ACT 01-06 BMW M3 E46 XACT Flywheel Prolite
The ACT 601015 XACT Prolite is a one-piece lightweight flywheel for the 2001 to 2006 BMW M3 (E46) with the 3.2L S54 straight-six. It is a single-mass conversion that replaces the heavy factory dual-mass flywheel. M3 owners shop for it for two reasons: the original dual-mass unit has started to rattle, clunk or shudder, or they are building a track car and want the S54 to rev and fall as quickly as possible between shifts.
The flywheel bolts to the crankshaft, carries the starter ring gear and provides the rear friction surface for the clutch disc. ACT forges the 601015 from chromoly steel, CNC machines it and computer balances it. It weighs 9.9 lb, with a 240 mm (9.4 in) friction surface and an induction-hardened 113-tooth ring gear, and it carries an SFI 1.1 rating. Prolite is ACT's lowest-inertia flywheel line, built for the best throttle response and acceleration.
That low inertia is the whole point and also the catch. ACT recommends the Prolite for race use and says drivability is reduced: expect mild to moderate gear rattle at idle and more care needed pulling away from a stop. Owners who want a lighter flywheel on a street-driven M3 should look at the heavier 601010 Streetlite instead, which ACT rates as its most durable flywheel.
Because the 601015 is solid, there are no internal springs or friction rings to wear, and it can be resurfaced at the next clutch job like an old-school flywheel. ACT limits resurfacing to 0.040 in (1.02 mm) of material and requires that the original step be kept.
A failing dual-mass flywheel is often mistaken for valvetrain or gearbox noise. Listen at the bellhousing while you press and release the pedal at idle; a change in the noise points toward the flywheel or release bearing. With the transmission out, rock the two halves of the dual-mass unit against each other and look for excessive free play, then inspect the friction surface. If your real complaint is slip rather than noise, read our slipping diagnosis guide first, because a worn disc alone does not call for a new flywheel.
ACT lists the 601015 for the 2001 through 2006 BMW M3 E46 with the S54 3.2L, including Euro-market cars. It does not fit the 325i, 328i or 330i, which use different engines and clutches. ACT states it works with both the factory clutch and ACT clutch kits, and the flywheel bolts are included (M12-1.5 x 30 mm). If your car has SMG or has been converted between transmissions, send us the VIN and we will confirm before it ships. For more parts, see our hard parts category.
| Brand | ACT |
| Part number | 601015 |
| Fits | ACT 01-06 BMW M3 E46 XACT Flywheel Prolite |
| Vehicle fitment | BMW M3 E46 Xact (2001-2006) |
| Type | Flywheels |
| Condition | New |
| Ships | Same business day (in stock), from the USA |
| Warranty | 1-year |
ACT lists the 601015 Prolite at 9.9 lb. The 601010 Streetlite for the same car is 15.1 lb.
Yes. ACT states the 601015 can be used with both the factory clutch kit and ACT clutch kits. Expect more gear rattle than with the original dual-mass flywheel.
ACT recommends the Prolite for race use and notes reduced drivability. For a street car, the 601010 Streetlite keeps more inertia and is easier to drive in traffic.
Yes. ACT includes M12-1.5 x 30 mm flywheel bolts with the 601015.
Yes. ACT says XACT flywheels resurface like a stock flywheel. Remove no more than 0.040 in (1.02 mm) and keep the correct step.
