Clutch Masters 93-98 Nissan Skyline RB25DET Eng. (Japan Motor & Trans) Aluminum Flywheel
The Clutch Masters FW-620S-AL is a 13 lb billet aluminum flywheel for the 1993-1998 Nissan Skyline R33 with the RB25DET turbo inline six and its original Japanese-market engine and five-speed. It is aimed at the owner rebuilding the clutch on an imported R33 GTS-T, building an RB25 for drift or time attack, or chasing quicker spool between shifts, and at anyone whose stock flywheel came out heat checked or worn past a safe resurface.
A flywheel is the clamping surface for the clutch disc, the carrier for the starter ring gear and a large share of the rotating mass behind the crank. Clutch Masters machines this one from 6061 billet aluminum, hard anodizes it and zero balances it, and the disc runs on a replaceable steel friction insert rather than on the aluminum itself. When the insert wears, it can be replaced instead of machining the whole flywheel. Less rotating mass lets the RB25 rev up and fall back faster, which Clutch Masters notes helps reduce turbo lag between gears and makes rev-matched downshifts and clutch kicks easier to time. The trade is a little less momentum leaving a stop and more gear rattle at idle. Clutch Masters lists a 13.0 lb weight and SFI 1.2 certification for motorsport use. If you would rather run steel, the Competition Clutch 2-630T-ST 12 lb steel flywheel is built for push-style RB20 and RB25 clutches, and our lightweight vs stock flywheel guide lays out the differences.
Slip on an RB25 shows as rpm rising faster than road speed once boost builds in third or fourth. Before blaming the flywheel, bleed and inspect the clutch hydraulics and look for oil from the rear main seal at the bell housing seam, which contaminates any new surface. The road test is in our slipping diagnosis guide, and shift flare vs slip helps rule out other drivetrain faults. With the gearbox out, check the face for flatness and cracks; our resurface vs replace guide helps with the decision.
Our listing is for the 1993-1998 Nissan Skyline R33 with the RB25DET and its Japanese engine and transmission. Clutch Masters' catalog uses the same FW-620S-AL part number for the 1989-1993 R32 RB20DET, the 1989-1994 R32 GT-R and 1993-1998 R33 GT-R RB26DETT, and the 1998-2001 R34 RB25DE and RB25DET, and its detail table lists both push and pull clutch styles. One exception is spelled out: an R34 GT-R with the six-speed pull-style clutch needs a different part, FW-620S-1SF. Because RB engines and gearboxes are swapped constantly, confirm your clutch style and that the engine and gearbox are the original pairing, then send us the chassis code, engine and year so we can check before it ships. Browse more Skyline clutch parts in our rebuild kits and clutch category.
| Brand | Clutch Masters |
| Part number | FW-620S-AL |
| Fits | Clutch Masters 93-98 Nissan Skyline RB25DET Eng. (Japan Motor & Trans) Aluminum Flywheel |
| Vehicle fitment | Nissan Skyline Rb25Det Eng (1993-1998) |
| Type | Flywheels |
| Condition | New |
| Ships | Same business day (in stock), from the USA |
| Warranty | 1-year |
Clutch Masters lists it at 13.0 lb.
Not with the six-speed pull-style clutch. Clutch Masters says that car needs FW-620S-1SF. The R34 RB25DE and RB25DET are listed for FW-620S-AL.
The disc runs on a replaceable steel friction insert, so when it wears you replace the insert instead of machining the aluminum flywheel.
Yes. Clutch Masters says it works with the factory clutch as well as its FX100-FX500 single disc kits. Confirm your clutch is push or pull style before ordering.
Clutch Masters lists it as SFI 1.2 certified for motorsports use.
