SuperMiata Twin Disc Race Clutch

The 949 Racing twin disc Race Clutch was developed to make a comprehensive kit that just drops right in. No mods to trans, slave cylinder, or fork needed. 

Approximate torque capacities:

• 250 ft-lbs Organic, single disc : N/A track cars, low boost F/I track cars 11.7 lbs
• 400 ft-lbs Organic twin disc : N/A autocrossers, N/A or F/I street cars 14.0 lbs
• 400 ft-lbs Ceramic, single disc : Drift- F/I track cars, F/I drag  11.9 lbs
• 600 ft-lbs Ceramic, twin disc : any Miata build that defies logic  14.6 lbs

Why Twin discs?

Adding a disc doubles the surface area which doubles torque capacity without any increase in pedal effort. Motorcycles and race cars have been using multi-plate clutches forever. The lower pedal effort makes a high capacity clutch a bunch easier to modulate and drive on the street. As a bonus, the twin plate discs will last twice as long as an equivalent single disc assembly.

Modulation

The ability to modulate and slip is different for each variant. All of them can be slipped to pull onto the trailer or into a parking spot slowly, the organics being easier in this regard. The ceramic single is the hardest to slip, pretty much and on/off switch. If you need to be able to launch for autocross, I recommend the twin disc as it's much easier to modulate than the single and only a bit heavier. The engagement point is much narrower than an OEM style clutch. Once you get used to it you can launch quickly, modulate and shift faster.

MOI (Moment Of Inertia)

The further from the center of the clutch you add mass, the more energy it takes to change its speed (higher MOI). So even if a 200 or 225mm OEM style clutch is the same weight, it will still have a much higher MOI than a 184mm clutch. By removing away any unnecessary flywheel material outside the friction surface, the MOI is further reduced. The lower MOI, the faster the engine will rev. In the case of the 7.25" twin, much faster. Even a fairly mild engine build will rev almost like a motorcycle with the Race Clutch. The smaller diameter clutch discs also allow the transmission input shaft to change speeds much more rapidly, making the syncros job much easier, resulting in much faster shifting. With the clutch set up you can just about speed shift at WOT. Add a flat shift program with a standalone ECU and shave tenths of a second off every shift.

You will need to reduce pedal travel by about 1" by either adjusting the factory pedal stops, clutch master cylinder pushrod or adding a hard pedal stop. The single disc kits include a spacer block for the throwout bearing.

Details:

• CNC aluminum one piece clutch cover
• Heat treated steel diaphragm springs
• 12.9 rated hardware throughout
• One piece net forged 4140 steel flywheel
• Includes throwout & pilot bearing, pilot tool
• Fits all year Miata 90-05, 1.6 and 1.8 engines

 

iron disc assembly, bearing and tool kit.