Isolastic Thoughts

I am dealing with isolastic on my current project.. Granted they work and have had various design upgrades in the past and it all you can buy ... I assume that there is an agreed fact that the "rubber" absorbs vibrations, hence its repeatative inclusion into current upgrades.... OK fine..

Has anybody used or tried , Teflon, Nylon, silicon, wotevelon, bushing as seen on many car suspension products.... The right material, what ever it is could be a "slip on" with spacers to seperate.............. Just a thought outside the box, tho probably discussed before..

A high (adjustable) pressure rubber bladder might work.

olChris said:

I am dealing with isolastic on my current project.. Granted they work and have had various design upgrades in the past and it all you can buy ... I assume that there is an agreed fact that the "rubber" absorbs vibrations, hence its repeatative inclusion into current upgrades.... OK fine..

Has anybody used or tried , Teflon, Nylon, silicon, wotevelon, bushing as seen on many car suspension products.... The right material, what ever it is could be a "slip on" with spacers to seperate.............. Just a thought outside the box, tho probably discussed before..

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Those harder materials you mentioned would work just like the automotive suspension items. Transmit every motion. Difference is, you have no tire/spring/shock to absorb. May as well bolt it solid.

In discussions with 3M about products suitable for building motor mounts, their windshield adhesive got the best recommendation. You might try it and give us a report. I find the Comnoz Spring experiment interesting.

Russ

rvich said:

In discussions with 3M about products suitable for building motor mounts, their windshield adhesive got the best recommendation. You might try it and give us a report. I find the Comnoz Spring experiment interesting.

Russ

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I work for 3M and not sure that windshield adhesive would work. This is a very soft pliable material. The crosslinking isn't very good due to solvent base. There are other rubbers that we make that might work, but would need to be bonded to shaft during manufacture. It might be possible to fabricate with spacers but shape would still need to be molded. Harder wear resistant materials (platics) coud be made but as said previously would transfer vibration.

There may be better rubber materials with higher durometer that would hold shape better and perform better than what is available but would take research and testing and then method to manufacture parts.

Since the oem stuff works fine for the purpose - I don't see any benefit in trying to find some new substance that does the same thing. If you want it stiffer, you can do that by adjusting the clearance rather than putting some different material in there.

mike996 said:

Since the oem stuff works fine for the purpose - I don't see any benefit in trying to find some new substance that does the same thing. If you want it stiffer, you can do that by adjusting the clearance rather than putting some different material in there.

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I think the OP was thinking life and wear rather than adjustment...but I might be wrong.

Its a waste of time trying to improve on the Norton issued cushions material in the front iso, if ya still want the low rpm isolation threshold and not be so soft and sloppy ya loose the nice handling of sane turning. The range of available cushion compliance/elastisity has been reported many years ago to find just ain't that much variation to really change much in isolastion threshold or frame stabilizing. After reading for over a decade the various reports of experiements gone sour, too soft too hard - I grind a bevel in the larger front cushions to get softer more progressive isolation and stuff 2 extra cushions in the rear. Bob Patton who really came up with the links that transfroms a sloppy Commando into a world class load handler that's driven me insane w/o cure - stuffs 6 big cushions in his rear mount and still complains that they sag after 6 months to change the alignment of his 1st ever rear robust link.

Re-read the development of the isolastic and testing to find they had to reduce rubber area 3X's before isolation onset below 2000 rpm. Both Frank of Norton test rider fame and my Peel isolated below 2000 and for sure didn't bother Peels handling but improved it and pilot sense of tire patch w/o anything interfering or reasonating to obsure that vital sense for really kicking up heels to tril the breath out of ya.

There are air bladder tubes available that could fit in the iso tube around the mount bolt so please someone try it - just not me as I've no more issues of isolastion or handling so have moved on, but still entrained on attempts to get more out your C'do pleasure and security. I will be fitting air bladder under engine to fine tune the support rather than a fixed spring/support hassle like Jim Comstock came up with recently.

I've always wondered how adapting Eric Buell's uniplaner engine support system would work on the Commando. Maybe use the iso for the rear and the links for the top and front. Jus thinkin'...

Rubber is the best material to use for vibration isolation because it has built in damping. Steel springs don't work well because they have no damping. Without damping there will be a severe resonance.

There is a very good use for the spring as the Norton( they put a spring on the MKIII) and Commoz know. The rubber will isolate the vibration most completely if it is very soft. The trouble is when it is to soft it will be compressed to much by the weight of the engine. If the weight of the engine is removed from the rubbers by a steel spring that takes all the weight off the rubbers then the rubbers can be much softer. The spring must be a pretty soft spring as well so that the force of the vibrations are taken by the rubber. The spring will not cause resonance because as the engine moves there will be hardly any difference in the force of the spring from one end of it's travel to another.

I have a home built Isolastic Triumph that has a valve spring holding the front of the motor up to relieve the pressure on the single Norton iso mount above the head, so I understand this from experimentation as well as theory.

Bernad Hopper was paid by Harley to develop their isolastic system with rod links d/t the multi freedom of the rubber supports. How clever to use rod links eh.