The first time I took Project 325 to the drag strip for testing, launching was impossible. With a stock engine, 90-degree weather and 235/40-17 ContiSportContact 2 tires, I could leave the line at 3500 rpm and bog to 2400, or I could leave at 3800 and watch the revs rise to 4300 as the rear wheels gradually caught up to the engine. That moved a lightweight flywheel and heavy-duty clutch up the priority list.
Project 325's stock flywheel weighs 27.2 lb. As always, I sought to trim fat. Reduced vehicle weight improves performance, regardless of rotational factors, but testing with other cars on european car's Dynojet has shown more torque at the wheels in first and second gears with a light flywheel. Every time I have replaced a dual-mass flywheel with a solid, lighter flywheel, driveability has improved. Potential downsides are a tendency to stall off the line and the rattle of gears cushioned only by automatic transmission fluid. I have never had a problem with the former, and the latter is largely addressed by clutch selection.
Nearly every BMW performance supplier has an aluminum flywheel for the E36. Many are private-labeled from one manufacturer. Most use an E36 M3 clutch disc and pressure plate, an upgrade for any lesser E36. However, the solid M3 clutch disc was designed for a dual-mass flywheel and transmits all the crankshaft's torsional vibrations and any driveline shocks straight through to the gears. The most obvious symptom is gear chatter at idle.
I found two alternatives. Rogue Engineering uses a custom-made, sprung-hub disc with M3 dimensions, featuring carbon/aramid friction material on one side, designed to work with Rogue's own 11.5-lb, aluminum flywheel and M3 sport pressure plate. Rogue Engineering's Ben Liaw states that this package will hold up to 600 hp at the wheels, a figure I have yet to see coming from any E36 engine.
UUC Motorwerks' Stage II aluminum flywheel fits all 1992-1999, six-cylinder, 3 Series BMWs and uses the OE, Sachs-manufactured, sprung-hub clutch disc, pressure plate and throwout bearing from a 1991-1993 E34 M5.
UUC Motorwerks' Stage II aluminum flywheel fits all 1992-1999, six-cylinder, 3 Series BMWs
UUC Motorwerks' Stage II flywheel is a little less extreme. It uses the O.E. Sachs clutch package from the 3,800-lb, 310-hp, 1991-93 M5, which used a sprung-hub disc. Larger and beefier than any O.E. E36 clutch, it will handle substantial power increases. The E36 tuning world has settled on 11- to 12-lb flywheels as a good balance for the street. UUC's Stage II flywheel weighs just 8.5 lb, but with the heavier M5 clutch attached, comes out the same as UUC's 11-lb flywheel and an M3 clutch. The made-in-USA, 6061-T6 aluminum, Stage II flywheel's 1050 steel friction surface is replaceable, so an abused or worn system can be serviced without replacing the entire flywheel. BMW factory mounting hardware is included. The UUC Stage II flywheel fits all 1992-99, six-cylinder, 3 Series BMWs. I chose it for Project 325. Since the transmission would be out of the car, it was the perfect opportunity to also try UUC's Ultimate Short Shifter.
I again turned to Web-based Import Parts Specialists for stock parts. Its prices to the public are on par with distributor pricing available in Southern California, and the numbers it shows as "list" are well below the local BMW dealer's. Combine that with friendly, knowledgeable and consistently prompt service, and IPS is an all-star among Project 325's supporters. It provided the M5 clutch disc, pressure plate and throwout bearing (they were in stock) as well as the driveshaft guibo and bushing.
I try to do as much of the work as possible on Project 325, but installing the flywheel was one thing I knew I'd be better off letting a pro handle. Watching evosport's Ken Brightwell work on my car is like watching myself, except he's already done everything many times and has more and better equipment. He is careful, thinks about what he's doing and cuts no corners.