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Board Trackers and Vintage Motorized Bicycles Vintage enthusiasts share your board trackers and other vintage motorized bicycles ideas, builds and replicas here

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  #11  
Old 11-28-2016, 08:51 AM
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wret wret is offline
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Default Re: What vintage fork will fit a 3-inch tire?

I had some time to play over the holiday/long weekend. These came out pretty close to what I was going for.
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File Type: jpg rockers.jpg (103.4 KB, 21 views)
File Type: jpg leaf spring.jpg (164.4 KB, 21 views)
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  #12  
Old 11-28-2016, 09:04 AM
curtisfox curtisfox is offline
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Default Re: What vintage fork will fit a 3-inch tire?

AWESOME! What did you use for springs? That's really going to look nice...........Curt
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  #13  
Old 11-28-2016, 09:45 AM
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Default Re: What vintage fork will fit a 3-inch tire?

Looks super Wret. Really heavy duty rockers. What forks did you decide to run?
Rick C.
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  #14  
Old 11-28-2016, 10:24 AM
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Default Re: What vintage fork will fit a 3-inch tire?

Vintage Ski-doo springs. I couldn't find any contemporary springs that were thin enough and wide enough. These seem just about perfect. I now might be able to give a little advice on spring bending if anyone wants to try something like this.

I found there are a couple guys selling some fairly realistic vintage/replica truss forks. Apparently there is not a huge market for them though and it seems there are not many in the pipeline. If I kept searching and pestering the vendors I might actually get my hands on one. Meanwhile, after considerable thought, I've decided that constructing the fork itself might be within my skill set after all. I just need to borrow a better welder.

One possible dilemma I haven't worked out in my head yet: how does one flatten the fork tubes? Bike frame component suppliers sell straight conical fork tubes. Leaving them round wouldn't really bother me but I'm trying to keep this as authentic as possible.
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  #15  
Old 11-28-2016, 10:37 AM
curtisfox curtisfox is offline
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Default Re: What vintage fork will fit a 3-inch tire?

Yes would really like to know how you bent the springs? flaten fork tubs in vice Big one ) or hydraulic press....................Curt
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  #16  
Old 11-28-2016, 11:23 AM
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Default Re: What vintage fork will fit a 3-inch tire?

This may seem obvious but the shape of the bend in the spring is highly dependent on the form you bend it around. A good blacksmith might be able to do this over an anvil but my practice bend on a trailer spring was not pretty.

I was working on setting up a bending jig using two straight hardwood boards I had laying around when it occurred to me the parallel sides of my harbor freight pipe bender would be nearly ideal to set up my jig. I used a stack of large washers for the "mandrel". The only other fixture in the jig was an anchor where the eye rests. I'll link a simple sketch. Whatever you use for a jig, you need to be able to anchor it so that can resist your 100 or so pounds of bending force. Keep the anchor close to the mandrel to get a nice round shape in the bend. Mine started out a little flat close to the eye.

You might be able to get the spring to bending temperature with a propane torch but I found that the torch used with my bucket forge (see youtube) worked well to heat a six-inch or so section of spring. I'm no expert on heat treatment of steel and after heating and bending it probably should be tempered, but I've seen several accounts of home mechanics that have heated and bent springs with no ill effects.
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  #17  
Old 11-28-2016, 01:16 PM
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Default Re: What vintage fork will fit a 3-inch tire?

Wret the Simplex fork that Racie35 metioned is what I've used for my Harley Peashooter build. I added girders & elimination of the coil springs while changing to leaf should be easy. The 1957 Simplex fork measured 3 7/16" at tire height of 27.5" with plenty of height available for taller tires. The steer tube is 1".

Shouldn't be too hard to find one of these either. Rick C.
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  #18  
Old 11-28-2016, 01:51 PM
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Default Re: What vintage fork will fit a 3-inch tire?

Rick, are you and Racie35 referring to an actual motorcycle fork? My search came up dry.
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  #19  
Old 11-28-2016, 02:27 PM
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Default Re: What vintage fork will fit a 3-inch tire?

Wret this is a small motorcycle fork used on the Simplex Servi cycle built in New Orleans starting in the 1930's to late 1950's, check my Old guys Simplex (last few posted pages so you don't get lost in the Copper Gator info) thread to see the fork used in my Harley Peashooter build. I fit it (1957 fork) on one of Pat's Sportsman pedal bike frames. Rick C.
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  #20  
Old 11-29-2016, 07:49 AM
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Default Re: What vintage fork will fit a 3-inch tire?

Thanks for the information Rick. I took a look at Simplex forks. They do look great! I would feel bad cutting up a vintage fork as much as I would need to to make it look right and I fear there wouldn't be much of it left and the wheels are already turning on how to set up a fork assembly jig.

Curtis, I did find fork blades available pre-flattened. I do have access to a press but that takes a little of the guess work out it.
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