ACT 90-05 Mazda Miata XACT Flywheel Prolite (90-93 Must Use 1.8L Clutch)
Miata owners who autocross, time-attack or road race their NA or NB car usually end up looking at the flywheel once the clutch is due. The ACT 600255 XACT Prolite is ACT's lightest flywheel for the 1990-2005 Mazda Miata at 9.4 lb, forged chromoly with a 225 mm (8.8 in) friction face and 112 ring gear teeth. It is aimed at race use, so read the drivability notes below before choosing it for a daily driver.
The flywheel carries the starter ring gear and gives the clutch disc a friction face, and its rotating mass decides how quickly the small four-cylinder can change rpm. The 1.6L and 1.8L engines make modest torque, so cutting mass lets them rev up between corners and blip cleanly on downshifts. ACT describes the Prolite line as having the lowest inertia in its range, with the best throttle response and acceleration, preferred for road racing and rally. The cost is reduced drivability: pulling away takes more care, and ACT notes mild to moderate gear rattle.
ACT forges and CNC machines the 600255, balances it dynamically and induction-hardens the ring gear. It is one piece, with no separate insert to warp or work loose, and it can be resurfaced like a factory flywheel. It carries SFI 1.1 certification.
Do a high-gear, low-rpm roll-on to check for slip, and look for oil on the bellhousing that could mean a contaminated disc. Our slipping diagnosis guide covers the test. If the stock flywheel still measures in spec, read our lightweight vs. stock flywheel guide first: a Prolite makes most sense for a car that sees track time.
ACT lists the 600255 for 1990-2005 Mazda Miata, covering the 1.6L cars from 1990-1993 and the 1.8L cars from 1994-2005, including the 2004-2005 Mazdaspeed. It is built around the 1.8L clutch, so a 1990-1993 1.6L car must run a 1994-up 1.8L clutch kit with this flywheel, not the original 1.6 clutch. Confirm the clutch kit you plan to use before ordering, or send us your year and VIN. More Miata parts are in our hard parts collection.
Want the same fitment with easier street manners? ACT's heavier XACT Streetlite covers the same cars, and the Competition Clutch 13 lb steel flywheel is another option for 1.8L cars.
| Brand | ACT |
| Part number | 600255 |
| Fits | ACT 90-05 Mazda Miata XACT Flywheel Prolite (90-93 Must Use 1.8L Clutch) |
| Vehicle fitment | Mazda Miata Xact (1990-2005) |
| Type | Flywheels |
| Condition | New |
| Ships | Same business day (in stock), from the USA |
| Warranty | 1-year |
No. ACT requires a 1.8L clutch with the 600255, so 1990-1993 1.6L cars must use a 1994-up 1.8L clutch kit with it.
ACT lists it at 9.4 lb. It is the lightest of ACT's XACT flywheels for this car.
ACT recommends it for race use. It gives the quickest rev response but has reduced drivability and some gear rattle. Most daily-driven cars are happier with the heavier Streetlite version.
Yes, ACT's application list includes the 2004-2005 Mazdaspeed Miata along with the base, LS and SE 1.8L cars.
Yes. It is one-piece chromoly with no insert, so it can be machined like a factory flywheel when the face wears.
