Hello folks: my 1st time asking a question here. Am rebuilding a 1971 Commando. After some reading I see you adjust by adding shims to left on the front and to the right on the rear. But on initial installation how many shims do you install on the off side where the bolt goes in.
Dear Dan, here is example of what I would do. Start with front mount, build it up in a vice, fit end caps to tube without shims, build up assembly with ptfe washers and outer abutments, put bolt in, may need an extra washer at each end to take up space of frame lugs, no need for outer dust covers, tighten it up and measure gap with feeler gauge take your 0.010 off and you have a figure for total shims needed fit half behind each end cap, I would wipe them with oily rag when fitting, new dry shims and future moisture makes rust. Anyway you never get it right strait away, so reassemble in vice again and see if you are close enough to book figures, if so you can fit outer gators.
Rear would be similar with iso gearbox cradle on bench
Personally, I would fit the Mk3 type Vernier adjustable isolastics at the rebuild stage. Much easier to keep well adjusted going forward.
Just bear in mind that the rubbers seem to vary in hardness from different suppliers. The latest offerings from AN are quite soft, like the originals, and have worked well for me.
I agree throw out the shimmed type and fit the vernier ones, I've had bikes with both and verniers are easier to check and adjust.
With the other guys having rebuilt 2 Commandos, buy both front and rear vernier Isolastic mounts, dead easy to fit and adjust.
Mine looked like this when taken apart
Thanks everyone for your comments.
Being new at this rebuild stuff I will attempt the shim method for my own knowledge plus I also have all the new pieces purchased. If I drive the bike as much as I hope I may wish I had gone the vernier route but such is life.
Just picked up a 1976 TY175 yamaha trials bike, luckily the weather here in Ontario is still ok for trials riding in our fields and bush.
Have a great weekend everyone.
Hi Dan , I suspect your frame is the early one where the ( poorly designed ) Centre stand pivots on brackets which are part of the lower frame. As such , this arrangement means the full weight of the bike when on the stand is not on the isolastics . The later frame means the isolastics carry the full weight when on the stand . This lends itself to faster wear and ‘distortion ‘ of the rubber inserts . I have rebuilt several Commandos of both type and in every case the isolastics on the early models have not suffered distortion . As others have indicated , the vernier type are much easier to set up and adjust .
After setting up the shims on my 1971 commando which is stripped to bare frame at this time, I see how it may be a huge pain adjusting in a normal situation when bike is assembled. Therefore I would like to know if there is an adjustable unit I should avoid or a favourite one I should be looking at. Beautiful sunny fall day here in Ontario Canada. Hope everyone is having a great day.
Only my opinion, but I would recommend you buy the Andover Norton Isolastic kits. They make complete kits for front and rear ISO’s to convert early commandos to the Mk3 Verniers.
I have used these myself and the latest offerings are good. The rubbers are pretty soft, very similar to originals. Some rubbers from other suppliers are too hard and don’t work as well and vibrations aren’t isolated at the lower Rev ranges.
If your Isolastics are in good condition there used to be a kit I think by Mick Hemmings? that provided the adjusters only that could be used with the O.E. type Iso's.
Mick Hemmings adjusters are out of production and unavailable.
Andover Norton Vernier rubbers coupled with RGM stainless fittings was my route.
I got mine from Norvil, very easy to install and adjust.
Checking the cost at the time AN and RGM were all around the same price.
Definitely recommend fitting rather than mucking around with the old ones.