We have just added a new 12.8 lb Street flywheel option for our twin disc clutch. We still offer the 5.5 Race flywheel of course.
The intent of the heavier flywheel was to make it more streetable. More torque capacity than any single 9" (OEM 1.8) disc with a lighter pedal. The twin is a much heavier pedal than a stock clutch but still lighter than the high capacity 1.8 clutches on the market.
As a test, we let the clutch out slowly in reverse up a slight incline, no throttle and the car would chug away on idle control without stalling. The 5.5 flywheel is very easy to stall in comparison.
The other bonus is a huge reduction in NVH. The Race flywheel allows every buzz and rattle to enter your back teeth. It's a race clutch, no sugar coating it.
The Street flywheel feels like a normal 1.8 clutch with light flywheel. Quiet, not buzzy. The perk is that it will hold 400 lbs/ft and your SO can drive it.

Simple choice between the two. The Street flywheel is still fast revving, holds torque, is quieter than the Race and very driveable on the street. The Race flywheel sucks everywhere, makes your drivetrain sound broken except exiting pit lane, revs like a superbike and is godlike on track.

https://supermiata.com/miata-twin-disc-clutch.aspx

 

Why is the Kevlar disk more expensive if it holds less power? Does it modulate better?

 

Yes. The ceramic disc is basically an on/off switch. Not a clutch in the traditional street car sense. The Kevlar disc is what is in Bullet now and quite happy at 400whp with the sequential banging away. Not sure who would actually need the ceramic but we offer it just the same.

 

Can the new flywheel be purchased separately ? I have a twin disk here that I've not installed yet ..

 

Not at this time. Separate Street flywheels are many months out.

 

So, how would the street version compare to the FM stage 2 clutch? Both handle the same power more or less (enough). And the Fm has a 10.3lbs flywheel. Is the twin more street friendly?

 

No idea.

The Street Twin flywheel is 12.8lbs but 50mm smaller diameter. everything else being equal a multi disc clutch will always modulate better than a single disc. In this case they're not exactly equals so who knows.

 

Cost differences aside, for street use would you recommend the Street Twin over the Sprung Puck w/lightend flywheel?

 

The FM2 will not hold 400 wtq. Mine smokes in 4th gear with much less than 400. I might be making 350, maybe.

 

Primary question is torque capacity. If you need the high torque capacity the twin is the way to go. The Street Twin is far easier to modulate than our own 1. 8 puck.

 

Fun fact: our GT350 OEM clutch is a twin disc.

 

That's what I wanted to hear

I hate my current clutch, but I don't want to buy something I'm going to grow out of. I want a clutch that will out last any power upgrade up to the point I break my 6-speed and start looking at the K-Miata BMW solution. But I daily drive my car, so easy modulation in stop-go traffic is important. I lift, so heavy pedal isn't a problem. I was leaning towards FM stage 2, but my loyalties lie with 949.

Street Twin for the win.

God, the exchange rate, shipping, import duties and tax are going to kill me, but if I never need to touch my clutch again I'll be happy.

 

Supermiata actually

949 Racing is just wheels

 

I knew that, but old habits die hard!

Ironically, your wheels are one of the only parts I haven't gone with from your catalogue. I'll be waiting for Silver to make a come back.

 

Supermiata Twin (12.9 lb) with Kevlar/Carbon discs on order. Will report once installed.

 

edit: nvm

 

I just upgraded my FM2 clutch that has a 13.6lb Maruha flywheel for the Supermiata twin carbon/kevlar with the 12.8lb flywheel. I purchased the 12.8lb flywheel directly from Competition Clutch as my clutch came with the race flywheel.

The Supermiata twin has a noticably heavier pedal than the FM2 but is definitely streetable.

The Supermiata is *very* easy to modulate. Definitely no harder to drive (once you get used to the heavier pedal) than the FM2. Definitely not an on/off switch. I drove home from the shop in stop and go rush hour traffic and didn't stall once. It's arguably easier to drive than the FM2 since the FM2 has the annoying feature of changing its bite point depending on how hot it gets.

As for NVH, the 12.8lb flywheel of the Supermiata has a *lot* more when coasting down in gear. Lot's of loud buzzing...so much that I need to double check that my exhaust isn't rubbing and vibrating somewhere. In comparision, the FM2 with the 13.6lb Maruha flywheel was silent. Previously I had the FM 10.3lb flywheel and it made a similar amount of noise as the Supermiata 12.8lb flywheel.

 

Can you email me at info@949racing.com when you get a chance please

 

This doesn't thrill me. I just changed my Quaife gearbox to a 6-speed in order to reduce NVH (emphasis on "N"). Really hope I'm not trading one issue for another.

 

As expected with a rigid (not sprung) disc. It is still a clutch designed to handle 400lbs tq. It should be possible, if someone were inclined. to design and manufacture a twin sprung disc system. Our GT350 OEM clutch is a twin sprung.
The spring center, while adding mass and failure points, absorbs most or all of the natural driveline noise in a stock car. Delete the sprung center and even a bone stock Miata will rattle and buzz on decel.