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Timing side main bearing shim on a MK3

Discussion in 'Norton Commando Motorcycles (Classic)' started by jimbo, Mar 19, 2019.

  1. jimbo

    jimbo VIP MEMBER

    Joined:
    Sep 25, 2004
    I am rebuilding my MK3 , it was rebuilt several years ago. I found no timing side main bearing shim(#15) as shown in the parts manual. I suppose I could assemble the crank into the cases, and measure the float. I do not remember why I did not install a shim last time, is there sometimes no need for one? norton bearing shim.jpg DSC09581.JPG
     
  2. Time Warp

    Time Warp .......back to the 70's. VIP MEMBER

    Joined:
    Dec 3, 2012
    Item 15 is only 0.003" thickness.
    If the main bearings are in the cases checking the float would not be much work but posts over the years have suggested a small correct amount of end float and quite a bit did not make much difference and did no harm to anything.

    If you had the bottom end down and had the time and inclinatiion to chase fairy's then why not.
    I machined dummy bearings and my own shims to suit (because I could)
    It would have to be a large amount of float to be a future problem most likely ?

    Could the oil pump drive gear have an effect on things from acceleration to deceleration might even be speculation.
    Maybe that is offset by the magnetism of the charging rotor.

    Where are the oil pump securing studs. ?

    IMG_5555.JPG
     
    Last edited: Mar 19, 2019
    nortriubuell likes this.
  3. L.A.B.

    L.A.B. Moderator VIP MEMBER

    Joined:
    Nov 20, 2004
  4. Atlas Commando

    Atlas Commando VIP MEMBER

    Joined:
    Feb 27, 2018
    I will sell my precision mounting bracket (bent from authentic metal) and dial indicator for a price substantially less than $700.... what, no takers?
    I didn't find any shims and when I checked the reassembly end float on the '72 it was .018" as I recall. It seems my crank was inadvertently built within specifications.
     

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    JimC and Time Warp like this.
  5. jimbo

    jimbo VIP MEMBER

    Joined:
    Sep 25, 2004
    I had bolts
     
  6. jimbo

    jimbo VIP MEMBER

    Joined:
    Sep 25, 2004
    .020" float found with new bearings( superblends both ends) gonna leave it alone. quote Jim Comstock in another thread ;


    None of them were shimmed from the factory.

    You can shim it if you would like but for normal use it isn't needed unless the end play get's over about .030. Jim




    DSC09640.JPG
     
  7. ashman

    ashman

    Joined:
    Jul 11, 2010
    My opinion is most over react to end float and these engines seem to like a bit of end float and after everything is bolted up and together the end float seems to be less, after 43 years my bottom end has been apart 3 times 2 times for complete rebuild and the third time to replace crank cases, I never worried about the end float and just put it back together, my motor has done a lot of hard miles from my youth of flogging it to high speed cruising to now still ride and push it hard even at 60 years of my age and for most of its life it was a everyday ride, my motor is not stock and has a few good things done to it and the only thing over size is the bore.

    Ashley
     
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  8. Atlas Commando

    Atlas Commando VIP MEMBER

    Joined:
    Feb 27, 2018
    Jimbo, your cases sure look clean! I wonder what you did to get them looking that nice?
     
  9. texasSlick

    texasSlick VIP MEMBER

    Joined:
    Jan 2, 2013
    I would like to know as well!

    Slick
     
  10. Time Warp

    Time Warp .......back to the 70's. VIP MEMBER

    Joined:
    Dec 3, 2012
  11. jimbo

    jimbo VIP MEMBER

    Joined:
    Sep 25, 2004
  12. texasSlick

    texasSlick VIP MEMBER

    Joined:
    Jan 2, 2013
    AW SHUCKS! I was hoping for a genie in a bottle!

    Slick
     
  13. jimbo

    jimbo VIP MEMBER

    Joined:
    Sep 25, 2004
    I consider it therapy:cool:, also I do an inspection while scrubbing.
     
  14. Atlas Commando

    Atlas Commando VIP MEMBER

    Joined:
    Feb 27, 2018
    No magic spray? Aw crap!
     

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