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Simplifying the fork with the R-Geo Victory


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#1 JimF

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Posted 31 July 2013 - 01:47 AM

Since I've started exploring the tuning fork idea, I've built maybe a dozen or so frames using the concept. Lately, I have started to wonder whether the hinged rail concept needs to be in the tuning fork configuration as we currently know it or whether it could be simplified. Here is the latest using the R-Geo Victory chassis plate. This build was so simple and easy that it seemed like cheating.

 

I have eventually targeted this frame as a flat track car but the initial build is closer to a speedway car in weight. Here is the starting point. The chassis plate is .050 brass and includes a 6 gr. center plate (shown here) which I cut out for starters. I chose an R-Geo 3/4" bracket in .040 brass.

 

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Here are the dimensions that we have to work with. Shown here are a few shaded areas that'll be cut out and also the main frame rails. These rails are .062 wire in tubes both fore and aft. The front tubes will be free hinged providing the effect of a fork but in a straight rail car. The rear tubes will not be free hinged. They will be soldered solid. The rear tubes are here to provide the same spacing and elevation as the front part of the rail.

 

The spacing at the rear with both rails sleeved provides an exact fit for a 3/4" bracket. There is a small hole in the rear tubes to allow solder to penetrate better.

 

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Here is the nosepiece with a little detail to add. The tabs that hold the front axle are a little delicate. These are two little bits of .075 wire ready to be soldered in place as gussets for the uprights. 

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OK....ready for the Jig. Here is a step to put into your routine, Use your micro square to form a front edge square for the bracket. Making sure that the flat edge of the bracket is 90* to the main frame is an overall key. Also, you can see here that the bracket w/bearings is centered and held in place with a variety of set screw keepers and some old gears. This is where you'll also check that your bracket is providing the proper clearance when sitting flat on the block.

 

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Here is the chassis plate with the front gussets in place, one frame rail assembly in place and tacked and the next one ready to go in.

 

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Good view here of the front gussets, the main rail assemblies in place and the rear control hinges. The chassis plate will be cut clean through at the line shown. The rear control hinges are shown before assembly. The front bit of 1/16" sq. tubing will be soldered solid to the plate just forward of the cut and overlapping it a little. The second bit of tubing will be soldered on the rear part of the plate next to the bracket. The rear (smaller) tubing bit will not be soldered to the plate at all. The hinge rod is .032 wire. It will be soldered solid inside the front tube but free to rotate within the second. The small bit of tubing will be soldered to the hinge rod as a "cap" or rear stop. The goal here is to set this rear control hinge up with zero gaps between the 3 bits of tubing.

 

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Here is rear control hinge set up and finished as described. Aside from hanging the front axle and setting up body pins.....we're done.

 

How easy was that???

 

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Finished product shown with another "tuning fork" chassis. The upper frame is all hand cut from .062 brass and is more in the realm of what we've come to know as the "tuning fork" design. The Victory is still hinged on the main rails but the rails are straight and the build is much easier.  Both of these cars weigh in at about 96 gr all up with body. Both cars use the same dimensions and rail sizes.

 

Both of these cars exhibit to very free twist flex of the tuning fork concept but the flex is notably firmer on the Victory car.

 

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Later, we'll seeeeeeehowtheyrun


  • Tim Neja, miko and Jim Lange like this
Jim Fowler




#2 Pablo

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Posted 31 July 2013 - 04:50 AM

Sweeeet !!! Thanks for sharing that, Jim !!!
Paul Wolcott

#3 spudboy

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Posted 31 July 2013 - 06:56 AM

What Pablo said Jim!


Nate "spudboy" Bemis

#4 SlotStox#53

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Posted 31 July 2013 - 06:58 AM

Awesome and so simple !! Thanks for showing such a neat and simple design, it brilliant! What a cool translation of the fork into straight rail ...

Will have to put one of these together ..

Paul

#5 Tim Neja

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Posted 31 July 2013 - 11:27 AM

Always great to see your builds--and love your thoughts and documentation!! SWEET!! :)


She's real fine, my 409!!!

#6 TG Racing

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Posted 22 July 2014 - 01:41 PM

Jim,   Just getting ready to do this build.  Do you have any changes or insight since you built this last year?  Thanks for all the great articles!!


Thom Greene

#7 drrufo

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Posted 22 July 2014 - 02:23 PM

Jim, are the gussets needed on the front bracket? If they are needed would a tube be just as good in support but lighter in weight?


John Andersen
DR Racing Products


#8 JimF

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Posted 22 July 2014 - 05:09 PM

Jim,   Just getting ready to do this build.  Do you have any changes or insight since you built this last year?  Thanks for all the great articles!!

 

No changes as far as performance, it worked well everywhere I tried it. It does seem that the one piece brass front can hold a bend if you really thump it hard. Eventually, I made a simple cut right at the beginning of the pan to separate the pans from the rear part. Then I tied it back together with a "U" shaped wire like a fixed hinge. It didn't change anything in the way the chassis worked. I'd take a new pic but I sold the car some months back.

 

Jim, are the gussets needed on the front bracket? If they are needed would a tube be just as good in support but lighter in weight?

 

Honestly, in retrospect.....they probably don't need to be there. If I built this again, I wouldn't bother. If you did do it, a tube would be fine.


Jim Fowler





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