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74 Mk2 - rear iso mount

Discussion in 'Norton Commando Motorcycles (Classic)' started by joe czech, Aug 22, 2019.

  1. joe czech

    joe czech

    Joined:
    Feb 21, 2019
    finally got around to removing the rear engine mount center stud. check out these ios mounts. you might say, just a little off center -

    [​IMG]

    [​IMG]

    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.
     
    Last edited: Aug 22, 2019
  2. dynodave

    dynodave

    Joined:
    May 28, 2003
    Looks like lots of centerstand time/sag.
    If you pull them out, silicone lube them up, and rotatate 180 dggrees, reinstall, you will get another 20 years.
     
  3. joe czech

    joe czech

    Joined:
    Feb 21, 2019
    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.
     
    Last edited: Aug 23, 2019
  4. dynodave

    dynodave

    Joined:
    May 28, 2003
    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
     
    Last edited: Aug 22, 2019
  5. Onder

    Onder

    Joined:
    May 11, 2010
    And there is a source for "early rubbers"?
     
  6. Tornado

    Tornado VIP MEMBER

    Joined:
    Dec 5, 2017
    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....
     
  7. joe czech

    joe czech

    Joined:
    Feb 21, 2019
    "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.
     
    Last edited: Aug 25, 2019
    Tornado likes this.
  8. L.A.B.

    L.A.B. Moderator VIP MEMBER

    Joined:
    Nov 20, 2004
    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.
     
    Last edited: Aug 22, 2019
  9. Tornado

    Tornado VIP MEMBER

    Joined:
    Dec 5, 2017
    Very cool! And you'll find the front iso work a piece of sweet coconut cake....
     
  10. joe czech

    joe czech

    Joined:
    Feb 21, 2019
    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....
     
    Last edited: Aug 24, 2019

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