So how do I install my new isos?

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Apr 15, 2004
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Well, I got the frame back from the powdercoaters and I must say it looks very nice indeed. Now it's time to install my new vernier iso kits. But how in the heck do I shove those things in?

These are the Mk3 style, consisting of a long tube with all the rubbers bonded to it. So you have to shove the whole thing in as a unit. I understand I'm supposed to lubricate it generously with silicone grease, but then what? Start whacking away with a big Texas hammer? :wink:

awaiting insight,
Think it has to be a rubber grease, there is a special type. I ordered mine with the iso conversion kit. Some greases will disolve the rubber over a long period of time. Make sure the inside of the tube/mount is really nice and clean, grease the rubber donuts up good and the inside of the tube, and slowly, at an angle, get the first one started into the tube, the last bit, before it can turn so it is straight in the tube, will be the most difficult part, but it will go in, use a blunt instrument, to work/push it into the tube. Might be a good idea to place the tube , wrapped in clean rags, in the bench vise too, and use good gloves to protect your hands, to avoid offending the ears of the neighbours, when during pushing, things slip about and you wack your hand into the tube or something...just a suggestion :wink:

The second donut will be a bit more difficult, because, by then, it will have to go into the tube from a straight angle, but it WILL go in with a bit of concentrated effort :wink:

The donuts and tube have to be pushed far enough into the tube to get them pretty centered, ends looking just a bit out, or just a bit in, same amount. If I remember correctly, the front mount will be a bit difficult to get into the frame again, but it can be done, and the rear mount, can have all the parts exchanged without being removed from the frame, just support the frame/cradle etc properly, not sure it can be done with it on the center stand, but maybe.

One way or another, it will all work, and you will be perhaps very pleased with the results. Mine have been in now for 5-6 years, and that conversion, is the first, most important one I would be making to any bike I ever worked on, the future. From all the little changes I have made to my bike over the years...that one was the one that did the most to make it the pleasure it is today to drive. Nothing was worse, than those old, loose, crappy original iso setups...all they did, was teach my bike to Hula dance :wink:

May the gods of Norton repair, watch over your shoulder.....

Do not use a Texas hammer here!

Put a liberal coat of grease on the ID of the tube and all over the rubber donuts. And as Hewho instructed, use a blunt instrument to push the donuts into the tube. With enough pushing a poking it’ll go together; you’ll see.

Hey Debby, get Windy to tell you about lathe turning down the rubbers to 5/8 width before insertion for a more compliant set up.
You can machine the rubber on a lathe?! :?

Interesting idea. DD's idea was to drill some holes in them but he hasn't had a chance to do one yet.

I had just sort of resigned myself to living with the additional vibration...

as you have heard the rubber is harder in the new isso;s and like greg said I narrowed mine up as a way to soften them some. the way I did it was to chuck the tube ass in the lathe with a tail stock to support the other end. with a die grinder and cutoff wheel I spun the isso and used the cutoff wheel to narrow them to .400 thou. it did soften them up quit a bit. I was thinking of trying .300 next to see it it is to much but the .400 worked quit well. also it was a messy job with all the rubber dust :lol:

how do I install my new isos?

Debby, I instaled a set in a customers 850 a couple of months ago, and used the factory 2 piece tool for the front mount, the rears are relatively easier, in that they kind of pop in after you insert at an angle and twist. Use plenty of red rubber grease or napa silicone grease. The factory tool is tapered so that when you insert the isos in one end they insert into the mount at the other end while being guided by the the other tool. I use a large rubber hammer on the guide tool.
I have done several of these and one trick which might be fairly obvious is to make sure that the inside of the tubes where the isos go in is clean and free of paint (especially if it's been powder coated), rust and baked on rubber residue. I use a rotary wire brush in a hand-held drill. Then plenty of red rubber grease and a plastic mallet after first starting the assembly in the hole as far as possible by hand. I'd be disinclined to machine them as I'm fairly happy with the absorption qualities of these new isos for my style of riding and if you are replacing old isos you would probably enjoy a considerable improvement over what you previously had.
I got the rear one installed! :D :D :D

Wasn't too difficult at all. I lubed it liberally with silicone grease and just did what you guys said. Piece of cake! The front may be more difficult as you have to squish the rubbers down more, but I'll worry about that later.

I decided not to machine the rubbers as these feel reasonably soft to my fingers. I want to use them as-is and see what I think.

My excitement was somewhat dampened though (no pun intended) when I tried to fit the cradle assy to the frame. It doesn't f***ing fit! With the end caps, PTFE washers, and collars installed, the iso assy is several mm wider than the brackets on the frame :cry:

Does that sound familar to anyone? I'll have to look into to it in more detail this week (I'm done for tonight) but I think it's gonna mean another trip to the machine shop.

I think the end caps may be different for the adjustable isos, I got new ones for mine and also new rubber boots as these did not fit either. You may have to machine an mm or two off the original end caps. I believe the nylon washers are the same size for both.
Dave M
Yes, I see there are different part numbers for the Mk3 endcaps. So I could either buy new ones or have the old ones machined. Probably end up costing the same either way.

I guess that's why the Andover kits include new endcaps. Norvil's kits did not, so they weren't quite as good a deal as I thought :?

So how do I remove my new isos?

I think I see the problem. I appear to have misread the vaguely-written instructions and installed the iso unit backwards :cry: The parts are slightly asymmetrical so they have to be oriented correctly.

So I guess I have to press it out, flip it around, and put it back in again. Then I think it will fit. But how do I get the stupid thing out? Do I need an arbor press? Usually pulling things apart is easy and putting them back together is harder. This time it's the opposite...


The isos are designated to go in one way rather than the other simply for ease of access for adjustment once they are actually on the bike. They will however work in either direction, I know this because I inadvertently built one the other way round and it makes no difference to the fitting. My suggestion is to fit the collar with the locking grub screw all the way in until it bottoms out on the threaded tube and tighten the grub screw then press it inwards towards the mounting tube until it bottoms out on the collar, the washer and the spacer. You then tighten the other adjustable collar all the way in until the whole thing is tight and unscrew it by the specified amount once the whole assembly is in the bike. If you have had your swing arm/iso carrier powder coated you should also file the paint off the end of the mounting tube this could be up to a mm or so thick and give you fitting problems.

good luck
If that's the case these aren't going to work for me. I've already done all that, and it still doesn't fit. It's too wide by some 2 mm. Maybe I'll just have to buy a set of the standard parts and use my Hemmings collars. That stuff all fit.


iso's install

I have seen on the net that older frames require modification for the front set. can not find it now but it's out there some where. CNW's or maybe BrittBikes.. good luck! Chris
Well, I got the iso unit out. Pretty easy actually. I slipped some threaded rod thru the center tube, used a nut and washer to protect the end, then gave it a few good whacks with a deadblow hammer. Out it came, easy as pie.

So I reversed it and put it back in again. The more you do it the easier it gets huh? It still doesn't f***ing fit though. It's some 4 mm too wide, which coincidentally is the exact width of two ptfe washers. If I leave both washers out and run the collars down dead tight, then the assy just slips into the frame. So to use these, I guess I'd have to have a machinist grind 2mm off something on each side.

That's too much of a PITA for me though. So I knocked it back out. I'm going to order the stock 1972 pieces and use my Hemmings collars. After seeing both I think that's a better design anyway.

So, just another crappy pattern part that doesn't fit. I expected better from Norvil.

Debbie, You could actually just machine off a bit from the threaded end of the iso that the locking collar fits onto. The collar could then go further down this shaft (asuming there is adequate additional thread) and give you the clearance you need. This would I think be a simpler engineering job than turning down the collars and at a pinch if you are too impatient to wait (like me normally) you could simply file it down yourself. Also make sure first that this locking collar doesn't have any impediment inside which prevents it from bottoming against the threaded shaft, sometimes the thread where the grub screw comes through can be slightly damaged internally causing this.
Debby, is there anyone in your area with a mk3? If so , ask if you can remove the mount assembly for measurements. Maybe their bikes apart already! You ARE in snow country, yes? Compare parts. Even OEM parts can be wrong, and if someone else is making them, where did they get the dimensions? If they are using an original part, instead of the blueprint for specs, there could be real problems. Lots of variables that way. Also measure the frame spacing.
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