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This is a short description on my built of my Kyosho/COX Tomahawk that I later named Tomahawk R for the US VONats 2013.

This journey started in early January after me and my wife decided to visit New York in September this year. I contacted Erich Reichert to get a hint to witch weekend the 2013 VONats will be held and so he did. You need to do some planning when you gone travel almost 4000 miles for a race.

I had this idea for some time to try to build a new runner out of a Tomahawk. So I contacted my friend Dwayne in California to exchange some ideas I had to improve the performance of the Tomahawk. Dwayne also had some new ideas he shared with me for this build! Dwayne use to race with a Scorpion in the early 80’ and mix it with the big boys.

My starting point was that all my alterations and hop-ups on the Tomahawk should already have been done/existed in the early 80’. No fancy modern parts ore knowhow from twenties century. This excludes battery, ESC, radio, tires and wheels.

After a “couple” of mails back and forth, Dwayne made me the parts I required to start building my new runner.
In the meantime I was trying to figure out what shocks I would use that was good enough. A friend suggested Kyosho gold-shocks, but those were out of the question. They were first realest in -87 and for that disqualified. Instead I was locking for the Lad Jump shocks (CB-88) for the rear and Kyosho’s #1886 for the front. Then I discover that I had a set of other shocks that was something in between this two in length.
I decided to us these slightly longer shocks for the front. Later I found out that these socks came from a Kyosho Fantom 20, a 1:8 on-road gas car. The part number is FM-71
All of the shocks was rather shady and needed to be re anodized red and at that time I also decided to anodize all of chassis parts from Dwayne black.
These old shocks don’t have any pressure disks and that’s a problem when the shock is fully compressed. So I used 4-5mm shorter shafts when I rebuilt them, to prevent the shock piston to work in too much air.

Over to the gearbox: I decided to go for a Thorp/Dirt Burners diff even if it much heavier than the Tomahawk’s gear-diff (more mass to set in rotation). I also made a dust shield with the help of the Swedish king’s head…
Dwayne’s parts arrived in the end of April and were immediately sent away for anodizing.

Most of my inspiration for this built came from Japan, those guys did some pretty nice developments’ on their Scorpions/Tomahawks and SRB’s in the early 80’. There were a lot of mix brand cars and homemade parts. In US the cars was more or less stock, and not that many hop-ups. For instance, a Thorp diff’s price tag was $75, and that was a lot of money 30 years ago, and still is.
In less than two weeks my parts returned from anodizing nice black and red.
I quickly assembled the cassis to see how it looked… and I like what I saw…
I made glass fiber cassis plate out of a 1.5mm black sheet with outlines from the Tomahawk body. With this in place I can mount the battery and servo much lower than original.

I wanted to widen the 200mm front more than those 14mm you can do with the CRP 1707 axle. So I made one that was 25mm wider than the CRP axle out of 5mm silver steel. The two first pictures are from when I made the prototype. This is a tricky alteration, will it bend if I rollover too heavily on the track… And the answer to that is YES it will bend as it did during VONats due to the small original bumper. I don’t think that would have happened if I had used the much wider and much more shock absorbing Pro-Line bumper. Lessonlearned…
On the last picture you can see that I have moved out the shock towers 10mm on each side with custom made spacers that Dwayne made for me. I have also used MRP’s plastic front arms and I made wider copy of Dirt Burners front sway bar.
I also made the rear end wider from its original 230 to 250mm. So Dwayne made a custom made suspension mount plate widen 10mm on each side. He also made the trailing arm pivot’s in one piece.
When I was mouthing the rear trailing I was using Hpi’s suspension shafts that have the exact same measurements as the original ones 3 x 43mm, but the quality I much better. Hpi’s 3 x 44 will work as well, maybe even better.
At this time I hadn’t decided if I will go with the original trailing arms or those plastic from MRP. Later on I did decide to go with the MRP ones sins I had MRP at the front and that they prolong the car a cupule of mm to.
Now it starts to look like a car.
I also made a sway bar for the rear copying the one Dirt Burners mad for the Tomahawk/Scorpion

Back to the front end. To minimize the bump steer I moved the steering rods back and out, and it worked grate.
[youtube]kYls0scmTVw[/youtube]


In this picture you can see that I chose a short-pack and I made the location adjustable.
For wheels I have chosen RB5 rear wheels from Borrego and the front are Durango Dex210wheel also from Borrego. To get this front wheels to fit the Tomahawk Dwayne made me new prolonged front wheel axels.
Now to the body; I wanted to lower it as much as possible. This made the roller bar to be removed, and the body to be cut in two pieces just behind the cab! This why, I lowered the body about 15mm compared to the original possession. I also fitted a wing using yet another of Dirt Burners hop-ups; actually I used the aluminum pips from an Ultima 2 wing-mount. But the solution is the same. Time to do some painting…

This is how the pint did turn out in the end. And yes, you need a painted driver and headlights if you are competing in the Classic class.
[youtube]py9OVJdte-c[/youtube]

How did the Tomahawk R perform in the end? Well… it turned out real nice, but I never got the time to sort it out. I had two 2x5 minutes on my home track (Astroturf) to see if everything work as I hoped for. I would need another day extra on the Bethel race arena to dial it in, in a better way. The biggest problem was the lack of rear grip and no slipper to adjust it with. So no more than half throttle down the straightaway… The driver’s lack of driving hours, it has been 16 years sins his last race, after that maybe 2 hours of driving. But I don’t regret traveling 4000 miles for this event; I had a blast racing this “old” car and end up 7:th in Classic class. A special thanks to my old racing buddy Bo that pick me and Joel up at the airport in NY and opened his home for us. And there already talk among the Swedish vintage guys who will make the trip next year to VONats 2014. For my selves… well, I haven’t decided anything yet…
If you want a more detailed version and more pictures you have to use Google translator and visit this Swedish thread.
http://rsb.se/arena/showthread.php?80645-Kyosho-Tomahawk-till-US-VONats

I almost forgot: The car got the “Best in Show” award…

Lars, that was a inspirational build!! The award comes as no surprise!

SO great you managed to get the car from bench to trackside!

Congratulations!

Wohooo! The somewhat secret build has finally found it's place also on rc10talk. You definitely know how to write inspiring threads.

I had the opportunity to travel with Lars to the VONats event and we got about five days of racing and discussing rc cars. It was a great trip!

Fantastic build Lars.

Very nice! I am a big fan of the era-correct build, and this one is amazing!

Finally!
Fantastic build Lars, really inspirational.

That's some excellent re-engineering and resto-modding, Lars...that's the kind of stuff I love to see.

That one picture of your red shocks before the stripping & reanodizing confirms how damaging those set-screw shock-collars can be to the aluminum shock bodies. I will never use that kind of spring adjusters on any of my cars. I'm glad to see you went with the stock style of collars using screws to close the ring instead of set-screws pipping into the shock bodies.

Love the action shot of the Tomahawk, and congrats on the #1 prize!

Thanks guys for all the nice comments!

There one thing that I forgot bring up from this project that I know is a problem for Tomahawk/Scorpion runners (at least for me), and that’s gearing. If you are bit familiar with this cars you know there is two gear ratios, 6.7:1 and 10.72:1 Running hand-out motors as I did at VONats this problem had to be solved.
CRP made adjustable motor plates (#1708) and are easy to reproduce. The problem has been to find pinions in module 1 that fit 3.2mm motor axle, just for 5mm axels. Then I found adapters that taking care of that problem.
The Tamiya Sports tuned motor (VONats hand-outs) should be geared 9.2:1 for off-road. And after some research and test I got as low as 8.25:1 without overheating the motor.

Beautiful job! Always wanted to build a similar racer from the Scorpion/Tomohawk chassis. Curious however, how much rear toe does the car have (per side) -Jeff

Excellent build and result Lars. Thanks for sharing this.

Hi Lars,
In Denmark we had 3 different gearings, I don´t know if that last gearing was provided by Graupner or the entire bag content was Kyosho. I don´t recall seeing three gears in a bag with Kyosho header.