ACT 2004 Mazda RX-8 Flywheel Kit Streetlite w/CW03
If you are replacing the clutch in a Mazda RX-8 and want the Renesis to pick up revs faster without turning the car into a rattling track toy, ACT 600145-03 is the flywheel side of that job. It pairs ACT's XACT Streetlite chromoly flywheel with the CW03 counterweight the rotary needs, plus the bolts for both, so you are not hunting for parts once the transmission is out.
The flywheel carries the clutch friction face and the starter ring gear, but on a rotary it also forms part of the rear balance of the eccentric shaft. That is why ACT says the counterweight is required whenever an XACT flywheel goes on an RX-7 or RX-8, and why this kit ships with CW03. ACT states the flywheel is externally balanced for the manual-shift engine using the factory front counterweight, so the front of the engine stays as Mazda built it.
The Streetlite is forged chromoly, CNC machined and dynamically balanced, with an induction-hardened 125-tooth ring gear and a 240 mm (9.4 in) friction surface. ACT lists it at 18.8 lb and certifies it to SFI 1.1. It is the heavier, more durable of ACT's two RX-8 flywheels: ACT describes the feel as noticeably better response with OE to mild gear rattle, and recommends it for street and drag use. The lighter 600140-03 Prolite kit trades more rattle and drivability for even quicker revs and suits road course cars better.
Most flywheel faults only show once the transmission is down, so plan the inspection with the clutch job. Look for heat checking, hard spots and cracks on the friction face and check the ring gear. If the complaint is slipping, rule out an oil leak onto the disc and the clutch hydraulics before blaming the flywheel. Our slipping diagnosis guide walks through separating a worn clutch from other causes, and automatic vs manual repair cost helps you budget the whole job.
Our listing names the 2004 Mazda RX-8. ACT's fitment table for 600145-03 covers the RX-8 with the 1.3L rotary from 2004 through 2011, including Base, Shinka, GS, GT, Sport, Touring, Grand Touring, R3 and 40th Anniversary trims. This kit is the CW03 version for the RX-8; the FD RX-7 uses a different counterweight, sold with our 600145-02 kit. If the car has been swapped or you are unsure what is in it, send us the year and VIN before you order.
| Brand | ACT |
| Part number | 600145-03 |
| Fits | ACT 2004 Mazda RX-8 Flywheel Kit Streetlite w/CW03 |
| Vehicle fitment | Mazda Rx-8 (2004) |
| Type | Flywheels |
| Condition | New |
| Ships | Same business day (in stock), from the USA |
| Warranty | 1-year |
ACT lists 2004 through 2011 RX-8s with the 1.3L rotary, across all trims. Send us your VIN if the car has a swap.
Yes. The kit is the 600145 Streetlite flywheel plus the CW03 counterweight, with flywheel and counterweight bolts.
ACT lists it at 18.8 lb. It is the heavier, more street-friendly of ACT's two RX-8 flywheel kits.
Streetlite. ACT rates it OE to mild gear rattle and recommends it for street and drag use. The Prolite is lighter but noisier and aimed at road racing.
ACT's clutch kits for the RX-8 call for the ACT counterweight with an ACT flywheel. Pair it with an ACT RX-8 clutch kit and check the step if you plan another brand.
Yes. ACT says remove only enough to clean the surface, never more than 0.040 in, and maintain the flywheel step.
