Lightweight Flywheel
(Click images to increase size)Installing a lightweight flywheel is a popular upgrade for track guys. This is a pretty involved job, so I will explain the procedure and provide pictures to help clarify them. I will be using an E36 M3 as the car for this modification.
The transmission will need to be removed and to do that the exhaust system must be removed. This is done by removing the 6 hex nuts at the down pipes. They can be on pretty tight so it may involve heating the nuts up with a torch to get them off. If they are tight and you try to remove them without heating them up you could snap the studs off. If this happens you will have to drill and tap out the studs. This is a lot of extra work, so heat can be a very good friend. After these are removed you will remove the 2 bolts that hold the bracket that connects the transmission to the exhaust. The connector for the oxygen sensor can be unplugged at this time. Next are two bolts that hold the exhaust hangers just behind the cat. And finally the four nuts that hold the rear hangers. Get a friend to help you drop the exhaust and set it to the side. Next the heat shield will need to be removed. The heat shield is held by 4 sheet metal screws. After this is removed and set aside you will be able to drop the forward part of the drive shaft. You will have to remove the three large bolts that hold the flex disc to the transmission output flange and the 2 nuts holding the center support bearing. The forward part of the driveshaft can now be lowered.
After the driveshaft is down it is easier to get to the shifter linkage. Remove the clip that holds the shift tower to the transmission. Remove the clip that holds the shift linkage to the bottom of the shifter. Disconnect the reverse light switch and remove the harness from it’s clips that secure it to the transmission. We are now ready to remove the torx bolts that secure the transmission to the engine. You will need a 10,12 and 14 torx sockets to do this. Using a long extension and swivel with these sockets will be necessary. The starter, held in by 12 mm torx bolts, has a locating pin that may need to be tapped with a punch. It has a tendency to rust thus making removing the starter from the transmission a chore. After all the bolts are removed get a friend to help remove the transmission and set it to the side. Remove the 6mm allen bolts from the pressure plate. Drop the old clutch disc and pressure plate and discard IF you are installing a new clutch assy. While the clutch is out use a special tool to remove the pilot bearing that is pressed in the rear of the crankshaft.
The release bearing in the front of the transmission should be replaced also. At this time check the shift fork that supports the release bearing and the pivot pin for wear, replace as necessary. You will need a 19mm socket to remove the old flywheel. When installing the new lightweight flywheel make sure the steel plate is installed between the bolts and the flywheel. The bolts should be clean and lock-tite should be put on the threads. Using a torque wrench tighten bolts to factory spec. Using an alignment tool install the new clutch disc and pressure plate. The bolts that hold the pressure plate should also be cleaned and lock-tite put on the threads. Also torque to factory spec. I like to tighten using a cross-wise pattern. Install new release bearing on shift fork and apply a small amount of anti-seize on pivot pin and input shaft splines of transmission. It would be a good time to clean the locating pin on the starter and apply ant-seize to the pin. This will make removing the transmission or starter easier later. Now you are ready to reinstall the transmission. Use the directions of removal in reverse to install. Attached are some photos that may help with your install project.
