ACT 1991 Mazda Miata HD/Perf Street Sprung Clutch Kit
ACT ZM2-HDSS is the everyday upgrade clutch for the first two generations of Mazda Miata. It is aimed at the NA or NB owner whose original clutch is worn out, slipping in the higher gears, or starting to feel vague, and who wants a little more holding power for an intake, exhaust, tune or the occasional autocross without making the car hard to drive in traffic. It uses ACT's most popular Heavy Duty pressure plate with its most popular organic street disc, and ACT rates it at 245 ft-lb.
The Miata's four-cylinder sits lengthwise, so the clutch bolts to a flywheel at the back of the engine and drives the rear-drive gearbox through a hydraulic release: master cylinder, slave cylinder, fork and bearing. ZM2-HDSS clamps a 224 mm (8.8 in) disc with an MZ012 Heavy Duty plate. That plate's diaphragm adds clamp load and resists deflection, while the 3000203 disc keeps a full organic facing with high copper content and a steel-backed lining. ACT's specification sheet:
For most naturally aspirated Miatas, 36 percent over stock is plenty, and the pedal stays close to factory. Turbo and supercharged cars usually need more: the ZM2-XTSS keeps an organic disc with the stronger Xtreme plate, and the ZM2-HDG6 swaps to six ceramic pads for track heat.
Start with the hydraulics, because a weak Miata slave or master cylinder causes many of the same complaints as a worn disc. Check for fluid at the slave and on the firewall behind the pedal, and bleed the system. Then test for slip in a high gear at low rpm with full throttle. Our slipping diagnosis guide explains the test, and the Miata clutch replacement cost by generation page shows what to budget for the job.
We list this kit as a 1991, but ACT's chart covers the NA and NB Miata from 1990 through 2005: the 1990-1993 1.6L cars and the 1994-2005 1.8L cars, including the 10th Anniversary and the 2004-2005 Mazdaspeed. It is not for the 2006-up NC or later models. On the 1.6L cars, check the flywheel before ordering. Those cars came with a smaller clutch, and our ACT Miata flywheel listings say 1990-1993 cars must use them with the 1.8L-size clutch, so a 1.6L car with its original flywheel may need one to match this 224 mm kit. Send us the year and VIN if you are not sure. More Miata clutch parts are in our rebuild kits collection.
| Brand | ACT |
| Part number | ZM2-HDSS |
| Fits | ACT 1991 Mazda Miata HD/Perf Street Sprung Clutch Kit |
| Vehicle fitment | Mazda Miata Hd/Perf (1991) |
| Type | Clutch Kits - Single |
| Condition | New |
| Ships | Same business day (in stock), from the USA |
| Warranty | 1-year |
Yes. ACT lists it for every 1990-2005 Miata with the 1.6L or 1.8L engine, including the Mazdaspeed. It does not fit the 2006-up NC.
ACT lists those years, but the early cars came with a smaller clutch. Our ACT Miata flywheel listings say 1990-1993 cars must use the 1.8L-size clutch with them, so confirm your flywheel or send us your VIN first.
ACT rates it at 245 ft-lb at the crank, 36 percent over the factory clutch. That covers most naturally aspirated and lightly modified cars; turbo builds usually step up to the XT plate.
Only a little. ACT lists light to moderate pedal effort, and its FAQ puts Heavy Duty plates at about 15 to 40 percent more effort than stock depending on the car.
Resurface or replace the flywheel, and replace a tired clutch master and slave cylinder. The release bearing, pilot bearing and alignment tool are in the kit.
ACT recommends 300 to 500 miles of mild engagement such as city driving before racing or spirited driving.
