| Diagram | Fig. 10 — Inner and Outer Chaincase, Hydraulic Tensioner · ref 1 |
| Subsystem | primary |
| Listed in parts books | 1975 |
Norton Chaincase, Inner
Inner primary chaincase for the Norton 850 Commando Mark III, built for the hydraulic chain tensioner setup.
This is the inner chaincase for a Norton Commando, the fixed half of the primary chain enclosure that bolts to the frame and carries the engine sprocket, clutch, and drive chain on its inside face. The outer chaincase seals against it, and on Commando Mark III models with the hydraulic primary chain tensioner, this inner case is part of that setup, as noted in the parts book figure covering the inner and outer chaincase with hydraulic tensioner.
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The catalog places this part on the 850 Commando Mark III specifically. If you're working on an earlier Commando without the hydraulic tensioner, check your existing case before ordering, since the tensioner arrangement changes what mounts inside.
This is a Norton part, not a Triumph part, despite showing up in a numbering scheme that might look unfamiliar. Give us a call if you want to confirm the tensioner-equipped setup matches what's currently on your bike before you order.
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