Competition Clutch 1989-2002 Nissan Skyline RB20/RB25 12lb Steel Flywheel

Competition Clutch 2-630T-ST is a 12 lb one-piece steel flywheel for the 1989-2002 Nissan Skyline with an RB20 or RB25 inline six, the R32, R33 and R34 GTS-T style cars and the many JDM RB swaps built around them. Buyers usually land here for one of three reasons: the factory flywheel is heat checked or worn past resurfacing, a new clutch is going in and the owner wants the engine to rev and drop faster between shifts, or a drift or track car needs a flywheel that will not come apart at high rpm.

What a lightweight flywheel does on an RB20 or RB25

The flywheel is the friction surface the clutch disc clamps against, the carrier for the starter ring gear, and a big share of the rotating mass the crank has to speed up and slow down. Taking weight out lets the engine climb through the rev range quicker and fall back faster when you lift, which makes rev-matched downshifts and clutch kicks easier to time. Competition Clutch machines this part from 4140 forged steel as a single piece, so there is no separate insert or bolted friction plate, and it rates the finished weight at 12.00 lb. The trade-off with any light flywheel is a little less momentum at takeoff and on hills, so you use slightly more throttle leaving a stop. Competition Clutch positions the ST series as the street-friendly balance; the 10.4 lb 2-630T-STU ultra lightweight version goes further for track-first cars. Our lightweight vs stock flywheel guide walks through the trade-offs in more detail.

Symptoms that mean the flywheel needs attention

• Clutch slip under boost even after a new disc, often from a glazed or heat-spotted flywheel face
• Chatter or judder pulling away in first or reverse
• Blue heat marks, cracks or deep grooves on the friction surface when the transmission is out
• Starter grinding or skipping teeth on a damaged ring gear
• A flywheel that has already been cut close to its minimum thickness

How to confirm before you buy

A slipping RB shows engine rpm rising faster than road speed in third or fourth as boost comes in. Before blaming the flywheel, check the clutch hydraulics and look for oil at the bellhousing seam from the rear main seal, which will contaminate any new surface. Our slipping diagnosis guide covers the road test, and shift flare vs slip helps separate a clutch problem from other drivetrain noise. With the gearbox out, a straightedge and feeler gauge tell you whether the old flywheel is flat; if it is cracked or near minimum thickness, see resurface vs replace.

Fitment

Competition Clutch lists 2-630T-ST for 1989-2002 Nissan Skyline RB20 and RB25 applications, covering R32, R33 and R34 chassis and RB20DE, RB20DET, RB25DE and RB25DET engines, including JDM engine swaps. Its spec sheet carries one important note: this flywheel is for a push style clutch. Confirm your car or swap uses the push-type release arrangement and the stock RB bolt pattern before ordering. It is not the part for the RB26DETT GT-R twin plate setup. Because Skyline drivetrains get mixed and matched in swaps, send us the chassis code, engine and gearbox and we will check it against the catalog before it ships.

Install notes

• Clean the friction face with brake cleaner to remove the protective coating before the clutch goes on.
• Use new flywheel bolts with thread locker and torque them in a crisscross pattern to the factory RB figure.
• Replace the pilot bearing in the crank while it is exposed; a pilot bearing puller makes the old one come out cleanly.
• Competition Clutch matches this flywheel to Gravity, Stage 1 and Stage 2 kits. A push-type kit such as the SPEC SN233H Stage 2+ RB kit pairs well for a tuned street car.
• Check the rear main seal and replace it if there is any seepage, then bleed the clutch with fresh brake fluid.
• Bed the new clutch in gently for the first few hundred miles before hard launches.

Does 2-630T-ST fit an RB26 GT-R?

No. Competition Clutch lists it for RB20 and RB25 Skyline applications with a push style clutch. RB26DETT GT-R twin plate setups use different parts.

How much does it weigh?

Competition Clutch rates it at 12.00 lb. The 2-630T-STU ultra lightweight version for the same engines is 10.4 lb.

Which clutch should I run with it?

Competition Clutch matches this flywheel to its Gravity, Stage 1 and Stage 2 kits. Any push-type RB20/RB25 kit built for a single mass flywheel is the right family; tell us the kit you plan to use and we will confirm it.

Will it make the car harder to drive on the street?

It is the street-oriented weight in the range. Expect quicker revs and slightly more throttle needed to pull away cleanly, especially on hills.

What else should I replace while the gearbox is out?

New flywheel bolts, the pilot bearing, the rear main seal if it weeps, and fresh brake fluid in the clutch hydraulics.

• Transmission Slipping Diagnosis Guide
• Shift Flare vs. Slip: How to Tell Them Apart
• Automatic vs. Manual Transmission Repair Cost