Isolastic replacement on 74 Commando

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Mar 1, 2007
Hello again. I have my frame dissasembled for paint and I am thinking about replacing the old isolastic rubber on my 74 commando. It does not have the adjustable type vernier. The bike I am restoring has only 2000 original miles. The rubber in the Iso looks pretty darn good and soft but I would hate to have trouble later only to have to take the bike apart to replace them at a later date. My question is how much modification is required to go to the MKIII style adjustable iso AND WHY ARE THEY SO DAMN EXPENSIVE?? Where is the cheapest place to order the upgrade and still get good quality??? I may just replace the rear iso for access purposes now and replace the front later in the spring because it is easy to get to and I will be more adjusted to the finance end of the deal?? What do you guys think??? Replace them or just keep what I have. Is there any problem with just replacing the rear for assembly and then the front in the spring before I actually ride?? Thanks for any insight---Mark Cigainero
The "old" 2000 mile ones would be on there a long time if it were me. The rear doesn't need a lot of fiddling the front needs a touch up now and than. Use the shims for a while not that bad. Spend the money on an X-ring chain.
You want to keep your old soft rubber if it is in good condition, this reduecs the revs at which the vibration dissappears. To get the vernier adjustment and keep the rubbers you can go the Mike Hemmings route which are adjustment collars which are locked to the end threads.

I would lean toward keeping the "old" iso rubbers. It's been my experience that UV is what kills rubber products. But the isos live in a dark environment, so there should be no UV degradation.
I have run into the norvil verner's having harder rubber. I still used them with a little modifacation to soften them up.

the mod is to narrow the large diameter rubbers. it can be done in a lathe either cold with a die grinder and a cutoff wheel (VERY messy) or freeze in dry ice and use a normal tool. I narrowed mine to 2/3 the width they came at.
hope this helps.

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