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Thread: VL fork on big twin frame

  1. VL fork on big twin frame

    Hello, i am needing some information on the install of the VL fork with 1 1/8 stem on a big twin knuckle frame.

    A really good machinist made new frame cups that fit the frame and the stem pass thru. We found timkin bearings that will fit the shaft and are the most narrow available in width of bearing and race. The problem is using the timkin we end up with a overall height of the cup/bearing that leaves very few threads on the VL fork stem to put the nut on.

    Yes race is removed from bottom of fork, the frame cups cannot get thinner.

    I did see on-line a shop in California shows a neck cup conversion kit that is out of stock, they show in photos and info a double shielded bearing saying load is 2,150 etc, i assume this is a ball bearing?

    Can anyone here help me with what type of bearing to use, where to buy. can we go to a standard 1 1/8 bore ball bearing in our custom cups?? this would be much more narrow but will it take the load of a fork??

    Does anyone know how the old timers installed these forks, sometimes you see old black and white photos with VL forks on a old knuckle bobber...what parts did they use??

    Thank you for any help or insight.

  2. #2

    Re: VL fork on big twin frame

    Could've saved yourself a lot of trouble by going the other way and having a 1-inch stem machined for your VL fork, of EL/UL length. It's been done many times before. WILL easily carry the load. The 1 1/8" bearing was H-D's unnecessary overkill.

    Edit: And Welcome to the asylum!
    Hee hee: http://www.caimag.com/forum/showthre...ight=HANDSHIFT
    Last edited by Sarge; 06-11-2019 at 10:11 AM.
    Sarge, Gerry Lyons, Fla.
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  3. #3

    Re: VL fork on big twin frame

    Tap the center of the neck stem (very carefully to keep it straight) and use a thrust washer to apply the load against the bearing if you want something that will work. I ran into the same issue with my J fork conversion to Timkens.
    27 JD (almost)

  4. Re: VL fork on big twin frame

    Thank you for the replys.
    Sarge: changing the stem looks like much more "surgery" than i want to do on the VL fork.

    WHP: the stem has threads, i am not quite sure what you mean. Are you saying use the timkin bearings, then make spacers above the top bearing, then use a thru bolt to push down the top clamp to give pressure to the bearing. If that is what you are meaning what would keep the bolt from backing out? since it would be semi tight.

    Please explain more.

    I assume a ball bearing would not work?

    Thank you.

  5. #5
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    Re: VL fork on big twin frame

    I used the VL cups and machined the OD to Fit the Knuckle frame, I was a bit concerned with thickness but the frame allows a big radius on the cut so there was never an issue. I'm not that big a fan of Timken conversions as the stock balls work just fine and there was no stack height issues so all the hardware worked as originally fitted. That bike is still out there on the road last I heard and I did that one in '88.
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  6. #6

    Re: VL fork on big twin frame

    Quote Originally Posted by handshifter13 View Post
    Thank you for the replys.

    WHP: the stem has threads, i am not quite sure what you mean. Are you saying use the timkin bearings, then make spacers above the top bearing, then use a thru bolt to push down the top clamp to give pressure to the bearing. If that is what you are meaning what would keep the bolt from backing out? since it would be semi tight.

    Please explain more.

    Thank you.
    You're correct. Overcoming stack height issues with a spacer above the top bearing and tightening that bolt to obtain the correct bearing tension.

    You'll have to rig up something to keep the bolt in position. I use a set screw into a slight indent that I put into the fork to keep my bolt in position.

    J forks do not have threads on the ID of the stem, probably because they do not have steering dampers like later forks. Hence the threading comment... I don't have a VL fork in front of me to take a look at unfortunately.

    Will
    27 JD (almost)

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