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Thread: knucke frame

  1. #1
    Join Date
    Feb 2010
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    ***an
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    38

    Default knucke frame

    hi,
    please advise.
    any difference between 37 and 38 frame?

  2. #2
    Join Date
    Jul 2002
    Location
    North Hills, CA and Pine Grove, CA
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    Default

    Yes. One easy thing is the backup nuts on the tool box mount. 37 are rectangular and 38 are round. 38 has closed brake stay while most 37 have the end cap welded on, if they even have one.
    Palmer's new book has all the details.
    Be sure to visit;
    http://www.vintageamericanmotorcycles.com/main.php
    Be sure to register at the site so you can see large images.
    Also be sure to visit http://www.caimag.com/forum/

  3. #3
    Join Date
    Feb 2010
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    ***an
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    Default

    Quote Originally Posted by Chris Haynes View Post
    Yes. One easy thing is the backup nuts on the tool box mount. 37 are rectangular and 38 are round. 38 has closed brake stay while most 37 have the end cap welded on, if they even have one.
    Palmer's new book has all the details.
    ok, thanks!!!

  4. #4

    Default

    37 has a 7/8" upper strut and 38 has 1" strut ( behind gas tanks) ,,,,
    the welded brake stay can be very well done and hard to decide if its added or if it is a forging.
    Last edited by 3_7/16bore; 04-07-2017 at 07:38 AM. Reason: Spelling

  5. #5
    Join Date
    Apr 2008
    Location
    Upper Yarra Valley, Victoria. Australia
    Posts
    826

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    3 differences in the foundry marks for 1937 neck forging
    1/2" square for the first 37 VINs
    After that they reduced the foundry mark to about 5/16" square
    Then 5/16" square with number 2 for high VIN.
    The number 2 revision neck had a larger spigot for the backbone brace. These necks started with 7/8" tubes with a sleeve over the tube to take it up to the 1" hole.
    Then they had a 1" tube. All of these tubes were braised to the backbone.

    All 37 frames had the narrow seat post cross braces.
    Steve Little
    Upper Yarra Valley. Victoria.
    Australia.
    AMCA member 1950

  6. #6
    Join Date
    Jul 2002
    Location
    North Hills, CA and Pine Grove, CA
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    Default

    Quote Originally Posted by 3_7/16bore View Post
    37 has a 7/8" upper strut and 38 has 1" strut ( behind gas tanks) ,,,,
    the welded brake stay can be very well done and hard to decide if its added or if it is a forging.
    Early '37 is 7/8, Mid year became 1".
    Be sure to visit;
    http://www.vintageamericanmotorcycles.com/main.php
    Be sure to register at the site so you can see large images.
    Also be sure to visit http://www.caimag.com/forum/

  7. #7
    Join Date
    Apr 2008
    Location
    Upper Yarra Valley, Victoria. Australia
    Posts
    826

    Default

    Braised front engine mount for 37. Electrode welded front engine mount for 38. Braised top engine mount 37. Electrode welded top engine mount for 38. Once upon a time I could rattle all this info in one shot. I will probably remember something else as it bubbles up.
    Steve Little
    Upper Yarra Valley. Victoria.
    Australia.
    AMCA member 1950

  8. #8
    Join Date
    Feb 2010
    Location
    ***an
    Posts
    38

    Default

    thanks you all!!

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