Original Isolastics

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Marathon Man

Marathon Man

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Due to their marshmellow-like consistency I'm replacing the isolastics but I have a couple of questions regarding replacements. I'll upgrade to the MKIII vernier style but why do I see pics of four rubbers on the new rear kits and mine has five? Also, why do the inner bushings have a smaller diameter? It doesn't look as though they have any function whatsoever.

Original Isolastics
 
I assume the smaller bushes take over when the larger ones become partly compressed during normal vibration movement? (like a sort of re-bound effect)
Dave.
 
Right, the smaller bushes act as limiters as to how much the larger ones can compress and flex. As to the different numbers of bushes in the rear mount, I have no clue except to speculate that some bean counter figured out they could get by with one less.
 
I don't think the trade-off of, ease of adjustment for increased work in renewing the gaitors (which have a much shorter life than the original ones you now have), is worth it. I've not been pleased with vibration levels of some offered for sale and reconmend stock. At this stage, replace the mount and limit rubbers and ptfe washers, and shim the clearance before final installation of the cradle and front mount. ... Rick
 
I probably will use my original gaiters. They're in excellent shape, no cracks and pliable. I'm sure they'll still last longer than newly manufactured rubber. Unfortunately I can't say as much for some of the bushings which have sagged with age. Thanks for the replies.
 
Thanks GrandPaul. I may go with Commando Specialties. Seems they've got front/rear verniers for $260 shipped.
 
Anglophile said:
Thanks GrandPaul. I may go with Commando Specialties. Seems they've got front/rear verniers for $260 shipped.
Click to expand...

Are they stainless? I bet they aren't.
 
Are they stainless? I bet they aren't.
Click to expand...

They're not SS but my originals lasted 39 years with almost no corrosion. I'll place my bets with Andover Norton's parts to save $90. Sorry, I'm cheap.
 
Anglophile said:
swooshdave said:
Are they stainless? I bet they aren't.
Click to expand...

They're not SS but my originals lasted 39 years with almost no corrosion. I'll place my bets with Andover Norton's parts to save $90. Sorry, I'm cheap.
Click to expand...

I'm not pointing that out for any other reason than to make sure that Paul's price wasn't seen as unreasonable. And I don't call it cheap, more like price-conscious...

If that what I think it is weighing down your bike in the picture, I know how much those are to maintain. :mrgreen:
 
I'd love to do the bike up with all stainless hardware but I gotta be careful this time around. The little one is still in pre-school and the wife may be watching the checking account. :roll:
 
grandpaul said:
$260 for front & rear with new PTFEs & booties, delivered?

Wow.
Click to expand...

http://www.commandospecialties.com/Prod_Detail.asp?MSecID=54&ProdID=33

Original Isolastics


I found the backs, I have to assume the fronts are a similar price.

Art # : CS-1110
Name: Norton Commando Rear Iso Update Kit (Vernier 3 style)
Price: $99.95
Description:
This is the complete kit to update the Rear isolastic motor mount.

If you have a stock Commando with the original isolastics, they need to be replaced, guaranteed. If you're going to replace them then you need this kit. You don't need a whole toolbox full of shims etc, you just turn the adjuster to get the correct clearance and you're done.

Every Commando I've taken apart lately has completely worn out isolastic rubber bushings. This contributes to excess vibration which then leads to exhaust breakage etc.

These are made by Norton Andover in England and come with new PTFE washers. No modifications to the bike are required to use this type iso on the rear.

Basic instructions are included.
Click to expand...
 
I got the complete front and rear rubbers and spacers (4 rubbers in front and 5 in back) and circlips from OB for about $95. Not including the PTFE spacers and no verniers. I was going with my old setup with shims since I will not be putting much mileage on it. Haven't decided on the PTFE yet, probably from RGM since I need some of their stuff anyhow. There was a thread on the PTFE washers and some people have made them, you can get sheets of the stuff from McMasters pretty reasonable. Depends how cheap or convenient you want to be.

I'll bet those Commando Specialties iso's are the new Mark III style, I would be leery of them because if they are, they are the harder rubber for the heavier bikes.

Dave
69S
 
Looks like I have a new source. I'd been using Old Britts for the Andover stuff...
 
There was a thread on the PTFE washers and some people have made them, you can get sheets of the stuff from McMasters pretty reasonable. Depends how cheap or convenient you want to be.
Click to expand...

You need the bronze-impregnated stuff as PTFE will work flow and you will never maintain your iso clearances with unfilled PTFE.
 
I bought new MK III style Iso's from this guy on ebay-
http://cgi.ebay.com/ebaymotors/Norton-C ... _500wt_746
I asked him where he got the parts from and he said the stainless adjusters were from RGM and the rubber bits were from andover norton. He also has the bronze impregnated PTFE washers for $10 each. Nice guy to deal with and the best price I could find. He also has the new front type that don't require any modification to the pre MK III front iso mount.
 
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