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New "center spine" F1 build

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#1 JimF


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Posted 08 August 2014 - 08:21 PM

Center Spine?.......................Yep, the infamous center hinge all soldered up solid so it's nice and legal.

But why? you axe..................or.......mebbeso yer not axin'..........but here's why anyway.......................


  • When I built that experimental CA+ car, I was underwhelmed with the effect of the center spine/hinge.
  • But.........I converted the car to a regular Can Am and messed with it a bit and I became more interested.
  • Interested enough that I've built a total of three Can Ams and a stock car with the concept.
  • After preliminary testing, I'd say that those all work better than I expected for light, shortish cars.

Hence......this here flatrackish F-1 with a center spine and another idea that's been percolating.

  • 1" nosepiece and bracket are R-Geo .050 (both are substantially hacked up)
  • Main frame rails are 3 X .047- far fewer rails than normal for me.
  • Motor box is .055 wire and is fully separate from the frame rails.
  • Center spine is .062 with the "seat block" of .062 brass.
  • Weight will be focused inboard rather than outboard, hence wide bracket and narrow pans.





Front detail:

  • Horizontal tube of 3/32 tubing are for the front pan hanger.
  • Little bitty longitudinal tubes of 3/32 are for the center weight hanger/stops.
  • Aft front axle uprights are doubled up and angled outwards to 2" (not legal for IRRA)




Rear detail

  • Extra bit of .055 wire laid in to strengthen the joint between bracket and main rails (this is one of my SOPs)
  • Bracket brace/rear weight is .062 brass.
  • This is a good look at the motor box/spine hanger and how it is separate from the frame rails.
  • Rear weight blocks of 1/8" X 1/16" brass will also support the rear pan stops.




Pans and weights:


  • The pans are shown outboard and are 1/8W X 1/16"thick.
  • Center weights are 1/16" brass and go 6.8 gr ea.




95% done:


  • Pans in place and hanging off of a .039" front hanger.
  • Center spreader is .025" wire (blue) which also hangs the rear of the center weights.
  • Front limiters (red) are .047 wire in the small bits of 3/32" box tube.
  • Center weights will flex pretty freely on the .025 wire at rear, but the front limiters will control them.
  • Rear limiters (purple arrow) are .047 wire going into bits of 3/32" tubing soldered onto the rear weight blocks.






  • Still need bearings and body mounts but this is ready for cleanup.
  • This will go about 105 gr with body as shown with the center weights.
  • If I wanted to drop out the center weights for a speedway track.....she'd be about 91 gr w/body.

  • endbelldrive and miko like this
Jim Fowler

#2 Tim Neja

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Posted 09 August 2014 - 12:21 AM

Looks REALLY good Jim!! Love to hear how it works on the flat track!! I've been wanting to do a center spline car since the Kamo stuff works so well on the King!!

She's real fine, my 409!!!

#3 Dominator


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Posted 09 August 2014 - 06:23 PM

One of the coolest F-1 builds I've seen!

A motor is only as fast as the chassis it's in.
Dominic Luongo

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#4 John Gorski

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Posted 09 August 2014 - 07:03 PM

Sano Jimmy keep up the creativity. :good:  

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#5 JimF


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Posted 10 August 2014 - 02:42 AM

Thanks guys.


I'm not real sure where the center spine idea is going but the build for this frame started from a good spot. By that I mean that I have a herd of F-1s that are already good for our next race venue so I could afford to mess around and do this one as a design exercise. This started with the idea that came from the "spinal" Can Ams. The idea was/is that the spine may allow me to run a car with fewer main rails and thus more flex than I could normally get away with. So far.....in limited testing, that seems to be true with the Can Ams. If it works out, I'll have more bite and thus a faster corner speed without having a car that's hyper critical to drive. So far the spinal Can Ams seem to have that character. Aside from the spine, I've had the vague idea for some time now that concentrating the weight closer to the center rather than on the perimeters, is a good thing. If this F-1 works out, it'll be a great car to put in the box next to several multi-railers, a Samson clone, and an R-Geo (ish) tuning fork F-1.


Cuz..............more is always better

Jim Fowler

#6 Dave Fiedler

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Posted 10 August 2014 - 01:37 PM



  Great work, you are truly a Master builder. Love looking at your frames!


Sano Dave

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Dave Fiedler
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#7 redbackspyder


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Posted 10 August 2014 - 04:12 PM

Jim, you ought to take a look at the F1 that Dennis built for himself and Herman James, they are tuning fork f1's with kind of the same Idea, and they both seem to work really well... Very forgiving and great on our flat track, just a thought

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#8 JimF


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Posted 10 August 2014 - 04:21 PM



Thanks, I already have one of those. That design is actually a spinoff of the R-Geo fork/brass rail that I wrote up about 6 months ago. And yes, it does work really well. It happens that recently, my multi railers have been better but just by a little.

Jim Fowler

#9 A. J. Hoyt

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Posted 11 August 2014 - 02:44 PM



I love the "old west saloon doors" center weights!


I could see hanging the aft ends of those weights with square tube soldered to the aft ends of the weights hanging from the wire that goes left pan to right pan - kind of a modern "clicker" version as used by Joel Montague way back when - for more pan shift / movement (a bit more independent from the left and right pans).


Very clean design and efficient use of materials to minimize mass. Everything has a purpose! Nice!



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#10 JimF


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Posted 11 August 2014 - 05:16 PM

Hi AJ:


You are right of course, the center weights could be loosened up via the crosspiece/spreader going free through a tubing bit at the rear of each plate. The surrounding frame rails would provide limits and the plates would not be in danger of moving too far or riding up onto the rails and binding up. FWIW.....I tend to think that chassis components that represent significant weight, prefer a little movement but without the ability of the center weights to slap around against the other frame components.


This is however, a personal opinion/preference and your idea would be very good. FWIW......s'more.......it seems to me that F-1 frames have gotten pretty complex with multi directional movement etc. That stuff may all be very good but I'm not sure it's truly necessary. I think a little movement, properly controlled is all you need and tends to make a little cleaner/less complex build.


Then again.................I've been wrong before (often).

Jim Fowler

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