Chris, that link helps, thank you.
Kenny Cummings of New York City Norton also did a write up years ago on rebuilding the rear iso in frame, anyone know how to find it?
I looked on his website and could not find it, it was there years ago and now gone as far as I can tell.
Ask, and you will receipt:
This is my method for rebuilding the Norton Commando Rear Isolastics.
I’ve used this method on a number of bikes with great success each time. It can be done without having to remove any major parts of the bike (other than the power take-off socket). The total time involved is about 1 ½ - 2 hours.
Note: this operation will NOT work for the MK III or Norvil type Isolastic setup. These types use a single, long spacer tube with the bushes and buffers bonded to the tube. There's no way in Hell one long piece like that is going to fit through the small space we’re working with here. If the MK III/Norvil setup is what you're going for, these instructions don’t apply and a major teardown of the bike will be necessary.
For the rest of us with bikes born before 1975...All you really need beyond a basic set of tools small bottle-jack, a baby-bottle scrub brush, and a patient helper. Here's how it’s done:
Put the bike on the center stand.
Remove the power take-off socket for better access to the Iso mount.
Remove LH side nut from Rear Iso Stud and pound out through the right side; use a drift to get it all the way out.
Remove gaiters, collars, PTFE washers, end caps, and shims.
Now you will have access to the innards of the Iso between the frame and the Iso mount - not much space, but enough to squeeze the rubber bits by.
Dig out the first rubber bush from the RH side.
Pull out the buffer on the spacer.
Dig out the center bush from the RH side.
Dig out the end bush from the LH side
Pull out the 2nd buffer/spacer
Once everything is out, scrape out any old rubber residue that may have bonded to the Iso tube. A screwdriver works fine. Use a baby-bottle brush with some carb cleaner, dousing the inside of the tube and scrubbing it clean. Wipe out the mount by pulling a rag through and making sure it is totally dry.
Insert a new bush into the edge of the RH side.
Using a drift (a socket works great), push it into the Iso tube so the end of the centerpiece of the bush is just flush with the edge of the Iso tube (flush alignment is IMPORTANT).
Assemble the new gaiter, collar, PTFE washer, and end cap back on the Iso mount on the RH side. (Note: I purchased the Hemmings vernier adjusters from Old Britts, which do not require any shims on either side. If you are using old Norton shimming "technology", I suggest you take note of the shims you initially removed, and replace now with new shims of the same thickness as a starting point).
Pushing the main stud back through as you add new bits will keep everything aligned. Begin driving the stud back through from right to left, through the z-plate and spacer, then into the gaiter/collar/washer/end cap and continuing through the first bush. Have a friend sight through from the left side to tell when the stud has reached the end of the bush and stop there.
Insert a buffer on a spacer from the left side then push the stud through this buffer/spacer.
Insert from the left the center bush, then push the stud.
Insert the 2nd buffer/spacer, then push the stud.
Finally insert the last bush on the end of the LH side and push the stud flush with the edge of the center of the last bush. (In my case, the RH bush center was poking out of the tube about 1/8" so I needed to do a bit of tapping with various drifts to snug all the components together within the Iso tube.)
Once everything is nice and tight, place the end cap over the LH side, then a PTFE washer, and finally the Hemmings adjuster and gaiter. (Again, if you are using shims, this is the time to add them.)
Tap the stud through this whole lot, through the frame spacer and out through the Z-plate.
Torque both nuts down to 25 foot lbs. and set the gap with a feeler gauge (with the bike off the center stand). Voila!…You’re done. Ain't no big thing! (By the way - my old Iso rubbers were almost turning to powder, and were so oblong-shaped it’s a wonder they did any absorption at all!)
A few things to know:
Always lubricate the rubber bits liberally with a silicone-based lube (not petroleum based).
Use anti-seize on the stud and nuts, as well as the inside of all the bushes and buffers.
A small bottle jack can help when placed under a frame tube. This will jack up the frame to match the engine mount/Iso tube and assist on alignment of the stud through the z-plates, etc.
By tugging on the rider's footrests, the frame can be pulled away from the Iso mount by a few crucial thousandths of an inch, which allows easier insertion of gaiters/collars/etc. Again, this is where an assistant is key!
Hope this helps.