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Rear axle nut thread size?

Discussion in 'The Garage' started by Mp219, Mar 23, 2016.

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  1. Mp219

    Mp219 XS650 Member

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    Does anyone know what the rear axle nut thread side is. Trying to see if I can find a locking castle nut for it, to eliminate the use of cottor pin.
     
  2. XSLeo

    XSLeo XS650 Guru Top Contributor

    I wouldn't. The lock nut can wear the threads out quickly. And as often as that nut gets loosened for chain adjustments and tire changes the threads wear fast enough.
    Oh, I don't know the size right off. Can't you measure yours?
    Leo
     
  3. Mp219

    Mp219 XS650 Member

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    At work, so I took the lazy route and posted this to see if anyone knew. I use them on all my bikes, never had a issue with it wearing out the threads on the axle it self.
     
  4. mrtwowheel

    mrtwowheel Honda Etched On Brain Top Contributor

  5. 5twins

    5twins XS650 Guru Top Contributor

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    The rear axle has a 20mm diameter so I imagine that would be the thread size as well. I just dressed one with buggered threads using a metric thread file and the pitch was 1.50. I love that tool, lol. The axle nut would barely go on one or two threads when I started. Now it spins on completely smooth as silk.

    I have also switched to the hitch pin style cotters, on my wheels and many other places that require a cotter pin as well .....

    [​IMG]

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    Last edited: Oct 13, 2019 at 9:01 AM
  6. 53xs650

    53xs650 XS650 Enthusiast

    The rear axle on my 1980 is only 18mm where threads are. In my opinion I would be very careful about using hitch pins where cotter pins go, I have seen too many fall out on different equipment over the years. They are also too easy for someone to walk by and pull out.
     
    lakeview likes this.
  7. 5twins

    5twins XS650 Guru Top Contributor

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    I check mine often and have yet to lose one. If you'll notice, I set the rear axle so the shock mount blocks the pin from popping out. But then, how do I get it out when I need to? You simply rotate it so it's horizontal and it slips right out.
     
  8. 53xs650

    53xs650 XS650 Enthusiast

    Like you you said, if it gets horizontal it slips right out. I am sure You check yours often, But just wanted to point out that they do fall out and if it happens going down the road it could cause a big problem.
     
  9. mrtwowheel

    mrtwowheel Honda Etched On Brain Top Contributor

    Cotter pins on the axle is a "fail-safe" design, developed by NASA and the Nipponese Space Agency. There are no cotter pins on Russian motorcycles, not even a hitch pin clip.

    Scott
     
    Last edited: Mar 24, 2016
  10. TwoManyXS1Bs

    TwoManyXS1Bs BBQ Hunter Top Contributor

    I thought that the original design for the cotter pin was designed by Dr. Rudolf Cotter in 1834.
     
  11. 5twins

    5twins XS650 Guru Top Contributor

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    My '70s BMWs have no cotter pins on the axles, no lock nut either, just a plain nut. And they're not even torqued very high, just about 25 ft/lbs.
     
  12. retiredgentleman

    retiredgentleman XS650 Guru Top Contributor

    I tend to agree with what 5twins is saying. I'm sure a hitch pin is more that safe for the rear axle. Even in the remote chance that the pin came out, the axle nut is not going to loosen.

    I use a regular cotter pin on my rear axle. Whenever I remove the cotter pin, it always just comes out with my fingers. In other words, the nut has never loosened enough to put pressure on the cotter pin. In my experience, large nuts like on the rear axle do not loosen up by themselves. Once the nut is tight, there is no rotational force large enough to loosen the nut.

    The only bolts/nuts I've noticed that back off are 6 mm size threads or smaller.

    Having said that, I will always use a cotter pin where there are castlelated nuts. To me that is just safety in depth logic. While I believe it would be very rare for an axle nut to loosen, the cotter pin gives a second barrier.

    BMW is obviously very confident that axle nuts will stay tight.
     
  13. mrtwowheel

    mrtwowheel Honda Etched On Brain Top Contributor

    In the case of catastrophic bearing melt down..........definitely, the axle nut will loosen.

    Scott
     
  14. retiredgentleman

    retiredgentleman XS650 Guru Top Contributor

    Will you share your experience with the details of this happening?

    If a bearing destroys itself while you are riding, I suspect you would have considerable warning, in the form of noise and smoke, at which time you would stop the bike. A loose axle nut would be a moot point, and the least of your problems.
     
  15. mrtwowheel

    mrtwowheel Honda Etched On Brain Top Contributor

    I've seen many bearings burn up with a temperature that would melt metal, and a temperature fit for welding steel. Early retired non-union factory worker for automotive suppliers, we're the ones that really build your cars, assembly is just....well, just assembly. I've seen many bearings destruct before my eyes, I don't think you'd even notice it on a bike.

    Scott
     
  16. retiredgentleman

    retiredgentleman XS650 Guru Top Contributor

    I'm interested in the details of what you are saying, but this thread was about motorcycle rear axles. Are you perhaps talking about an industrial setting, where the equipment is run 24/7, year after year?
     
  17. Team Junk

    Team Junk XS650 Addict

    Here is a rear bearing motorcycle story. Sometime in the early 80's at Daytona my buddy was lying in 6th when he comes into the pits with 2 laps to go. He yells that something is wrong in the rear. I check and everything is where it's supposed to be. I tugged on the back wheel and it is attached. I sent him back out and he finishes. We put the bike on the stand as I notice smoke coming out of the rear hub. I grab the back of the wheel and there is at least 3/4 inch play. The left bearing had totally disintegrated and the inner race was welded to the axle but the cotter pin came right out.
     
    TwoManyXS1Bs, mrtwowheel and gggGary like this.
  18. madmax-im

    madmax-im Yamaha...Go your own way... Top Contributor XS650.com Supporter

    My bike has a hitch pin on the rear axle nut...it is easy to pull it out .. I am undecided about wether i should keep this or revert back to a cotter pin...What is the consensus?
     
  19. madmax-im

    madmax-im Yamaha...Go your own way... Top Contributor XS650.com Supporter

    After re-reading this I think i will revert to cotter pins...
     

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