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  1. #1

    Default Girder front end

    I recently installed this girder but the spring is bending how do I adjust to make it work Click image for larger version. 

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  2. #2
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    it should have a spring over shock absorber NOT just a spring....

  3. #3

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    There’s no mount for a shock the front end is from the late 60 early 70

  4. #4
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    The spring mounts at each end of the spring must be free to pivot as the fork moves. You have one or both mounts pinched or restricted in some way.

    Jim

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    I got a similar girder,check this one out together.
    Attached Thumbnails Attached Thumbnails IMG_0873.jpg   IMG_0875.jpg  

  6. #6
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    With that girder install, your neck length between upper and lower tree is too long.

    You want to have the distance between the upper and lower pivot points on the trees, to be the same (equal) as the distance between the upper and lower pivot points on the legs.

    This will result in the linkages, the upper linkage and the lower linkage, to be parallel to each other.

    It doesn't matter if the linkages are level, or horizontal, as the rake will affect that. The upper and lower linkages need to be parallel to each other for best performance.

    Remove or reduce the thickness of the spacers between the trees and the bearing cups.
    We can't see what you have on top due to the photo, but the lower section looks to have a thick spacer between the bearing cup and the lower tree of the girder.

    Think of it like this; If you were to remove the linkages, the legs should fit right onto the upper and lower tree pivot points.

    Try that first to see how it affects the spring.

    Share a few more photos to help with identifying that girder, unless you already know.

  7. #7

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    Tzlee is right. Ditch that spacer on the bottom. Looks like then the plates/ links will be parallel. After that the next problem will probably be the stem is to long.
    Last edited by flatman; 1 Week Ago at 9:51 PM.

  8. #8
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    Not all girders had pivoting spring mounts. Durfee girder, one of the strongest ever built, has solid (fixed) spring mounts at each end of the spring:

    Click image for larger version. 

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    Click image for larger version. 

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    http://durfeegirder.com/about.html


    Cycle Shack had fixed top and bottom spring mounts:

    Click image for larger version. 

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    And, it does look like that spring is too long.
    Attached Thumbnails Attached Thumbnails girder, Santee with positive trailign.jpg  

  9. #9

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    I’m not familiar with modern, after-market girder forks in detail, but I do have experience of OEM units.

    Firstly, the geometry of the links in the OP is definitely wrong. The fork will not operate correctly like that. The spring also appears to be too long. This is probably related to the link issue - the fork stem appears to be too long for either the frame, or the girder blade. This is basic to the engineering design of the overall assembly.

    Secondly, most OEM girder forks had fixed spring mounts. This is the reason why they usually had springs with a pronounced “barrel” shape, ie the diameter was much smaller, too and bottom. The small diameter sections accommodated the flex from the (geometrically incorrect) relative movement of the mounts as the fork operated, and the larger section provided the actual spring effect. This is also basic engineering design - a jointed strut in compression is an inherently weak design, so by fixing the spring mounts, the fork is stronger and the geometric problems are accommodated in the small-diameter ends of the spring.

    The makers of the Durfee unit illustrated, clearly started out by copying an original, OEM fork. Why not? They were produced in large numbers in the 20s and 30s, Indian made a good-handling unit until the 1950s, why waste that development?
    Last edited by 45Brit; 1 Week Ago at 11:22 PM.

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