Isolastic solution and handling improvement

hobot said:

... Problem is after molding they continue to CURE. ie get harder . Heat . TIME and to a lesser degree LIGHT continues the curing action...Make's you think what's happening on a hot summers day

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Relatively speaking, how significant is the "continued" curing on these isolastic buffers over a typical lifespan?

I suspect a MUCH more significant issue is actual physical wear / deterioration, especially on the old style units that ALWAYS show significant ovality on the I.D.

Perhaps the wear, over time, and the continued curing, over the same time, cancel each other out (to a degree)...

pommie john said:

Can't you get a similar result just by using Mk3 Isos and running them a bit tighter?

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It's my experience with the vernier isolastics that you can set them to be comfortably smooth or stiffen them up for tighter handling. Whatever point of compromise between the two is a personal preference. Obviously, the front mount needs more slack than the rear and the rear is more critical for keeping the swingarm aligned. It is nice, though, to be able to whip your tool kit out at a roadside stiop and experiment. Can't do that with shims!

Don't forget that part of this equation is the lightweight pistons and rods, which changes the balance and decreases vibration (see Jim, I wasn't asleep in class after all). So the lesser vibration allows you to tighten the iso's to get better handling without sacrificing as much comfort. So a solid isolastic isn't so much of a goal in itself.

I have to admit I wonder why not keep the stock isolastics and tighten them down to no clearance. And I would also like to point out to the nay sayers that there are a number of people who are proud of their heim joint hinge-effect prevention devices. There must be something to this.

So will turn this back over to the more learned in the group with these questions:
1.) Would it be necessary to bond a solid iso to the mounting tube? Or could it float?
2.) How critical does it become to have as little friction as possible between cap and collar?
3.) Would it be a benefit to pour the isolastic so that it were proud of the mounting tube by a small amount so that it would be compressed when mounted?

Russ

After Bob Patton's device this is just academic to Peel. Bob says he stuffed 6 big rubbers in back to control the time-sag factor on his link leveling.
I may try my own poured in place or machined cylinder rear iso cushion to see if anything extra good happens or intrusion of vibration. Do understand that whether one realizes it or not, the freq. of engine vibration over laps and interferes with the muscle and joint nerve position-load-motion-tension- sensors and processing, so pilot fatigue and errors creeps in when slightest mistake or lack of notice > SPLAT* I trimmed Peel's donuts to half narrowed edges. Ah.

I've seen old doughnuts go both ways, harden up or soften in decay. I guess it depends on how well maintained a bike, best ones too dry to soak iso's in oil.
I don't know elastic property - chemistry, just bring it up to be aware over time.

I can sure tell the effect of engine resonance on tire grip in a number of conditions. No one else is mentioning the advantage of dampened power pulses.
I think pulse hook up along with narrow tires combine wonderfully in Commandos.
360 cranks have widest pulses. The inline 4's big bang'rs have longer gap between their 'big bang' than 360's BUT their 'bang' is really a very hi freq vibe over 100 degrees or so. Only takes one excess at limits to crescendo into SPLAT* I find my iso Commando the most forgiving in grace periods to my excesses or laxes.
I think above is a big reason to retain the isolated power unit, IF it don't upset bike and pilot. You can not separate the piston pulse freq- crank configuration and balance factors from isolastic function in hot cornering to lazy pilot cruise.

What I would like to try beside beefing up the rear iso pivot point is to somehow restrain the leverage of swing arm on its cradle spindle area. Bob mentioned helms link to the swing arm itself tied to frame. That'd be a feat to ponder.

Peels set up ties both rear frame loops together and also the rear cradle plates to combine stiffness to resist chassis twist, yet I can feel chassis twist up, but so far never rebound but in one smooth predicable delicious release out of apex hardest at the point of least traction, flabbergasting impossible sensation to me.

hobot