Isolastics replacement, upgrade - 74 850 Commando

I'm doing an engine rebuild on my 74 850 Commando. It's my first Norton and I bought it with a basket case motor. I seem to have all the original parts in apparently good condition but I figure while I'm in there, I might as well do everything right instead of hoping for the best on 40 year old rubber.
I've got the bottom end pretty much done and the head rebuilt but have been stumped for a while about how to proceed. Every time I start researching new isolastics I get confused and just walk away (I've had a few head injuries, concentration isn't always my strong suit).
Can anyone offer some advice on what to do/buy and where to buy it? I don't mind throwing a little money at it. Thanks.

you can start here: https://andover-norton.co.uk/en/shop-details/16920/isolastic-kit-rear-vernier-all-commandos-
and https://andover-norton.co.uk/en/shop-details/17047/isolastic-kit-front-vernier-pre-mk3-commando-
These will simplify the adjustments down to about a half hour as opposed to the original setup prior to the 75 vernier system. All bikes pre 75 had a shim type which is a royal PIA. what you buy is basically what the 75 bikes had as improvement to the design. I would also recommend the top head steady upgrade to improve the handling by using either a Dave Taylor, Comstock, type that cNw sells or old brits design. Then beef up the swing arm axle using split collars. do a forum search here for the mods. That will get the bike tracking right and upgrades you will never regret.
Cheers,
Thomas

CanukNortonNut said:

you can start here: https://andover-norton.co.uk/en/shop-details/16920/isolastic-kit-rear-vernier-all-commandos-
and https://andover-norton.co.uk/en/shop-details/17047/isolastic-kit-front-vernier-pre-mk3-commando-
These will simplify the adjustments down to about a half hour as opposed to the original setup prior to the 75 vernier system. All bikes pre 75 had a shim type which is a royal PIA. what you buy is basically what the 75 bikes had as improvement to the design. I would also recommend the top head steady upgrade to improve the handling by using either a Dave Taylor, Comstock, type that cNw sells or old brits design. Then beef up the swing arm axle using split collars. do a forum search here for the mods. That will get the bike tracking right and upgrades you will never regret.
Cheers,
Thomas

Click to expand...

Thank you. Exactly the information I was looking for.

Re. the front isolastic (aka "Nicker-lastic")....there is a slightly different length on the front mount housing on the pre-75 bikes...so the ISO insert you need should be specific to the pre-MKIII bikes. I just did my '74 850 with the Vernier adjuster set from Norvil in the UK....Stated it was correct length for pre-MKIII's with no need for modifying the housing. Went in just fine. I reused original PTFE washers and caps....so I only needed to order the one-piece inner bushing with the Vernier adjuster end fittings. Was the lowest cost option as well!
Have not tackled the rear yet...engine still in frame and this is a bear apparently without removing from frame.

Here 's video series depicting the swingarm upgrade mentioned above...I have not yet done that but intend to...

Also felt the same way when faced with this job. Some iso replacement kits and the later models use one piece rubber/metal iso inserts which require much more disassembly - mainly for the rear. And a real pain if you or a future owner needs to replace again. I used the original type replacement rubber disks from AN and kept the multi-piece construction. I cleaned up the minor rust on the inner metal pieces and painted them. I chose to keep the shims as I had plenty and it is not something you have to do often. I don't disagree that the vernier type is quicker but I don't want them on my bike. It wasn't as bad as I had thought it would be.

There is a lot of play there in that video. I seen the same issues on other neglected commandos. I bet it does the funky chicken walk when going around long sweepers.
New bushings, new shaft and the clamp mod will fix most issues with the swing arm and then get your 8 to 10 thousandth inch for each front and rear ISO will make the bike track a lot better. Some vernier ISO kits had too hard rubber so do a search here. The link I sent is good as I bought them from Andover and they are soft. I use Quad rings instead of O-rings in the swing arm and I also shim the outside of the beauty cap so I have only 0.005" of clearance between the engine cradle and the bronze bushes on contact fitting before putting in the Quad Rings and swing arm axle. It will not eliminate the 140 wt oil weep but it slows it down quite a bit.
Cheers,
Thomas

I went through the same dilemma a few years back with my 73 850. I ended up using the stock type Iso setup that needs the shims. I based this decision on the fact that I didn't plan to ride my Norton all that much. Maybe a couple of thousand miles a year as I own other bikes. A little extra effort every 4 or 5 years isn't that big of an issue to me. If it was a daily driver the adjustable type would be a no brainer.

CanukNortonNut said:

you can start here: https://andover-norton.co.uk/en/shop-details/16920/isolastic-kit-rear-vernier-all-commandos-
and https://andover-norton.co.uk/en/shop-details/17047/isolastic-kit-front-vernier-pre-mk3-commando-
These will simplify the adjustments down to about a half hour as opposed to the original setup prior to the 75 vernier system. All bikes pre 75 had a shim type which is a royal PIA. what you buy is basically what the 75 bikes had as improvement to the design. I would also recommend the top head steady upgrade to improve the handling by using either a Dave Taylor, Comstock, type that cNw sells or old brits design. Then beef up the swing arm axle using split collars. do a forum search here for the mods. That will get the bike tracking right and upgrades you will never regret.
Cheers,
Thomas

Click to expand...

So I am starting a rebuild/restoration also on a '74 Commando. So I need both these items if I understand you correctly?

The rear one is a lot easier to go Vernier if you use the Mick Hemmings version, which uses new end pieces and does not need the old rubber changed.