Exedy 2004-2014 Subaru Impreza WRX STI H4 Lightweight Flywheel
The Exedy FF501A is a lightweight chromoly flywheel for the 2004-2014 Subaru Impreza WRX STI, the turbocharged 2.5-liter flat-four with the six-speed manual. STI owners usually come looking for it in the middle of a clutch job: the old flywheel shows hot spots or cracks, the new clutch judders on takeoff, or the car is being built for autocross, rally or track days and the owner wants the engine to spin up and drop faster between shifts.
The flywheel is the friction face the clutch disc grips, the carrier for the starter ring gear and a large slice of the mass the crankshaft has to accelerate. Taking mass out of it lets the boxer engine rev more freely and fall back faster when you lift, which makes heel-toe downshifts and quick upshifts easier to time and helps the turbo stay in its boost range between gears. Exedy machines its lightweight flywheels from one-piece chromoly steel with the ring gear teeth cut into the flywheel itself, so there is no pressed-on gear that can loosen the way an aluminum flywheel's ring gear can. Exedy says the line is tested to 15,000-18,000 rpm and is SFI approved. The trade-off is normal for any light flywheel: pulling away from a stop takes a little more throttle, and some extra gear rattle at idle is expected. Our lightweight vs stock flywheel guide covers those pros and cons in depth.
Flywheel problems usually show up first as a clutch complaint. On the road, a fourth-gear full-throttle pull that sends the tach ahead of road speed means slip; our slipping diagnosis guide walks through it, and shift flare vs slip helps you rule out other causes. Check the clutch hydraulics and look for oil at the bell housing seam from the rear main seal before blaming parts that cannot be seen. With the six-speed out, inspect the friction face under good light, check every ring gear tooth and measure flatness. Light glazing can be machined; cracks, deep hot spots or a face already cut thin mean replacement. See resurface vs replace.
Our listing covers the 2004-2014 Subaru Impreza WRX STI. Exedy's own catalog lists FF501A for every 2004-2014 WRX STI and also for the 2007-2009 Legacy GT spec.B, which shares the six-speed manual. It is not the flywheel for the five-speed WRX, Legacy GT or Forester XT; Exedy covers the 2006-2014 five-speed WRX with FF502A, and the 2002-2005 2.0L WRX uses different parts. If your car has had a transmission or engine swap, send us the year, VIN and what is installed and we will confirm before it ships. More STI drivetrain parts are in our hard parts collection.
| Brand | Exedy |
| Part number | FF501A |
| Fits | Exedy 2004-2014 Subaru Impreza WRX STI H4 Lightweight Flywheel |
| Vehicle fitment | Subaru Impreza Wrx Sti H4 (2004-2014) |
| Type | Flywheels |
| Condition | New |
| Ships | Same business day (in stock), from the USA |
| Warranty | 1-year |
No. FF501A is for the 2004-2014 WRX STI six-speed and the 2007-2009 Legacy GT spec.B. Exedy lists FF502A for the 2006-2014 five-speed WRX.
Exedy builds its lightweight flywheels from one-piece chromoly steel with the ring gear teeth integrated into the flywheel, not pressed on. Exedy says the line is tested to 15,000-18,000 rpm and is SFI approved.
It replaces the factory flywheel for the STI, so a stock-style STI clutch kit or an Exedy Stage 1 or Stage 2 kit for the same years is the right family. Tell us the kit you plan to run and we will confirm it.
Slightly. Expect quicker revs, a little more throttle needed when pulling away, and some gear rattle at idle. Most owners of tuned STIs find it worth it.
The clutch kit, flywheel bolts, pilot bearing, and the rear main seal if it shows any seepage. Bleed the hydraulics with fresh brake fluid afterward.
