1970 rear brake

This may have been discussed before but I am new to the list and have a question.
I recently purchased a 1970 750 Commando which came in boxes, lots of boxes. Going through it all I noticed that the only rear brake drum I got was the bolt up style instead of the cush-drive type I am used to. I got 2 rear wheels one of each type so that just adds to my confusion. The 69-70 parts book indicates a bolt up type but I can't see any reference to a drive train shock absorber. I plan on using the cush-drive rear wheel but curiosity has the best of me.

The bolt-up hub would be correct for 1970. As you've discovered, this has no drive train shock absorber but it can be replaced with the later cush drive wheel and brake assembly.

The 69/70 rear wheel assembly is pretty much different than 71 on. You can change to a 71 rear wheel assembly, but a lot of the parts are different. I suppose it depends on which parts you have. There's a 69/70 parts book available that shows all the parts.

Dave
69S

Suggest you check the 9/16" threads on your rear axle, stub axle, and nut.
If you are pulling mixed parts from boxes they could have different years.
There was a change from 20 to 18 threads per inch somewhere in this period.

I'd suggest getting the single piece rear axle from madass. It's actually 3 pieces, the axle, the spacer and the nut. Comes for the 68/70 bikes and also the 71 up.

Thank you all for your input.
It looks like this project will take some time to sort out. The good thing is I have the time and it keeps busy.
Who is madass and how do I contact him?

Search Madass and profile. A sweet 70 as Dog T. Knows , should run the fixed cushion-less rear wheel and axle. But for sure $pend the money on his system unless you are nit- pickety for authenticity sake. Or fit the later cush -drive type. Note axles are threaded differently about then . So pick through the boxes for correct axel threads. :|

While you have the parts on the bench, learn how to remove the double row ball bearing from the sprocket.
This bearing is almost always trashed due to no maintenance.
There are modern bearing upgrades available.

That double row bearing is usually toast . Pile o' boxes neglected for greasings, Sealed modern yes. Not cheap.

Several people sell the correct double row bearing, front is the same, just on the other side. Walridge for one, although some say the bearing is not up to the job, but I haven't had any problems. It was ~$30 5 years ago, probably more like $50 now. Better than machining the hub IMO.

You can get the 68/70 parts book here http://www.eurooldtimers.com/eng/manual ... 1970-.html It's got a good diagram of the front and rear wheel, but you have to blow it up. Make sure to follow the workshop manual procedure to get the bearings out and in.

Since Madass has already been mentioned you might consider his newly run up big cush drive rear with SS axle. It isn't cheap but the standard
Norton cush drive is a quick short term fix. Take a hit now and be done with it forever.

I have the 69-70 parts book. So that is covered.
I will be using the later type of rear cush - drive and have most but not all the rear brake parts in my stash of stuff. Already dug out a later swing arm and plan on doing the MK3 cotter style swing arm lock on the cradle.

More about me....
I have been riding my Commando since 1976 and have about 250K on it. I say about 250K because of the number of speedometers I have gone through, the first one died at 97K.
I know what I don't know about Norton's is a lot. Small changes that were made and people like Jim Comstock who help us make our bikes better. I try and buy used and abused Norton's to save them if I have the time and money to do so. That drives my wife crazy but it's a gift I share!
Plan on being at Lake of the Pines next month, cheers