Her's a copy of that old info:
From: Michael Taglieri <miket--nyc@j...>
Date: Sat Mar 12, 2005 10:46 pm
Subject: Machining Speedo Drive for Commando Solid-Rear-Axle Conversion
Awhile back I mentioned that the bearings in the rear axle of the Norton
Commando have an internal diameter of 17mm, and the various spacers are
there to "convert" them down to the 9/16" rear axle, which is not only
two piece, but rather puny for the job. Therefore (inspired by Frank
Forster, who did the same thing on a MKIII), I explained how to drill out
the spacers on a lathe, file the slots in the swingarm, and use the 17mm
rear axle from a Honda 350 to turn the Commando into a bike with a
larger, one-piece rear axle that's virtually bombproof. Ben English made
the idea even more attractive by pointing out that you're not limited to
the Honda 350, because just about every Japanese and European bikes from
that era used 17mm rear axles.
I said that the machining involved was child's play for anyone with a
lathe (and perhaps even a drill press if you were careful) -- just drill
out the dummy axle and all the spacers to 17mm. Now I have to take that
back, because there's one part of the job that takes a fair amount of
lathe skill, the speedo drive. The speedo drive on a rear-drum-brake
Commando is centralized on the axle by the little top-hat-shaped insert
that the parts book calls "NM.13270 spacer - Speedomer Gearbox" (that's
how it's spelled). This insert is 9/16" on the inside and 17mm on the
outside, so it slips nicely into the 17mm spacer on the wheel NM.18234
(the only one NOT converted down to 9/16") when you put the speedo drive
on.
To use a stock speedo drive with the 17mm axle conversion, you have to
make a new insert that's 17mm on the INSIDE rather than the OUTSIDE.
Then you bore spacer NM 18234 to fit the larger insert with about .010"
clearance, like the original insert in the original spacer. I made the
new insert .725" OD.
Finally, you remove the felt seal from the speedo drive, tape it on the
inside with masking tape to protect the mechanism from swarf, then set it
up on the faceplate and bore it to take the larger insert. The result of
all this is a speedo drive that accepts the larger axle and centralizes
on the wheel the same way as before.
Sorry if this is incomprehensible, but it was aimed at home-shop
machinists, to whom I hope it's clear enough. (BTW, fooling around with
a lathe is a great hobby for someone with an old bike. I did all this
work on my Chinese 7x10" lathe that costs about $300).
Mike Taglieri miket--nyc@j...
