ACT 2006 Mazda MX-5 Miata HD/Perf Street Sprung Clutch Kit
The ACT ZM4-HDSS is a street clutch for the six-speed NC Mazda MX-5 Miata, the 2006-2015 cars with the 2.0L MZR engine. It is the kit most six-speed owners pick when the factory clutch is worn out and the car has an intake, header, tune or a mild boost kit, and they still want a pedal that works in traffic. If your six-speed NC slips on a fourth-gear pull, engages right at the top of the pedal or shudders pulling away, this is a sensible replacement that adds headroom without turning the car into a race car.
In the NC the clutch sits between the rear of the front-mounted MZR four-cylinder and the transmission, with the input shaft nose riding in a pilot bearing in the crankshaft. ACT's MZ032 Heavy Duty pressure plate uses a stiffer diaphragm, heat treated in four stages, to raise clamp load and reduce deflection. The 3000216 Performance Street disc is a 224 mm (8.8 in) organic disc with a high copper content for heat transfer, a steel backing for burst strength and a sprung hub to soak up driveline shock.
ACT rates the kit at 281 ft-lb at the crank, 34 percent more than the OE clutch, and describes the feel as light to moderate pedal effort with smooth, positive engagement. Because it is organic, it tolerates the slipping that comes with hill starts and stop-and-go driving far better than a pad-type race disc. ACT expects a Heavy Duty plate to add roughly 15 to 40 percent pedal effort depending on the car.
The NC was sold with a five-speed and a six-speed, and the two do not share a disc. ACT specifies ZM4-HDSS for six-speed applications only and lists a 1 in input shaft, while the five-speed street kit, the ACT ZM5-HDSS, uses a different disc and alignment tool on a 0.9375 in input. Count the forward gears on the shift knob before you order.
Look at the hydraulics before blaming the disc. Check the fluid level and color, look for leaks at the slave cylinder and make sure the pedal returns fully, because a release system that drags or never fully lets go causes grinding and heat that look like a failing clutch. To test for slip, make a full-throttle pull in fourth from low rpm and watch whether the tach climbs faster than the speedometer. Our slipping diagnosis guide covers that test step by step, and the manual vs automatic repair cost guide helps you budget the labor.
Our listing names the 2006 MX-5 Miata. ACT's application chart lists ZM4-HDSS for six-speed NC cars from 2006 through 2015, including Touring, Grand Touring, GT, Club, Special Edition and 25th Anniversary trims, plus the GS and GX trims sold in Canada, all with the 2.0L engine. Trim names and gearboxes overlap across years, so confirm the six-speed or send us your year and VIN and we will check it. More clutch parts are in our rebuild kits collection.
If the car makes serious boosted power or sees regular track use, the ceramic ACT ZM4-HDG6 uses the same pressure plate with a 6-pad race disc.
| Brand | ACT |
| Part number | ZM4-HDSS |
| Fits | ACT 2006 Mazda MX-5 Miata HD/Perf Street Sprung Clutch Kit |
| Vehicle fitment | Mazda Mx-5 Miata Hd/Perf (2006) |
| Type | Clutch Kits - Single |
| Condition | New |
| Ships | Same business day (in stock), from the USA |
| Warranty | 1-year |
No. ACT lists ZM4-HDSS for six-speed applications only. The five-speed NC uses the ZM5-HDSS, which has a different disc and input spline size.
ACT lists it for six-speed 2006-2015 Mazda MX-5 Miata NC models with the 2.0L engine, across Touring, Grand Touring, GT, Club, Special Edition and other trims. Send us your year and VIN if you are unsure which gearbox you have.
Yes. It uses an organic disc that ACT describes as smooth and positive, with light to moderate pedal effort. It is the street choice in ACT's NC range.
ACT rates ZM4-HDSS at 281 ft-lb measured at the crank, 34 percent more than the OE clutch. That covers naturally aspirated builds and many mild boost setups.
It includes the pilot bearing, release bearing, alignment tool and pressure plate bolts, but no flywheel. Resurface the factory flywheel or fit a replacement such as the ACT 601140.
ACT recommends 300-500 miles of mild engagement, such as normal city driving, before hard launches or track use. Avoid overheating it during that time.
