ACT 1991 Mazda Miata HD/Race Sprung 6 Pad Clutch Kit
NA and NB Miata owners who road race, autocross or run a mild turbo often hit the same wall: a stock or organic street clutch that glazes, fades or starts to slip after a few hard sessions. ACT ZM2-HDG6 combines ACT's Heavy Duty pressure plate with a 6-pad, spring-centered ceramic disc. It is aimed at the car that needs heat resistance and quick, positive engagement, while keeping the pedal lighter than ACT's Xtreme pressure plate option.
The Miata's clutch bolts to a flywheel on the back of the B-series four-cylinder and drives the five- or six-speed gearbox through a single disc. ACT rates ZM2-HDG6 at 310 ft-lb of torque capacity measured at the crank, 74 percent above the factory clutch. The disc is 8.8 in (224 mm) with ceramic pads, on a 0.9375 in input shaft.
ACT's Heavy Duty diaphragm raises clamp load and limits deflection, and the spring center in the disc damps torsional vibration so the hub survives hard use. Because the disc has six separate pads instead of a full face, it bites hard and shifts quickly, and the ceramic friction tolerates the heat of repeated track laps. ACT rates the feel as light to moderate pedal effort with aggressive engagement and OE to mild gear rattle, with moderate friction life. ACT's own figure for Heavy Duty plates is a 15 to 40 percent rise in pedal effort, much less than the 50 to 80 percent it quotes for Xtreme.
Confirm the slip with a high-gear, low-rpm full-throttle pull: if the tach outruns the road speed, the disc is done. Then rule out the hydraulics, because a worn master or slave cylinder causes dragging and grinding that feels like a clutch problem. Our slipping diagnosis guide explains the road test, and shift flare versus slip helps separate the two.
Choosing between ACT's Miata kits comes down to use. A mostly street car is better served by the HD Perf Street sprung kit, which keeps a full-face street disc. A high-boost car that needs more than 310 ft-lb should look at the XT Race sprung 6-pad kit, accepting a heavier pedal.
The listing title names 1991, but ACT applies ZM2-HDG6 to the whole first two Miata generations: 1990-1993 1.6L cars and 1994-2005 1.8L cars, including special editions and the 2004-2005 Mazdaspeed Miata. It is not for the 2006-up NC or later cars. Early 1.6L cars originally used a smaller clutch, and ACT's flywheels for these cars specify the 1994-up 1.8L-size clutch, so a 1990-1993 owner should plan on a matching 1.8L-pattern flywheel and talk to us before ordering. Confirm part number ZM2-HDG6 on the box and send the year and VIN if you are unsure what is in your car.
The flywheel is sold separately.
| Brand | ACT |
| Part number | ZM2-HDG6 |
| Fits | ACT 1991 Mazda Miata HD/Race Sprung 6 Pad Clutch Kit |
| Vehicle fitment | Mazda Miata Hd/Race Sprung 6 (1991) |
| Type | Clutch Kits - Single |
| Condition | New |
| Ships | Same business day (in stock), from the USA |
| Warranty | 1-year |
Yes. ACT lists ZM2-HDG6 for 1994-2005 1.8L Miatas, including the Mazdaspeed, as well as 1990-1993 1.6L cars. It does not fit the NC or ND.
Both use the same 6-pad sprung race disc. ZM2-HDG6 uses ACT's Heavy Duty plate, rated 310 ft-lb with a lighter pedal; the XT kit uses the Xtreme plate for 405 ft-lb and a heavier pedal.
It can be driven on the street, but ACT describes engagement as aggressive and recommends it for high horsepower street or race use. For a daily driver the HD Perf Street kit is smoother.
At minimum have yours resurfaced. A flywheel is not included. Early 1.6L cars should use a flywheel made for the 1994-up 1.8L clutch size.
MZ012 pressure plate, 6224205 disc, RB813 release bearing, PB1005 pilot bearing and the AT05 alignment tool.
ACT says race discs typically need only a few hard slips to lap in. Do not overheat the clutch during break-in, which can glaze the surfaces.
