Norton Commando Adjusting Isolastics keeping all units in line when fitting Norvil Headsteady. 

Hi Damian, I'm afraid I really don.t know. I only ever replaced mine both times I did such a thing, at the same time I was replacing or having the frame painted. At a guess I would imagine that if you removed the exhausts, the back wheel, maybe the back mudguard, the front isolastic and the top Isolastic, that upon removing the rear Iso bolt, the whole engine assembly still in the cradle would have space to come forward or twist forward enough to give access, maybe the battery carrier and oil tank would also need to come off. Obviously use some blankets etc to prevent the engine scratching the frame.If you are on Facebook, join the Norton Commando group and ask there.

@Peter Charlton cheers Peter , I'm Not too fussed about scratches as the bike has its fair share of wear and tear, I bought it as a non runner/project so while the head is away being reconditioned I thought I'd look at the Isolasatics, both are knackered so need doing , it's going back together in mechanically refurbished state, I want to see if I actually like the thing before blowing a fortune making it look shiny and pretty, did that before with an A65 and hated it .

@@damiantuttle1348 With the head off, I would guess there will be a ton of room to pivot the engine forward enough to get at the rear Isolastics, I forgot to say you need to remove the shocks as well. A good Commando is maybe the best bike in the world, Keanu Reeves could have any bike he wanted and you will always see him on one of his Commandos.

you don't need to remove the engine and gearbox to replace front and rear isolastics, I recently did mine successfully, there is info on it online, I changed mine to vernier at the same time.

I'm not familiar with Mick Hemmings Isolastics so would be guessing to say it is the cradle tube ends itself that they adjusters rest against, so cannot see how the iso rubbers could be to blame unless their internal tubes are protruding further than the cradle tube and associated parts before the adjusters themselves. After ascertaining the iso rubber location in not at fault, here is what I would do, and did on mine. I removed the front collets and shims and hung the front of the engine on its through bolt which held the engine in place, without pushing it to one side or the other so the powertrain is free to slide to its own position along that bolt. I removed the headsteady, back wheel and shocks. I tightened the rear isolastic so that it had no clearance and was solid, this will now tell you if the rear iso unit is totally to blame, it will also allow you to measure the gap between the front iso main tube ends, and the inside of the frame lugs so that when you re fit the front iso components, you can ensure they fit perfectly in their gaps without pushing the front iso tube to one side or the other in order to get them in the available gap. Machine/shim or adjust so that when fitted and adjusted, they do not twist the powertrain to one side or the other. But first, the rear iso with the front just held in place by the through bolt. I now lifted the swinging arm up wards to see that the lower shock mounting points where in line with the top shock mounting points on the frame. Mine where maybe an eight of an inch to one side so that the rear shocks were leaning, I therefore inserted suitable washer between the rear Isolastic frame lug, and the adjuster so that it pulled the whole power train into its central position so that the shock absorber lugs lined up. I would then measure your gaps at the front iso whilst the rear one is still solid, when you have made a note of these for later, no0w try and adjust the rear one and see if your problem remains, I would have though that with the rear iso being on a vernier that you adjust on one side, as you unscrew this, it should naturally release the pressure from the other side. On mine I do have a vernier type on the back, but I have the standard shims on the front as these are easier to swap around in order to not push the front over to one side as this is what causes vibration on most bikes and causes the PTFE washers to wear to a wedge shape, as each iso unit must be perfectly parallel and in line with each other. I tried the Dave Taylor headsteady but found it gave no improvement over the Norvil type but did increase vibration which is why in the video I went back to the Norvil unit.

@@petercharlton515 The Hemmings adjuster is a simpler type than the OEM vernier. Just two parts, an adjustment collar, internally threaded and a short externally threaded spacer tube. Rubbers are the original bushings for pre-Mark III bikes. One advantage of the Hemmings setup is it can be adjusted without needing to slacken the through bolt/stud since the adjuster collar does not take the clamping loads from the bolt/stud torque. One thing your advice made me realize...when I have been measuring the gaps, the bike is on the centerstand and on a sloped garage floor. Not sure if that contributes to the off-centerline issue I seem to have. Thinking weight of frame/back of bike may be leaning away from right side of rear iso mount, taking up all the gap at adjuster unless I pry frame towards the right. Will try to find a flat place to re-measure things or turn bike around 180 degrees and re-measure....should make the problem move to opposite side of the iso mount.

@@TornadoCAN99 I just looked at a picture of the Hemmings set up, so the two smaller externally threaded parts, does one end fit against the frame lug, and the other fits against the internal bonded tubeing of the Isolastic rubbers that the bolt passes through? In which case, I do think the position of the rubbers to the main isolastic tube is critical. I would now suggest removing the rear wheel and the shocks in order to assertain the powertrain is in its proper position so the shock lugs match up, you can unscrew the Hemmings large adjusters so that whilst in position, they do not actually affect anything, you should see a gap on both sides of each adjuster to shop they are not affecting the position of the gearbox cradle. Then you need to somehow slide the gearbox cradle along the internal rubbers so that your swinging arm lugs line up, then tighten both adjusters completely to check the front and top as I suggested before. When you then do the isolastic adjustment, ensure you adjust each side by the same amount so that you dont affect the now centralised power train. As for your checking it on the mainstand, not sure this would be the cause of your vibration when riding it though.

@@petercharlton515 To be clear, there is only one Hemmings adjuster per ISO mount, not one on each end of the cradle tube. The OEM spacers/abutment is still in place on the other end. " does one end fit against the frame lug, and the other fits against the internal bonded tubeing of the Isolastic rubbers that the bolt passes through?" Yes, that is correct. The threaded stub tube fits between the internal bonded tubing and the frame lug, with the stud passing through it all. The adjuster then threads inward or outward along the stub to adjust the gap to the cradle tube. Will make some checks to see if issue can be identified.