Which isolastics for '71 Commando?

Which Isolastics are the best for 1971 Norton Commando? I currently have the bike stripped to frame only.

nortones7 said:

Which Isolastics are the best for 1971 Norton Commando? I currently have the bike stripped to frame only.

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Hi, welcome. Lot's of previous discussion if you care to use the search function.

I bought replacement iso rubbers from RGM, and although I am generally satisfied with the quality of their products, I found the replacement rubbers too hard, they transmit more vibration than the original ones.
My advice is to make sure you buy the softer rubbers .
And while the bike is stripped you could consider an upgrade of the iso adjusters, I use the adjusters from Mick Hemmings, they work fine.
Just like the Mk3 system,they make adjustment an easier job than the original system with the shims.

I bought my rubber parts for the iso from Old Britts, supposedly the early style softer material. But the part numbers are still for a 71, not 68-70. I have a feeling that the parts were harder than the originals, but I didn't do any test to verify that. I should do that, I still have my originals and it's easy enough to take off the front iso. You can drill holes in them out to soften them up too.

Dave
69S

Most any will do. Make sure the rubber is fresh.

I got mine on e bay from Commando specialties, I have a 71, they are the venier ISO's designed to fit the 71 without modification. I suspect they may be harder rubber as there was no way to compress them with your fingers (per the manual) The bike is solid in handling with very low vibration. very happy with them.

Would strongly recommend the adjustable ISO's

I think Old Britts now has an adjustable ISO to fit the older frame with out modification.

Dennis

I may be the only one whose tried to drill rubber in brake or isolastics > can tell no one else has because I found the rubber just expands to pass dril then closes up barely leveaving evidence of a hole. The orginal rubbers must of been half again as soft as the last couple decades being sold because Frank Damp says his test Cdo's all isolated ~1800 and essentially everyone last 20 yr feels the replacement are harder than desired, so I reccommend bench grinding a 45' bevel on front big cushions leaving a ~1/4" flat contact rim and put the left over old ones in the rear iso. Tired this in Peel with dyno balanced crank and rod links to isolate ~1800 and Trixie just stuck together like factory issue ~2200. In 4th 19T Trixie isolates going low 30's mph at 2500ish rpm while prior jarred through peg bars and seat to go that slow. Someday there may be 3 or more happy bevelers out there and a lot more when word gets out. IIRC DynoDave measured a handfull of various vendors isolastics to show a range of softeness but all still apparently too hard.