74 Mk2 - rear iso mount (2019)

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finally got around to removing the rear engine mount center stud. check out these ios mounts. you might say, just a little off center -

74 Mk2 - rear iso mount (2019)


74 Mk2 - rear iso mount (2019)


trying to do this without removing the engine, gearbox, and even the primary chain case. no problems so far - hopefully no future issues. I plan on using a slide hammer, in from the right side to drive out the rubber mounts.
 
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going on 72 - i'll be lucky if I get another 20 :D. actually, the slide hammer (brain fart idea) didn't work out. my large unit's center shaft was too big for the iso bushings, my smaller slide hammer didn't have enough reach. anyway, took a 1 inch nylon rod and a dead blow hammer, and everything came apart without issues. not planning on the 180 thing or reusing the originals. sprung for a set of Mk3 vernier types. now I need to get in the rear engine mount and clean out the inner cylinder.
 
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Well you pick your poison of choice. In spite of madnorton claiming they have the durometer on the rubber correct...if you put in a MKIII stiffness/vernier item, you may well have more vibes and to a higher RPM than before. The most mod I would choose for my own bike is the early rubbers with a shorty Hemmings adjuster. Only after scientific measurements or dozens of folk claim they function like the original early soft type would I get one of the one piece iso's...
good luck
 
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I've heard on these forums doing the rear iso update to one piece is not possible with the engine in frame. Pls prove this wrong ;-)

For removing, I thought the standard way was to use a long screw driver to turn each puck sideways in the bore and then it would come out easier? Glad your pound it out method worked. I have the MH adjuster cap and will need to replace my rear iso this winter....
 
I've heard on these forums doing the rear iso update to one piece is not possible with the engine in frame. Pls prove this wrong ;-)

For removing, I thought the standard way was to use a long screw driver to turn each puck sideways in the bore and then it would come out easier? Glad your pound it out method worked. I have the MH adjuster cap and will need to replace my rear iso this winter....
"Pls prove this wrong" -- OK, it's wrong. not that i'm any kind of Norton expert, but I just finished the Mk3 rear iso with the engine in frame and the primary chain case assembled and in place. it was a bit tricky, but very doable. one thing I found is having the end cap, Teflon washer and adjuster in place, as the one piece iso mount is pushed in from the right side, while screwing on the adjuster. with the adjuster screwed in all the way, push the center iso shaft max left. this allowed me to install the RH end cap, Teflon washer, and abutment. getting the RH abutment in place was a tight fit, but all it took was a slight tap with a plastic mallet. I backed off the adjuster several turns as i set the RH abutment and secured with a setscrew. i positioned the adjuster, and backed off 1-1/2 holes per the instructions (reset to .010" per LAB's suggestion). the way I did it was a bit different from the forum instructions posted by Michael Taglieri, since my primary chain case was installed. I had to assemble everything from the right vs the left as the instructions stated. I also referenced instructions from RGM Motors and the kit instructions from Andover Norton. BTW, my 74 Mk2 is pretty much just the frame, front and rear wheel, and engine and gearbox. the oil tank, horn, oil filter assembly, and battery tray assembly were all removed before hand, as well as the head steady mount. my engine and gear box assembly was pretty much supported by the center stand, and I lifted and supported the frame (from the rear) with an engine hoist. when I got the gaiters installed, lowered the frame, and all it took was a little wiggle-giggle and the rear iso center stud slid into place. I was kind of sweating this job, but honestly, it was easier than I thought. hope this helps....

next task at hand, front mount.
 
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i positioned the adjuster, and backed off 1-1/2 holes per the instructions.

That method is unreliable. I suggest you insert a (0.010") feeler gauge and check it slides freely at various stages during stud tightening as you may find the clearance reduces as the stud/nuts are tightened.

Same goes for the front Iso.
Edit: Always check there is clearance after tightening as running the Iso. 'tight' can break the frame.
 
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That method is unreliable. I suggest you insert a (0.010") feeler gauge and check it slides freely at various stages during stud tightening as you may find the clearance reduces as the stud/nuts are tightened.

Same goes for the front Iso.
Edit: Always check there is clearance after tightening as running the Iso. 'tight' can break the frame.
thanks for the heads up. haven't assembled or torqued up the center stud, but will double check and set with .010 feeler on final assembly - :)

edit: went out in the garage, and reset the adjuster from 1-1/2 holes to the .010 feeler gauge adjustment. again, thanks for the insight....
 
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"Pls prove this wrong" -- OK, it's wrong. not that i'm any kind of Norton expert, but I just finished the Mk3 rear iso with the engine in frame and the primary chain case assembled and in place. it was a bit tricky, but very doable. one thing I found is having the end cap, Teflon washer and adjuster in place, as the one piece iso mount is pushed in from the right side, while screwing on the adjuster. with the adjuster screwed in all the way, push the center iso shaft max left. this allowed me to install the RH end cap, Teflon washer, and abutment. getting the RH abutment in place was a tight fit, but all it took was a slight tap with a plastic mallet. I backed off the adjuster several turns as i set the RH abutment and secured with a setscrew. i positioned the adjuster, and backed off 1-1/2 holes per the instructions (reset to .010" per LAB's suggestion). the way I did it was a bit different from the forum instructions posted by Michael Taglieri, since my primary chain case was installed. I had to assemble everything from the right vs the left as the instructions stated. I also referenced instructions from RGM Motors and the kit instructions from Andover Norton. BTW, my 74 Mk2 is pretty much just the frame, front and rear wheel, and engine and gearbox. the oil tank, horn, oil filter assembly, and battery tray assembly were all removed before hand, as well as the head steady mount. my engine and gear box assembly was pretty much supported by the center stand, and I lifted and supported the frame (from the rear) with an engine hoist. when I got the gaiters installed, lowered the frame, and all it took was a little wiggle-giggle and the rear iso center stud slid into place. I was kind of sweating this job, but honestly, it was easier than I thought. hope this helps....

next task at hand, front mount.
Very impressive Joe! Ques pls,
Im staring at my 71 Comdo that long ago was changed to vernier isos.
I already renewed the front one and the head steady, but after what ive read im hesitating on the rear iso. I already bought a new Mark 3 type rear iso with the rubbers and bushes all molded to the shaft. Can i remove the old vernier rear iso
as u described u did with whatever version u had on your bike! Will the vernier threaded shaft pass completely thru and out the RH side?? If so, should i go ahead and use my new Mark3 parts or should i buy the earlier type with the individual shaft and rubbers??
Hope i described enough to make those easily answerable questions.
Thks, Tom
 
The rear is the most important to get right for the simple reason that it is awkward and a P.T.A. to access when needed for periodic lubrications and adjustments. C.N.W. machines don't use rear covers. The front is much easier to maintain. Covers needed due to proximity to road and rain grit.
And that's why the rear should be the vernier choice.
Use rubber grease to install. The more of it you use the more things can slip and centralize as you fit and finally tighten up using feeler gauge clearance as a final happiness point.
Softer rubbers are better ( 68 to 71 type ? ) but vernier are newer and slightly harder rubber. You want the motor to hop about up and down visually ( slightly of course ) . Just my experience.
Strongly recommend changing out the headsteady for a linked type. Lots of info here on Search for that.
 
Will the vernier threaded shaft pass completely thru and out the RH side??

Yes, it can be done without removing the primary drive and whatever Isos. you fit, the 'loose' cradle assembly has to be moved fully forward in the frame or the frame moved back whichever way you look at it, to provide the necessary clearance (the paint on the downtubes needs protecting from being scraped by the cylinder head fins).
Head steady, front Iso, exhaust system, Z-plates and battery tray need to be removed and the shocks either removed completely or disconnected from their lower mountings and the rear mudguard/fender perhaps detached from the brackets but I didn't find it necessary to remove the rear wheel.
 
This was the front replaced first (Remove the housing pivoting the rear) then the rear done in the frame with the front bolt back in place.
The Iso installed with a pushing corkscrew action.

The front is easier on the centre stand because the engine will pivot up easily on the rear Isolastic more so if the airbox is in place, the filter out on a ham can (?) and the two low and one upper 1/4" bolts on the plastic airbox so it can move rearward with the carburetors still attached.
The front Isolastic housing will come up from the bottom with the ends removed and engine rotated, lifted above the frame lugs the discs and threaded caps can then be installed.
Pushed from the T/S the D/S can be installed with the grubscrew but not with excess preload (perhaps) if the outer rubbers are not quite in the right spot, the T/S can then be fit and the housing dropped, 3/8" bolts fit then the engine rotated to fit the front 1/2" bolt.
The rear can then be rotated down and done in place, I lowered the engine on a floor jack with wooden protector based on that pic but wonder if the rear of the frame could be lifted as another option.
Or something like that, I read it was all but impossible or tricky but did not find that . Slow and steady.

cs.JPG


If the bike needs new Isolastics it will most likely need other area's addressed also.

The Vernier adjustment is easy based on the brand and thread class which means all that needs doing is add rotation which will reduce once the fastener is torqued to spec.
I forget offhand but with the RGM, 3 clicks maybe which will reduce to two (0,008 / 0,009")

Edited for detail.
 
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This was the front replaced first (Remove the housing pivoting the rear) then the rear done in the frame with the front bolt back in place.
The Iso installed with a pushing corkscrew action.

The front is easier on the centre stand because the engine will pivot up easily on the rear Isolastic more so if the airbox is in place, the filter out on a ham can (?) and the two low and one upper 1/4" bolts on the plastic airbox so it can move rearward with the carburetors still attached.
The front Isolastic housing will come up from the bottom with the ends removed and engine rotated, lifted above the frame lugs the discs and threaded caps can then be installed.
Pushed from the T/S the D/S can be installed with the grubscrew but not with excess preload (perhaps) if the outer rubbers are not quite in the right spot, the T/S can then be fit and the housing dropped, 3/8" bolts fit then the engine rotated to fit the front 1/2" bolt.
The rear can then be rotated down and done in place, I lowered the engine on a floor jack with wooden protector based on that pic but wonder if the rear of the frame could be lifted as another option.
Or something like that, I read it was all but impossible or tricky but did not find that . Slow and steady.

View attachment 84248


If the bike needs new Isolastics it will most likely need other area's addressed also.

The Vernier adjustment is easy based on the brand and thread class which means all that needs doing is add rotation which will reduce once the fastener is torqued to spec.
I forget offhand but with the RGM, 3 clicks maybe which will reduce to two (0,008 / 0,009")

Edited for detail.
Wow, very helpful responses! Thanks much Torontonian, L.A.B. and Timewarp.
Didnt look to me like i would be able to get the Mk3 bonded type installed without removing the primary, but glad to hear its possible. Not too long ago I installed a CNW starter and belt drive and new alternator stator, so i didnt particularly want to disrupt all that now that its all working so well.
Should have done the rear iso back then but….
Thks again and i welcome any more info/comments on this insitu rear iso topic.
 
This was the front replaced first (Remove the housing pivoting the rear) then the rear done in the frame with the front bolt back in place.
The Iso installed with a pushing corkscrew action.

The front is easier on the centre stand because the engine will pivot up easily on the rear Isolastic more so if the airbox is in place, the filter out on a ham can (?) and the two low and one upper 1/4" bolts on the plastic airbox so it can move rearward with the carburetors still attached.
The front Isolastic housing will come up from the bottom with the ends removed and engine rotated, lifted above the frame lugs the discs and threaded caps can then be installed.
Pushed from the T/S the D/S can be installed with the grubscrew but not with excess preload (perhaps) if the outer rubbers are not quite in the right spot, the T/S can then be fit and the housing dropped, 3/8" bolts fit then the engine rotated to fit the front 1/2" bolt.
The rear can then be rotated down and done in place, I lowered the engine on a floor jack with wooden protector based on that pic but wonder if the rear of the frame could be lifted as another option.
Or something like that, I read it was all but impossible or tricky but did not find that . Slow and steady.

View attachment 84248


If the bike needs new Isolastics it will most likely need other area's addressed also.

The Vernier adjustment is easy based on the brand and thread class which means all that needs doing is add rotation which will reduce once the fastener is torqued to spec.
I forget offhand but with the RGM, 3 clicks maybe which will reduce to two (0,008 / 0,009")

Edited for detail.
Sorry, but whats T/S and D/S? Appreciate the help!
 
Sorry, but whats T/S and D/S? Appreciate the help!

Timing and Drive side.

I put the front Isolastic unit back in today.
D/S end cap with the locking grub screw first then the T/S (adjust side) second.
The boots needed a wipe with Pledge to get them in place which can be a bit fiddly.
 
Timing and Drive side.

I put the front Isolastic unit back in today.
D/S end cap with the locking grub screw first then the T/S (adjust side) second.
The boots needed a wipe with Pledge to get them in place which can be a bit fiddly.
Nice tip on the Pledge...:cool:
 
"Pls prove this wrong" -- OK, it's wrong. not that i'm any kind of Norton expert, but I just finished the Mk3 rear iso with the engine in frame and the primary chain case assembled and in place. it was a bit tricky, but very doable. one thing I found is having the end cap, Teflon washer and adjuster in place, as the one piece iso mount is pushed in from the right side, while screwing on the adjuster. with the adjuster screwed in all the way, push the center iso shaft max left. this allowed me to install the RH end cap, Teflon washer, and abutment. getting the RH abutment in place was a tight fit, but all it took was a slight tap with a plastic mallet. I backed off the adjuster several turns as i set the RH abutment and secured with a setscrew. i positioned the adjuster, and backed off 1-1/2 holes per the instructions (reset to .010" per LAB's suggestion). the way I did it was a bit different from the forum instructions posted by Michael Taglieri, since my primary chain case was installed. I had to assemble everything from the right vs the left as the instructions stated. I also referenced instructions from RGM Motors and the kit instructions from Andover Norton. BTW, my 74 Mk2 is pretty much just the frame, front and rear wheel, and engine and gearbox. the oil tank, horn, oil filter assembly, and battery tray assembly were all removed before hand, as well as the head steady mount. my engine and gear box assembly was pretty much supported by the center stand, and I lifted and supported the frame (from the rear) with an engine hoist. when I got the gaiters installed, lowered the frame, and all it took was a little wiggle-giggle and the rear iso center stud slid into place. I was kind of sweating this job, but honestly, it was easier than I thought. hope this helps....

next task at hand, front mount.
Got my parts and tore into the bike pretty much as u and LAB described.
Have good enuf access to the tube from the RH(timing side) side. The new Mk3 bonded setup has iso rubbers a full 0.120” larger dia than the id of the tube.
I have the right lube and was able to “work in“ the first one but it looks much more difficult for the second one since u cant work the shaft up/down/around near as much with the shaft nearly fully engaged. Before i put it in the freezer and cut leads on the rubbers and the end of the steel tube, would u pls verify that feeding it from the RH side the first rubber in is the one on the end that threads into the “adjuster” which has the little holes for the “tommy bar”. And the second end that ends up on the timing side is the one that screws onto the end piece with the threaded holes to accept the grub screw. Is that right?
Thks, Tom
 
I have the right lube and was able to “work in“ the first one but it looks much more difficult for the second one since u cant work the shaft up/down/around near as much with the shaft nearly fully engaged.


I don't remember the second one being all that difficult. Have you tried inserting the stud into the tube and then using that as a lever to work the rubber around while easing it into the cradle tube with a blunt tool or thumbnail?

would u pls verify that feeding it from the RH side the first rubber in is the one on the end that threads into the “adjuster” which has the little holes for the “tommy bar”. And the second end that ends up on the timing side is the one that screws onto the end piece with the threaded holes to accept the grub screw. Is that right?

Feeding it from either the right or left side shouldn't make any difference. The threaded adjuster is normally at the LH (primary side) of the tube on the rear Iso. (with the fully threaded tube end) and the fixed abutment on the RH end (with the short unthreaded end section).
 
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