Primary Chain Removal Norton Commando
Article by Mark Trotta
The transmission of a Norton Twin consists of primary chain, stator and rotor, engine sprocket, clutch, chainwheel, and chaincase.
This article details how to remove these components, plus how to use the required special tools.
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Clutch
Clutch Removal is covered in a separate article.
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Chainwheel (Clutch Drum)
Chainwheel removal requires a special tool. I purchased mine from The Bonneville Shop in Montana.
After taking off nut and locking tab washer, clutch locking tool (Norton # 06-1015 or equivalent) fits over center hub.
This allows removal of gearbox mainshaft nut.
Clutch hub locking tool in use.
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Alternator Stator and Rotor
The stator is held onto the crankshaft sprocket with three 5/16" fine-thread nuts with washers and spacers.
Behind the stator is the alternator rotor.
You'll need a way to prevent the chain from turning while removing sprocket nut. Here I'm using a universal primary chain locking tool.
The alternator rotor may or may not come off easily. If not, you can try applying equal pressure with two tire levers (or similar) from behind.
Be sure to collect the rotor keyway, collar, and shim.
Pictured above: rotor spacer and alignment shim.
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Engine Sprocket
Removing the crankcase (engine) sprocket requires a puller, Norton 06-4297 or equivalent.
Sprocket Puller
I was able to adapt a universal pulley puller. Hub threads are 5/16 UNF (fine thread).
Bolt length needed for this application was 4-1/2". Be sure that bolts are threaded in at least 1/2" before trying to loosen.
A few turns with a socket and ratchet and BAM! the sprocket popped loose.
It may help to tap the side of the sprocket a few times with a drift and hammer.
Primary chain, engine sprocket, and chainwheel come off together.
Inner cover is retained by three 1/4" UNC bolts with locking plates.
To maintain proper clutch and sprocket alignment, take note of any and all spacers and washers that came off during disassembly.
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Conclusion
Having the proper tools is essential for British motorcycle restoration. In this case, the engine sprocket puller was able to be fabricated, helping to keep the total repair cost down.
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Related Articles:
Norton Commando Build
Clutch Removal
Cylinder Head Removal
Engine Removal
Pinion Gear Removal
Timing Cover Removal and Installation
Cracked Cooling Fin Repair
Norton Commando Upgrades
