After installing the timing gear it was on to the back of the engine to do the oil pump, main seal and then final installation of the flywheel and clutch plates.
Oil Pump
At this stage, you have to remove the flywheel again (which was temporarily installed for measuring endfloat) and so you will have to BLOCK YOUR CRANKSHAFT AGAIN. Again, I used the Cycleworks front bearing carrier tool as a blocker. When the chain tensioner is in place you can only install the bolt into one side of the bearing carrier, but it’s still enough to block the movement of the crankshaft.
With the crankshaft blocked, the flywheel is removed. Then the woodruff key is installed in the back of the camshaft. The oil pump inner and outer rotors are reinstalled with the dimples facing out. At this stage the measurements can be taken to ensure the pump in in spec. These are;
- Clearance between outer rotor and the housing- 0.10-0.17mm
- Clearance between inner rotor and outer – 0.12-0.30mm
- Clearance between inner rotor and the cover 0.026-0.059mm
Once satisfied with the measurements (if they are too large then one or both of the rotors will need to be replaced) then the cover can be replaced with a new seal. The seal is a red rubber ring (replaces an old black version. As you install the cover be sure the seal remains in its groove. A drop of engine oil can help it to stay put. Many people replace the philips head screws with bolts. Something to do with originality made me keep the screws… Or maybe I just didn’t have any bolts. Who really knows…
Main seal
Replacing the rear main seal is a common job. The seal has been redesigned over the years and there is a lot written about this seal on Snowbum’s site (www.bmwmotorcycletech.info). The current version of the seal is a teflon seal and does not require soaking in hot oil like the old versions. The seal should be pre-stretched onto the flywheel for the sealing lip to take the shape and then can be installed dry into the crankcase, taking care not to disturb the outer thrust washer. The seal should be pushed in until it’s flush with the case and a dedicated tool makes this easier. The seal I bought has a felt lining on it which I removed. I applied a thin smear of grease to the teflon before reinstalling the flywheel.
Flywheel and Clutch Assembly
With the new main seal in place, the flywheel can be definitively installed. To do this, make sure the engine is at TDC (timing dots on the crank and cam sprockets facing each other) and install the flywheel with TDC (OT) positioned in the timing window of the case. It helps to heat the flywheel flange where it will receive the back of the crankshaft. Taking care not to disturb the rear thrust washer, the flywheel is installed with new bolts with a very light coat of oil on them. Torque to spec around 42Nm using a flywheel blocking tool.
The clutch plates can be installed in the same order of removal. I applied a smear of moly grease to the tines of the spring plate. The friction plate has a short and a long splined side. The long side should face out towards the gearbox. Use a centering tool to keep the friction plate centred and then tighten down three of the perimeter bolts using long bolts with a spacers. Then install the three other short bolts, remove the three long bolts with spacers and install the last three short bolts. This is essentially a reversal of the removal process.
