1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.

Layshaft bearing

Discussion in 'Other Norton Motorcycles' started by baz, Nov 5, 2019.

  1. baz

    baz VIP MEMBER

    Joined:
    May 26, 2010
    Opened up an atlas gearbox to check condition and found this bearing on the layshaft
    It's obviously a conversion but not the same as I have seen before
    Does anyone know if these are good?
    Cheers IMG_20191104_212923266.jpg
     
  2. Burgs

    Burgs VIP MEMBER

    Joined:
    Dec 14, 2013
    Hi Baz
    Not sure a roller bearing would be good or not, but generally for a roller bearing everything needs to be inline, and shaft no bend under load, on the other hand deep groove ball bearings can handle a little bit of both.
    If everything is inline and the shaft doesn't bend the roller would be better as the load carrying capacity is greater, but more costly.
    The other thing is end loads/location, the roller no, DGB ok sort of, need to read a bearing manual for specific loads but they give good examples for reference.

    Burgs
     
    MichaelB likes this.
  3. baz

    baz VIP MEMBER

    Joined:
    May 26, 2010
    Yes I see what you mean about alignment
    If the bush the other end of the layshaft were worn this could pull the roller out of alignment?
    Cheers
     
  4. mdt-son

    mdt-son

    Joined:
    Jan 19, 2012
    The layshaft is subjected to bending and twisting due to the force couple acting at the gear wheel flanks. In addition, bending of the mainshaft may affect the layshaft by shifting the action line at the gear wheels. Bearing resilience and clearance will increase deformation also.
    Fitting a roller bearing may have been an attempt to impose a clamping condition at the layshaft's end support. This will not succeed. Rollers will misalign and wear will increase rapidly as line of contact becomes point of contact.
    The best bearing arrangement is found in the AMC racing gearbox as used on the Manx, 7R and G50. Due to the absence of the K/S, the inner cover supported the layshaft by a ball bearing. I believe the standard inner cover can be machined to accept a ball bearing for those wanting to abandon the K/S. Otherwise, the racing inner cover has (had?) p/n 050125 with RGM.

    -Knut
     
  5. Tornado

    Tornado VIP MEMBER

    Joined:
    Dec 5, 2017
    Mick Hemmings, in his gearbox rebuild d vd, recommends a DGB bearing on the layshaft drive side instead of the more popular roller for the reasons stated above. Having recently looked at an AMC layshaft in detail and seeing the grooves cut into the shaft at the 90 degree changes in diameter for oilways, I can see why they are prone to breaking under loading. I hear there are such things as 90 degree radiused shafts being made. Might me custom jobs or sourced? Just for racing?
     
    Last edited: Nov 6, 2019
  6. Fast Eddie

    Fast Eddie VIP MEMBER

    Joined:
    Oct 4, 2013
    Norman White uses roller bearings for the layshaft.
     
  7. baz

    baz VIP MEMBER

    Joined:
    May 26, 2010
    That's interesting does he also use a bearing in place of the bush/kickstart shaft would you know?
     
  8. Fast Eddie

    Fast Eddie VIP MEMBER

    Joined:
    Oct 4, 2013
    I don’t know Baz. He rebuilt my box, but I’ve not looked inside since !
     
  9. baz

    baz VIP MEMBER

    Joined:
    May 26, 2010
    Ok I'm guessing if you still have a kickstart you still have the bush
    Cheers
     
  10. marinatlas

    marinatlas

    Joined:
    Nov 4, 2007
    RGM was supplying a needle bearing for the kickstart instead of the bush , you should ground the layshaft end to fit , tho it still remains some evidence of the previous scroll marks !!, it seems they do not supply it anymore ?
     
  11. comnoz

    comnoz VIP MEMBER

    Joined:
    Dec 10, 2008
    They don't supply it anymore because the shaft was not hard enough to live with needle bearings running directly on the shaft. It was a neat idea that ended up destroying the layshaft after some miles.
     

Share This Page