber in it.
The overall weight of the flywheel and the fact that it's a dual mass system serve two different functions.
Weight reduces the severity of power pulses while the characteristics of the 2nd mass quiet gear rattle and assist the harmonic balancer to some extent. There's no reason that a dual mass flywheel couldn't be designed at 10 lbs instead of 30 and still keep gear rattle mostly quiet (other than maybe the rubber would have to be too soft to last in normal driving)

[CorvallisBMW]

sub'd

[vitiokas95]

I am starting my S50 swap soon and can't decide if I should stay with 15'' wheels or upgrade to 17''. What advantages or disadvantages for switching to 17''? My car is used for track only.

[nando]

Dude, way OT. Start your own thread in the wheels section.

[modernbeat]

I think Vorschlag (Vorshlag?) has dampers that can handle track abuse with lighter flywheels...

Sorry, we don't have one. We looked into making custom E46 non-M dampers, but the guys we were working with found that their solution was dimensionally impossible to fit into the space required.

VAC may have something...

[gills]

Hey jb, this might be a little far ahead, but what tachometer solution are you using for the 8k RPM S54 redline?

[plmichal]

I disagree totally. Check how much torque it takes to bottom out those springs... just a handful of ft lbs. They don't have any meaningful capability relative to the torque it takes to move the car.

I'm leaning towards this, it makes sense when you put it that way. But I would really like to hear more (professional) input regarding the dual mass flywheel vs clutch spring combo.

[The Dark Side of Will]

Sorry, we don't have one. We looked into making custom E46 non-M dampers, but the guys we were working with found that their solution was dimensionally impossible to fit into the space required.

VAC may have something...

Ok, thanks.

I remember from either the Corner-Carvers or Bimmerforums thread about the 330ci that you were trying to get a custom balancer made after you lunched about 5 M54B30's from spinning them to 7k. Interesting to hear that a unit with the necessary capabilities couldn't be made to fit.

Harmonic balancers are interesting business. I've heard that the one on the Ford GT weighs more than 20 lbs.

[gills]

Any thoughts on what you're going to do for exhaust?

Picking up my S54 this weekend :)

[Jb325is]

I think I'm going to do single 3.5" oval tubing, I've always wanted to use the stuff so why not now? Not sure what muffler I want to use though, I haven't really shopped around yet.

I just payed the remainder on my headers and my s54 should finally be arriving on Monday. Can't wait!t

Oh, and I missed your comment earlier, I have no idea what I'm going to do for a tach. I hadn't thought about it until you said something. What are the options? I'm really considering ditching the cluser and running a STACK dash or AIM/Race Technologies if I can afford it

[gills]

I think I'm going to do single 3.5" oval tubing, I've always wanted to use the stuff so why not now? Not sure what muffler I want to use though, I haven't really shopped around yet.

I just payed the remainder on my headers and my s54 should finally be arriving on Monday. Can't wait!t

Oh, and I missed your comment earlier, I have no idea what I'm going to do for a tach. I hadn't thought about it until you said something. What are the options? I'm really considering ditching the cluser and running a STACK dash or AIM/Race Technologies if I can afford it

Not sure on the options, which is why I'm asking you ;) The E30 M3 cluster maxes out at 8k rpm vs 7k rpm for the M20 tachs, so I'm assuming an E30 M3 cluster or tach would be ideal to keep an OEM look without the tach needle swinging past the 7k rpm limit to a virtual 8k RPM. Of course, that's pure speculation on my part. People have used the M20 7k rpm cluster, but I have yet to find out if it functions how I described or functions normally. As in scaled to a 8k rpm redline of the S54 (tach shows 6300 rpm but really means 8k rpm), which I'm not sure is possible.

Those headers you got look great. Do all aftermarket S54 headers fit in an E30 with just some clearance required on the subframe and re-positioning of the ARB?