MKIII swingarm

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Swingarm will fit, but the pinning for the spindle is different, you have to use the old style spindle & bolt.

Mark III swingarm has no lower locating provision for the drum brake torque lug, and no threaded bosses for the chain adjusters.
 
But it would be a great opportunity to put a rear disc on the 71
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If you are going with the stock MkIII rear disc, then don't bother. Been there done that. It is more headache and adds more unsprung weight than improved braking. After I converted to an aluminum caliper mount, a Brembo caliper, Brembo disc, and Brembo master cylinder it pared off the extra weight and gave a controllable, progressive brake. (What else can you ask of a rear brake?).

Use the swingarm and maybe the hub, but re-engineer the rest. You'll be glad you did.
 
Thanks for the replies. Just purchased a 71 Commando with a 75 engine and tranny. The swingarm is 71 with a Norton disc setup. Planning on replacing the stock front end (drum) with either a Norton disc or a dual disc FXRS front that I have. Am going to update 71 frame with later sidestand mount and rear shock tower bracing - unless I can find a MKIII frame. Would like to get a MKIII swingarm for the sealed bushing aspect. Cooper
 
gcooperlll said:
Thanks for the replies. Just purchased a 71 Commando with a 75 engine and tranny. The swingarm is 71 with a Norton disc setup.
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If it has a disk it might be MkIII already. Pictures please?

Planning on replacing the stock front end (drum) with either a Norton disc or a dual disc FXRS front that I have. Am going to update 71 frame with later sidestand mount and rear shock tower bracing - unless I can find a MKIII frame. Would like to get a MKIII swingarm for the sealed bushing aspect. Cooper
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The sealed bushing is not a reason to upgrade to the MkIII swingarm.
 
Only advantage in 850 swing are is the front V boxed bracing which is only noticed if riding like everyone complains I over do and do indeed, at times.
The earliest 850 swing arms are direct replacement for drum brake 750's.
A high side under full power can bend either type swing factory arms.

hobot
 
Only advantage in 850 swing are is the front V boxed bracing which is only noticed if riding like everyone complains I over do and do indeed, at times.
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Hobot,
The MkII is even stronger than the '73-'74 arm! Noticeably thicker tube. So if you like the boxed brace 850 drum arm, you would love the MkIII. Of course it is proportionately heavier (sorry Ludwig :( ).
 
Ok thanks for more Cdo education Ludwig. A flexy swing arm could sure add to the Hinge effect. Its always good to know what can mix-match in Cdo's.
I"m not up on the MK designations, so hard to follow the versions. I'm strictly a Combat man, prior models are just the built up to it and later models after is just the let down from that peak to me. My experiments conclude its plain foolish to find out what can cause the swing arm to matter in un-rear-linked Commandos. Low tire air practice can reveal this w/o go to jail speed risks. I learned to get away with riding into and out of THE Hinge on tarmac d/t its onset at way lower loads and speeds on THE Gravel and of course flats at either end. Up grade swing arm is fine idea but the real Commando limiter is lurking un-tamed.
Best swing arm upgrade to me is real grease zerts.
 
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