Looking for help on a front end swap!
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Thread: Looking for help on a front end swap!

  1. #1
    Member Roca709's Avatar
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    Looking for help on a front end swap!

    I currently have a 1982 Honda CM450 cafe racer project on the go. I also have the front end off a 2005 Ninja 636. I'm looking for some specs on both of the front ends so I can swap. Any help and advice is greatly appreciated as I'm a complete newbie. Thanks in advance.

  2. #2
    Senior Member oupa's Avatar
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    Are you planning to switch out the whole front end (triple clamps and forks) or are you just talking fork legs? Either one should be a matter of simple measurements (will it fit?) unless you're planning radical changes.

    That said, I am not PERSONALLY familiar enough with either to know even general comparisons without seeing them, but changing the length of the fork can have undesirable consequences on trail, which in turn can have very undesirable effects on handling. There is much more at stake than aesthetics! ...not much help I know, but your question looked lonely.
    "They're not like cars with a body that rusts out in a few years. Keep them tuned and overhauled and they'll last as long as you do. Probably longer." - Robert Pirsig

  3. #3
    Senior Member Alan F.'s Avatar
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    A complete front end swap will be simplest. Have a look at: https://www.allballsracing.com/index.php/forkconversion for a set of tapered roller head bearings to make that front end fit your bike.

    Also for some tech that might be fun, have a look at the link in my signature line below.
    oupa likes this.
    CB250 Nighthawk projects 92,93,92.
    81 CM400C Sold
    93 CB750 Nighthawk Sold
    73 CB750K3 Long term project stuck in the 'parts collecting stage.'
    Fork Swap info: http://sites.google.com/site/alansdocuments/

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  5. #4
    Super Moderator longdistancerider's Avatar
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    Huge list of possibles but NOT Ninja 636
    Jim O'Brien
    1979 CM400T "road bike" modified for travelling
    1978 CB400T1 restored
    1972 CL350 nuts and bolts restore in progress


    https://www.hondatwins.net/forums/22...d-attempt.html and https://www.hondatwins.net/forums/1-...r-attempt.html
    Road Trip https://www.hondatwins.net/forums/11...here-i-go.html or "where's Jim now?"
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  6. #5
    Senior Member Alan F.'s Avatar
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    Quote Originally Posted by longdistancerider View Post
    Huge list of possibles but NOT Ninja 636
    Perhaps with some careful measurements you can call them up to see what the roadblock is. Also if they do have a bottom or top bearing that fits, and steering stem length is long enough... a bearing cup could be fabricated to adapt the other bearing to the steering stem.
    CB250 Nighthawk projects 92,93,92.
    81 CM400C Sold
    93 CB750 Nighthawk Sold
    73 CB750K3 Long term project stuck in the 'parts collecting stage.'
    Fork Swap info: http://sites.google.com/site/alansdocuments/

  7. #6
    Senior Member Alan F.'s Avatar
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    This thread has photos of the 636 stem with a tape measure showing where all the threads begin and end, maybe this is useful?

    https://www.customfighters.com/forum...ad.php?t=58680


    From the allballs list:

    the 636 bearing sizes are:
    ID OD WIDTH TOP BEARING ID OD WIDTH BOTTOM BEARING
    35 55 14 99-3523-5 35 55 14 99-3523-5


    And the CM450 sizes are:
    ID OD WIDTH TOP BEARING ID OD WIDTH BOTTOM BEARING
    30 48.5 15 99-3541-5 30 50 14.25 99-3512-5


    To fit that 636 triple into a CM450 frame you'd need a: top bearing with....... an ID of 35mm and an OD of 48.5
    and a: bottom bearing with...an ID of 35mm and an OD of 50mm


    OK, lets go back to AllBalls.com https://www.allballsracing.com/media...gSizeChart.pdf

    They don't offer these sizes so it's time to get creative, you could probably have a local machine shop make up some ball bearing races and have them heat treated for a surprisingly low price, Your Mileage May Vary, but it may be your best choice all in all.

    Or we can have a look at other sources of tapered roller bearings for a close match.

    Lets convert to inches now:

    Top bearing:
    35mm = 1.377" ID
    48mm = 1.889" OD
    15mm = .590" 'width' of the CM450 top bearing.


    Bottom bearing:
    35mm = 1.377" ID
    50mm = 1.968" OD
    14.25mm = .561" 'width' of the CM450 bottom bearing.



    Nope, no close matches. I understand AllBalls buys certain size bearings and has them custom ground to the appropriate size for Motorcycle applications, That's why there are no close matches out there. If you wanted to have a custom steering stem made, perhaps an off the shelf bearing could be found to fit.


    I do not endorse using these, they're the wrong kind of bearings, they're designed for axial loads not radial loads, and if used in this manner they WILL FAIL spectacularly, use at your own risk!
    Deep groove ball bearing
    35BD4820T1XDDUM-01-NSK - 35x48x20 mm
    https://www.123bearing.com/bearing-3...DUM-01-NSK.php
    Deep groove ball bearing
    3BG05S7G-2DL - 35x50x20 mm
    https://www.123bearing.com/bearing-3BG05S7G-2DL.php

    CB250 Nighthawk projects 92,93,92.
    81 CM400C Sold
    93 CB750 Nighthawk Sold
    73 CB750K3 Long term project stuck in the 'parts collecting stage.'
    Fork Swap info: http://sites.google.com/site/alansdocuments/

  8. #7
    Senior Member Alan F.'s Avatar
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    I think your best two options would be:

    1) to look into having some ball bearing races made up to fit the existing 636 triple to the CM450 frame neck. Provided the 636 steering stem is a good fit for the frame neck.


    Or most likely your best bet:

    2) look into having a bushing made up that will fit the CM450 steering stem into the 636 lower triple. One simple part to fabricate, grind the weld from the bottom of your CM450 lower triple and press the steering stem out, weld on the bushing and press the stem with adapter bushing into your 636 lower triple, then bolt it up to your CM450 using AllBalls bearings made for a CM450, figure out your steering stops so your 636 forks don't hit your tank, and go from there.


    Cheers!
    CB250 Nighthawk projects 92,93,92.
    81 CM400C Sold
    93 CB750 Nighthawk Sold
    73 CB750K3 Long term project stuck in the 'parts collecting stage.'
    Fork Swap info: http://sites.google.com/site/alansdocuments/

  9. #8
    Senior Member HamHock's Avatar
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    sell the 636 and buy a different front end? VF500 if a bolt on.
    Quote Originally Posted by outobie View Post
    make it ugly so you don't feel bad about crashing. Ugly bikes are MUCH faster then pretty ones
    NC01 - Hamhock
    PC12 - Gone
    RC26 - Gone
    RC36/1 - Fast

  10. #9
    Senior Member Alan F.'s Avatar
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    How's that bike treating you Hammy?
    CB250 Nighthawk projects 92,93,92.
    81 CM400C Sold
    93 CB750 Nighthawk Sold
    73 CB750K3 Long term project stuck in the 'parts collecting stage.'
    Fork Swap info: http://sites.google.com/site/alansdocuments/

  11. #10
    Senior Member HamHock's Avatar
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    It's been out of commission for a while now. Plan is to install the original oil burning engine so I can get it back on the road while I do a full rebuild on the two parts engines I have.
    Quote Originally Posted by outobie View Post
    make it ugly so you don't feel bad about crashing. Ugly bikes are MUCH faster then pretty ones
    NC01 - Hamhock
    PC12 - Gone
    RC26 - Gone
    RC36/1 - Fast

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