BMW e36 318iS lightweight flywheel replacement

I replaced the original dual-mass (2-piece) flywheel on my 1998 BMW 318iS (M44 motor) with a lightweight flywheel from RHD Engineering in Sydney, Australia. My aim was (besides fixing the clutch which was just starting to slip after 240,000km) to improve the gearchange, which felt a little slow with the heavy flywheel.

This video just shows the necessary changes to suit the new thinner, lighter flywheel. The flywheel ring gear is identical so no changes needed to the starter motor. The clutch pressure plate and driven plate is for a M20 six, the clutch release bearing remains the same. The clutch slave cylinder pushrod needs lengthening to suit the further-forward position of the pressure plate due to the thinner flywheel. The flyweel bolts are shorter, and the clutch pressure plate bolts also needed to be shortened very slightly to not bottom out in the holes. Everything else remains the same.

The rest of the steps in removing the clutch and flywheel, and reassembling, I've put in a separate video.

Was it worth it? Since the clutch was due for replacement, yes. It is recommended to replace the dual-mass flywheel at the same time. The lightweight competition flywheel plus standard M20 clutch was cheaper than a new dual-mass flywheel and clutch. There are one-piece (non-lightweight) flywheel and clutch kits available cheaper.

The difference was discernible, not as dramatic as a comparison of flywheel weights would suggest, since the crankshaft remains the same. The gearchange now feels 'normal' rather than 'slow' as it did before. There is a little more engine vibration, though not obtrusive, no more than other cars, when pulling from low revs, but then I don't do that often.

Weights:
Old flywheel (dual-mass) 12.1kg New flywheel 3.2kg
Clutch pressure plate 4.0kg New 5.2kg
Clutch driven plate 0.8kg New 1.2kg

Clutch diameter (driven plate) 216mm New 232mm

Flywheel bolt length (old) 50mm New 26mm**

Clutch bolt length 16mm New 15mm**

Slave cylinder pushrod 89mm New 104mm**

** Check this on your installation!