SYSTEM BLOODCLOD - Radio Controlled Monster Trucks (RCMTs)

The story continues...
The Beach frame was great because it was my first ever tube chassis. The truck was fun but I never really ran it a lot because HOOF was often my bashing truck. It was always in my mind though that while the clod often dominated the solid-axle racing class, that the jugg2/txt platform actually offered some good advantages for racing too. Namely, with the motors in the center tranny, the suspension of the truck could actually work better than the setup in the clod where a lot of the weight sits in the axles.

The problem though was that the motors and batteries sat so high in a jugg/txt design that it was just too top-heavy. The plan now is to design and build a chassis that keeps the weight as low as possible and also tune the suspension for handling. I want to build a low-slung MT that handles as close to a touring car as possible. :)

17.07.2004 The chassis - design and milling

I started out with concept sketches and then settled on a flip-transmission design which I first saw from Tamiya's own aftermarket TXT chassis. Then I decided to keep the battery as low as possible by trying to position in in front of the center transmission.

The concepts were translated into an AutoCAD design (first pic) where most of the measurements and geometry were worked out - putting this in software allowed me to really optimize the placement of all the components which was something I never had before. I also planned for less critical areas to be milled out for weight savings. In the suspension department, I designed the truck to use 3.5" shocks which I had but also to accomodate 4" shocks if necessary. Oh, the design actually allows for the transmission to be mounted in the normal configuration as well!

The design phase took a long time but I was pleased with the results. With some careful planning the chassis was milled out of 3.18mm (1/8") thick 6061 aluminum. The above pics show the chassis assembled with the center transmission. Third pic shows the suspension mounting options - the shock-link angle actually is kept close to identical when the mounting points are changed to adjust ride-height.

Next up... suspension links, suspension mounts, steering setup and possibly a skid-plate to protect the motors!

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19.07.2004 Suspension Links

Managed to complete the suspension links today. They are made from 8mm aluminum and threaded to fit 4mm setscrews. The ends are fitted with Kyosho 6.8 ballends and balls - these ballends are a little costly, but they are the most durable that I've used and should prove just as durable on this race rig.

Some of the parts I ordered have also arrived... things are shaping up well!

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20.07.2004 Suspension Links

Today I rebuilt the center gearbox and installed it into the chassis. I'll try different gearings but for starts I've installed 16 tooth pinions which are powered by 2 modified 14x2 motors. The fourth picture shows how close the battery sits to the center tranny - this keeps the weight low as well as close to the center line of the truck for stability and better cornering. I was able to optimize the positioning of the battery because the design was first put into AutoCAD.

These 2 pictures show the lower suspension mounts at the axles that I machined. They should hold the links sturdy while ensuring weight remains at a minumum.

22.07.2004 Upper Shock Mounts and Axle Mounting

Today I revised the design to include these adjustable upper shock mounts. With these I can adjust ride height by shifting the mounts up or down and I can also easily accomodate 3.5 or 4" shocks simply by flipping the shock mount. With options to mount the extention inside or outside the chassis plate I can also adjust how far to "lean" the shock toward's the truck's centerline.

So far building this chassis has gone smoothly, but along the way experimentation is quite interesting. These pictures show the axles mounted as well as the configuration I settled on for now...

What's next? Click here to find out!