Solid rubber in isos - anyone tried it?

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grandpaul

grandpaul

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Has anyone tried stuffing the iso mounts solidy with full-size rubber donuts?

Kenny Dreer and I were musing back and forth; our conclusion is that it would probably be a good mod. neither of us has tried it yet...
 
The engine balance factor is tuned to the isolastic characteristic. If you change either one too much at best you'll shift the vibration where its not wanted, at worst you'll crack the frame.
 
I'm using 5 bushes on the rear iso. Seemed to me that the rear is more a fulcrum than anything. I understand that Mick Hemmings used 5 of them at some time. I had to turn them down on a lathe and skipped the buffers. Can't say much one way or the other if it's a big deal.
 
On my racebike several years ago I turned down the large rubbers to match the size of the small rubbers and then sleaved the tube down for a snug fit. It increased the vibration and rider fatigue factor quite a little. Eventually went back to stock and found out I turn better times when I am comfortable and happy. Jim
 
Has anyone tried stuffing the iso mounts solidy with full-size rubber donuts?
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If you ever get the chance to watch the Duke Norton video you'll hear Bob Trigg the designer describe how they first used solid rubber and gradually split the rubbers until vibration came down to an acceptable level at <3000.
 
I added a fifth buffer to my rear iso when I installed the MKIII setup this year. I wish I hadn't. There's more vibration at 3000 than I like. Not sure if that's the reason but it's something that I can't change now.
 
Years ago I added an extra rubber to my front isolastic (turned two short bushes to hold the small rubbers). Towards 2500 rpm the engine was visibly shaking less but riding the bike there was more vibration so I changed it back to standard.
 
My other Commando had custom aluminium engine mounts when I got it complete with an extra mounting point (also rubber mounted) under the gearbox. The builder had used a pair of car (Australian Holden) idler arm bushes per mount, one from each side, to make a solid rubber mounting.

Transmitted ALL the vibration beautifully! I've found that the tube he used is the correct size for the smaller rubber buffers, so I ordered six of those and fitted them. When I get my head for the bike shortly, I'll get it back together and report.
 
Transmitted ALL the vibration beautifully!
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Well Fullauto if you fancy shaking off your bike this seems the way to go! : :mrgreen:
 
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