Front isolastic replacement

You should be able to install the front iso. mount from below the brackets. Sometimes helps to remove the head steady and jack the engine up a bit to facilitate installation. Have you checked the new assembly is the same width as the one you removed and also that the iso. tube/rubbers is in the same position within the iso. mount? Whilst you're about it very worth while to lock the rear iso. assembly (zero clearance, mounting stud torqued up) and then mount the front iso. minus spacers/shims etc. and measure the gaps each side between the iso. mount tube and inside of brackets and check each spacer/shim assembly is the same width as the gaps available. If not machine and/or install spacers as req. This helps to get the thrust faces parallel to each other front and rear. It's possible that you might find the front mounting brackets don't exactly line up with the iso. tube for the mounting bolt which would req. further machining. Unfortunately this is usually a result of Norton production methods and quality control.

Simon.

Before the pre Mk3 version was available you fitted a MK3 vernier iso but you also had to take 1/4" off one side of the large tube which is what I did, you may have to look at your current mount and shave a few thou off, once setup correctly it does fit back in.

Previously gary_hawksworth wrote:

Can anyone advise how I can get the front engine mount back in the frame?

I'm in the process of replacing the complete front iso on a late 750 with an RGM vernier replament for a pre mk3.

I have it all assembled in the front engine mount but cannot get the mount back in the frame. The engine is in the frame.

Gary

As already said, from the bottom and yes it is tricky with the end caps in place. One way (not necessarily the best) is to unbolt the top mount and let the engine pivot down. Slide the Iso assy into place from below and jiggle the engine side to side so that the Iso plates align with the cases and between the frame tabs. It is usuallythen possible to slowly jack the engine up with the mount but with the mount ahead/above the engine so the Iso caps fit between tabs and then the cases follow in between the Iso plates. Harder to explain than to do really.

I converted my Commando to a front vernier set-up last year. The old gear just fell out but to get the new bits in I ended up taking off the head steady and jacking up the engine. I even had to move some of the electrics and use another jack to spread the frame before the new gear finally went in place.

A final surprise was finding that the engine had now moved forwards by about 4mm. The old bits must have really been past their sell by date. No wonder the handling was iffy. I want to replace the rear one with a Vernier but have been informed that thiswill involveremoving the whole cradle. ie a complete strip of inside the frame. You don't have this problem with a Dommie!!!

You can change the rear ISO without a complete strip, its detailed elsewhere but I can post it if required.

Short version is you remove the head steady, the rear iso through bolt and a few other parts and lift either the rear of the bike up or push the engine up, the rear iso tube is exposed and you can remove the iso's, if you also take off the primary you can get to both sides but that is not always nescessary.

Found a write up, this one ahs more parts removed than you need to but shows the basic principles.

http://www.accessnorton.com/rear-isolastics-t16887.html

I converted both front & rear mounts on my mk2a several years ago, the rear was a bit fiddly, but deffinately didn't have to remove the cradle, just shuffle it arround so I could get enough access to remove the old rubbers etc & fit the new, it was a direct replacement with no mods needed. The front mount required the tube to be machined, I seem to remember 7mm off one end. As has been said, back then you just substituted mk3 rubbers & abutments etc, so I measured a freinds mk3 tube & machined mine to match. Fitting it back to the bike was indeed a chineese puzzle, I tried umpteen ways to get it to go in & had almost convinced myself that it wouldn't fit when it sort of just fell in. I managed to knock paint off of the frame & the mount, but it did fit, just.

Subsequent removal & refitting has given the same headaches so when I built my latest Commando, I used vernier type for the rear, but retained the shim type for the front on the basis that it's easily removed & can be shimmed up in a vice & refitted without removing most of the paint work on the frame & skin from my knucles & takes only slightly longer to do than adjusting the vernier type, plus it gives me a good oppertunity to check the condition of the rubbers which, due to the difficulty of removal & refitting, I tend not to look at very often in the vernier type.

Regards, Tim

If you replace the rear Iso rubbers with later vernier adjustable items the cradle will have to come out. Mick Hemmings makes an adjustable end cap in stainless that utilises the std original rubbers and the mounting tubes do not need modifying, front and rear. Result.