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Fitting rear Isolastic Rubber Bushes

Discussion in 'Norton Commando Motorcycles (Classic)' started by thunderbolt, May 21, 2018.

  1. thunderbolt

    thunderbolt

    Joined:
    May 16, 2016
    I am about to fit the bushes, etc to the rear iso. It has been suggested to use silicon grease to help get them in place. I have a can of SILICON SPRAY which appears to be a lubricant. Is this the same stuff (silicon grease) - can it be used or do I need to purchase some silicon grease?

    Thanks
    Don
     
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  2. Ron L

    Ron L VIP MEMBER

    Joined:
    Feb 27, 2004
    I use red rubber grease. Silicone sprays may contain solvents which could attack the rubber.
    [​IMG]
     
  3. thunderbolt

    thunderbolt

    Joined:
    May 16, 2016
    Sounds good Ron, I do have some PBR rubber grease (for brake boots) that I could use. That's a good point about solvents in the silicon spray - quite a possibility.

    Thanks
    Don
     
  4. RoadScholar

    RoadScholar VIP MEMBER

    Joined:
    Dec 28, 2008
    Silicone spray was made for rubber, even so it is not very useful when working with the ISO bushes, because it has no real staying power. The grease form is your friend.

    Also, when you have cleared the mounting tube, it needs to be really clean. If you try to introduce the new bush straight on you will need to be exceeding strong and long on frustration resistance. I recommend that you introduce the new bush at an angle, it makes life a bit easier. You will still have to deal with the frustration when trying to seat the last section of the bush. A socket that just fits around the center tube driven by a long piece of threaded rod, with a much larger socket on the receiving end may help you win the day.
     
  5. thunderbolt

    thunderbolt

    Joined:
    May 16, 2016
    Thanks roadscholar. Can you explain a little further the process with the threaded rod and sockets. Take it slow, I need time for my brain to absorb the process.

    Thanks
    Don
     
  6. thunderbolt

    thunderbolt

    Joined:
    May 16, 2016
    Advice needed:

    I decided to compare the overall length of the bushes and buffers assembled on the long iso bolt for the rear. I am using the iso bushes on the short tubes with the spacers between with the rubber buffers on them and circlips.

    When I measured the overall length of the old assembled bushes and buffers the distance was 1/16" shorter than the assembled new bushes and buffers. So the new setup is 1/16" longer than the old setup.

    Is this going to cause any issues when I assemble the new rubbers into the main rear tube of the gearbox cradle. Will there be a clearance issue.

    I am fitting new Mick Hemmings vernier adjusters both front and rear. I'm not sure how this setup works in practice. I guess I'm asking "seeing as the overall length is longer by 1/16" will the vernier adjusters be able to be backed off to allow for this or do I need to reduce the length of some of the spacers with the bushes and buffers on them".

    Thanks for any contributions.

    Cheers Don
     
  7. L.A.B.

    L.A.B. Moderator VIP MEMBER

    Joined:
    Nov 20, 2004

    Do you mean will the assembly now be too wide to fit the frame?

    If so, do the parts fit between the frame brackets when "assembled on the Iso bolt"?
     
  8. oldbeezer

    oldbeezer VIP MEMBER

    Joined:
    Nov 2, 2017
    I would like to add a couple of questions to this thread. what is the best way to remove the old iso? What is the best way to clean the tube? Could a ring compressor of suitable size be used?
     
  9. PeterJoe

    PeterJoe

    Joined:
    Dec 8, 2011
    Don,
    Are the isolastic mounts genuine Andover-Norton or are they some other brand? I recommend using genuine Andover-Norton rubber mounts. RGM units and others will transmit way too much vibration and you will not be happy. Also if they are genuine Andover-Norton mounts then I am sure that the lengths are correct.

    Mick Hemmings recommends using 850 Mark III gaiters however, I found that they did not work well especially the front one. It jammed really hard into the set screw and it just didn't look good. What I ended up using is the original gaiters. First I stretched the gaiters over a 1 1/8 inch wooden dowel (broom handle) and punched a 1/8 inch hole in the gaiters where the set screws go through. The reason I stretched the gaiters over the wooden dowel before punching holes is so that the hole would be round when stretched over the venier adjusters instead of oval. Here are a couple pictures of the finished installation:

    [​IMG]


    [​IMG]

    Also when I fabricated my battery tray I made it so that the front mounting bracket is removable so that you can remove the vernier adjuster for cleaning and servicing without having to remove the primary chain case. I would think that a standard battery tray could be modified in the same manner.

    When you finally wear out the nylon nub of your set screws (which won't be very long) you can use standard thread locking cup point set screws with 3/32 or 1/8 inch diameter nylon balls. I bought these from McMaster-Carr.

    I found that this setup works very well and the nylon ball actually conforms to the threads instead of being chewed up like the original setup. When you finally wear out these balls, they are replaceable and really inexpensive.

    I hope this is of some help,

    Peter Joe
     
    Nater_Potater and cliffa like this.
  10. cliffa

    cliffa

    Joined:
    May 26, 2013
    I have to admit that I have not fitted ISO's however I think if they are properly lubricated they are reasonably easy to get in. I think there is a YouTube video where they are pushed in with no tools. ( to the surprise of the owner).

    Old (or new) brake fluid is a very good rubber lubricant.


    Cheers,

    cliffa.
     
  11. thunderbolt

    thunderbolt

    Joined:
    May 16, 2016
    Great suggestion Les, Funny thing with the gearbox cradle and heaps of iso parts on the bench you get focused on those items and don't consider the freshly painted frame that is stored away in a lockup shed elsewhere.

    I already have the iso parts assembled on the rear iso bolt so just need to add the Mick Hemmings adjuster and do a trial fit on the frame.

    Thanks for drawing my attention to that.

    Cheers Don
     
  12. thunderbolt

    thunderbolt

    Joined:
    May 16, 2016
    Thanks Peter Joe, All the iso parts are Andover-Norton supplied by Mick Hemmings. The spacers with the buffer rubbers are a bit longer - only by .020" or so but it adds up with five individual pieces involved. I will try LABs advice later today for a correct fit.

    Thanks also for the info on grub screws and gaiters.

    Cheers Don
     
  13. RoadScholar

    RoadScholar VIP MEMBER

    Joined:
    Dec 28, 2008
    First: Removing the old ISO bushes. I have had them push out with minimal effort using just a 1/2" breaker bar, and I have had to struggle mightily and resort to using a hydraulic press. The difference is rust which comes and grows with poor storage and excessive exposure to water kicked up by the tires, a lot of which contains salt, especially in the "rust belt".

    Second: Cleaning the tubes. There are countless ways to clear the tubes from drill mounted wire brushes to bead blasting to brake hones. Your imagination and wallet are good guides. Whether you paint or coat or leave bear the interior is up to you.

    Third: The threaded rod and sockets. Any hardware store sells threaded rod, a 3/8" piece will fit easily through the center of the ISO bush, purchase standard nuts (3) and large washers. The issue here is getting the last large rubber donut into the tube; if your tube is mirror smooth it may just "pop" in, assumes silicon grease is utilized. If you are not so lucky place a socket on the protruding end that fits over the central, but is smaller than the ID of the tube. On the receiving end select a socket that will butt against tube. Insert the threaded rod, washers and spin on the nuts; good idea to lock two nuts together on the protruding end. Hold the two nuts locked together by the outer nut, turn the single nut on the receiving end and the ISO mount will be drawn right in. You may have to go past the set point because the formerly protruding end's bush will become concave. Once the bush is in, and past it's set point, reverse the process which will flatten the concave bush and bring the ISO mount to the correct set point. Yu can do this without the threaded rod if you have a hydraulic press handy; you'll still need one socket.

    I use, and offer kits with stainless steel end caps, be aware that there is a correct left and right side to the new bush, so install it once and install it right (instructions included). The set screw (grub screw) is for the stationary side so you shouldn't need to punch a hole in the gaiter; set it and forget it. Having the set screw available may offer you additional options, I can't say.
     
  14. Tornado

    Tornado VIP MEMBER

    Joined:
    Dec 5, 2017
    What are the steps needed to perform rear ISO replacement with minimal dismantling of bike/engine/tranny, if at all possible ?
     
  15. oldbeezer

    oldbeezer VIP MEMBER

    Joined:
    Nov 2, 2017
  16. thunderbolt

    thunderbolt

    Joined:
    May 16, 2016
    One more quick question. I notice the rear through bolt has a longer thread on one end. Can someone tell me which side of the bike the long thread should go? I could work it out I guess but it's easier to ask.

    Thanks Don
     
  17. thunderbolt

    thunderbolt

    Joined:
    May 16, 2016
     
  18. thunderbolt

    thunderbolt

    Joined:
    May 16, 2016
    I have fitted the iso rubbers and the metal centre piece of the rubbers are outside the cradle tube by a couple of mm. Is this normal?

    When I fit the bronze washer and end collar there is room for another bronze washer to go in there.

    Thanks Don
     
  19. RoadScholar

    RoadScholar VIP MEMBER

    Joined:
    Dec 28, 2008
    The ISO's central metal tube should be equally spaced on both side of the larger "container" tube, unless the instructions you received with the parts say otherwise. My ISOs have, essentially, 3 pieces on each side: tube end cap, PTFE washer and outer (screw on) cap. The central ISO mount metal tube should protrude a bit on each side as it should butt up against the frame gussets and needs to provide a home for the other 6 pieces.
     
  20. L.A.B.

    L.A.B. Moderator VIP MEMBER

    Joined:
    Nov 20, 2004
    As I understand it, Don has the Hemmings adjuster kit not the vernier conversion kit with the 'long' threaded tube.

    Does that include the (06-0685) end caps?



    With the Hemmings adjuster in position can the outer collar be screwed inwards far enough to touch the bronze washer?
     

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