ACT 2007 Mazda 3 HD/Perf Street Sprung Clutch Kit
Most Mazdaspeed3 and Mazdaspeed6 owners looking at this kit have the same story: the car got a tune, an intake or a bigger turbo, and now the clutch slips in the upper gears at peak boost. The ACT ZX4-HDSS is ACT's Heavy Duty pressure plate paired with its Performance Street organic disc and the lightweight XACT Prolite flywheel. It is the smoothest, most street-friendly of ACT's Prolite kits for these cars. Our listing title says 2007 Mazda 3, but this is a Mazdaspeed part, not a fit for the regular non-turbo Mazda3.
The 2.3L DISI turbo four makes a lot of midrange torque, and the factory clutch has little margin once boost goes up. ACT rates ZX4-HDSS at 449 ft-lb at the crank, 51 percent over the stock clutch. The MZ031 Heavy Duty plate raises clamp load through ACT's diaphragm design, and the 240 mm sprung organic disc (3000215) uses high-copper friction material for heat transfer with a steel-backed lining for burst strength. ACT describes the feel as light to moderate pedal effort, smooth positive engagement and OE to mild gear rattle. The 600521 Prolite flywheel is the lighter of ACT's two Mazdaspeed flywheels, so revs rise and fall quicker between shifts.
Test in 4th gear from low rpm with full throttle and see whether engine speed outruns the car. If it does, check the hydraulics: a tired slave cylinder or a pedal that does not return fully can leave the clutch partly released. Also look for rear main or input seal oil, which will ruin a new disc. The Mazdaspeed3 clutch upgrade guide covers the common failure pattern, and our slipping diagnosis guide helps rule out other causes.
ZX4 kits use the Prolite flywheel; ZX5 kits use the heavier Streetlite. If you want a little more flywheel mass for easier pull-aways in traffic, the ZX5-HDSS uses the same plate and disc on the Streetlite. If the car makes more than 449 ft-lb or sees track use, the ZX4-HDG6 swaps in a sprung 6-pad race disc on this same flywheel, with more aggressive engagement.
ACT lists ZX4-HDSS for the 2007-2013 Mazdaspeed3 and the 2006-2007 Mazdaspeed6, all with the 2.3L turbo and six-speed manual. The input shaft diameter is 1 in. It does not fit the naturally aspirated Mazda3 or Mazda6. Our listing fitment reads 2007 only, but ACT's application covers the full range above. If the car has a swapped gearbox or you are unsure what you have, send us the year and VIN and we will confirm before shipping.
| Brand | ACT |
| Part number | ZX4-HDSS |
| Fits | ACT 2007 Mazda 3 HD/Perf Street Sprung Clutch Kit |
| Vehicle fitment | Mazda 3 Hd/Perf (2007) |
| Type | Clutch Kits - Single |
| Condition | New |
| Ships | Same business day (in stock), from the USA |
| Warranty | 1-year |
No. ACT lists it only for the turbocharged 2007-2013 Mazdaspeed3 and 2006-2007 Mazdaspeed6.
ACT rates it at 449 ft-lb at the crank, 51 percent more than the factory clutch.
Yes. The kit includes ACT's 600521 XACT Prolite flywheel, which is required with the MZ031 pressure plate.
ACT describes it as light to moderate. Its FAQ says Heavy Duty plates typically raise pedal effort 15-40 percent depending on the car.
Same plate and disc. ZX4 has the lighter Prolite flywheel for quicker revs; ZX5 has the heavier Streetlite, which is a little easier in stop-and-go traffic.
ACT recommends 300-500 miles of mild, stop-and-go style driving before hard launches or racing, without overheating the clutch.
