Custom LWFW

[rudypoochris]

Hey Guys,

I am getting ready to upgrade my clutch soon and, as many of you have noticed, there are not many options for power levels past 500hp. Currently I am leaning towards Spec 3+ or HPF. The problem I am having is that I want to go with a flywheel lighter than stock but really am not a fan of the rattle in the least. For this reason I have contacted JB Racing (jbracing.com) who manufacture custom flywheels and flywheels for other European platforms to find out if they would be willing to make a flywheel for us that is lighter than stock while keeping rattle in check.

I was thinking of selecting either the stock pattern (HPF) or Spec 3+ as the target for this. Are any of you interested? Would you be willing to do a group buy?

Here is the correspondence:

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Hello JB Racing,

I will be in need of an upgraded clutch for my e92 335i soon. The stock flywheel is too heavy (believe it's around 28lb) for my liking but all of the single mass replacements (10-14lb) have been known to produce extreme chatter. Unfortunately most of the high torque clutches require the use of an upgraded single mass flywheel.

Can JBR manufacturer/modify/supply a lighter than stock single mass flywheel that does not cause gear chatter or other excessive noise? I could probably find enough people to do a group buy if needed.

Thanks,

Chris

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Chris,
We appreciate your interest and inquiry regarding a lighter flywheel for your car. We do not presently manufacture a flywheel for your application, however we would certainly entertain doing so if you can provide us with a reasonably new OE flywheel that could be used for design mock-up. You mentioned the use of “high torque clutches” – please clarify if you are referring to an OE style replacement clutch?, or a small diameter/multi-disc competition style clutch as any new flywheel would have to be designed to match the clutch style. Of course in either case, this would be more attractive if multiple flywheel units are being purchased and we can discuss this should you elect to proceed.

All aftermarket flywheels are essentially Single-Mass construction which necessitates some degree of compromise between reduced weight/moment of inertia (performance gain) Vs the acceptable transmission gear noise (gear lash). During the last 12-18 months, we have built some very successful “mid-weight” flywheels (for OE style clutch) in steel for the E36 & E46 M3 applications. Both of these “mid-weight” flywheels were designed to mitigate the gear chatter/transmission noise while retaining as much performance gain potential as possible. If your OE flywheel has a static weight of 28 lbs., then I would estimate something in the 17-20 lb. range would quiet things considerably. Please understand though, that drivetrain dynamics will differ in each application therefore there is no “magic weight” value that can guarantee elimination of this annoyance. Also understand that the weight positioning in the flywheel can & will affect the flywheel moment of inertia (MOI) which is the real controlling factor with respect to both the noise issue, as well as the performance gain.

If you would like to pursue this project, then I suggest you give me a call and we can discuss the requirements and what’s necessary to proceed.
Thanks,

Dennis R. King
Sales & Marketing Mgr.
JB Racing, Inc.

[rudypoochris]

I think something in the 17lb weight range could satisfy the need for quicker more performance oriented shifts while mitigating the majority of the rattle. I will call Dennis and see if he feels similarly. I will also inquire about shims or other methods of preloading the input shaft to avoid gear lash.

[bigdnno98]

I have a DMFW I would loan for mock up as long as I get it back.

[Carl Morris]

Is there no reason to pursue a light aftermarket heavy duty DMFW? I realize it could be expensive, and maybe the 1M unit is close enough for those who can bolt it on, and maybe there's no such thing as a bulletproof DMFW, but I'm still curious. What I like about the DMFW is being able to use a solid hub disk with much less noise than when you use a solid hub on a traditional SMFW.

[rudypoochris]

Is there no reason to pursue a light aftermarket heavy duty DMFW? I realize it could be expensive, and maybe the 1M unit is close enough for those who can bolt it on, and maybe there's no such thing as a bulletproof DMFW, but I'm still curious. What I like about the DMFW is being able to use a solid hub disk with much less noise than when you use a solid hub on a traditional SMFW.

Interesting. It most certainly would be more expensive. The downside to the DMFW in my opinion is the fact that it can slip at high loads (it is designed to when capacity is exceeded). This makes me worried since the last thing we want is an aftermarket slipping flywheel.

What does the 1M flywheel weight? Can it be used instead of the stock flywheel in the 335i and 135i? Is it the same dimensions?

[Carl Morris]

Interesting. It most certainly would be more expensive. The downside to the DMFW in my opinion is the fact that it can slip at high loads (it is designed to when capacity is exceeded). This makes me worried since the last thing we want is an aftermarket slipping flywheel.

What does the 1M flywheel weight? Can it be used instead of the stock flywheel in the 335i and 135i? Is it the same dimensions?

I tried to learn more about DMFWs in general and read about ones with torque limits that were designed to slip above the limit. Can you confirm whether ours has that capability? It seemed like maybe they were talking about particular commercial diesel models or something. If ours can, that might explain why I am seeming to overwhelm my clutch on a hard 1st gear AWD takeoff yet it recovers so quickly...is it possibly I'm actually slipping the flywheel instead of the clutch?

There are other threads you can check about the 1M flywheel. Anything I say might be badly remembered. After I looked them up it appeared that they would not bolt on to my 2008 but might bolt onto newer N54s.

[dzenno@PTF]

I've looked at our DMFW many times and I don't see any way this can slip at any load. It just has a bit of springiness for smooth the engagement as its two piece but there's nothing in it to allow for slip

[Carl Morris]

I've looked at our DMFW many times and I don't see any way this can slip at any load. It just has a bit of springiness for smooth the engagement as its two piece but there's nothing in it to allow for slip

Thanks. That's what I thought but hadn't actually gotten to see one yet. It is kind of fascinating that some have been built that way for other applications.