Here´s the final chassis revision im doing for this car. This has everything that i can think of:
- Support for aluminum body posts in front and back.
- Support for RB5 rear chassis plate and suspension holders.
- Support for RB5 rear bulkhead.
- Support for original Ultima ST rear bulkhead.
- Support for 3S batteries, the max dimensions have been designed for this battery: (i use this:
https://hobbyfactory.fi/p65118/team-orion-3s-55c-ranger-lipo-battery-11-1v-4300mah-t-plug-ori14326). Those are the absolute max physical dimensions for battery.
- Support for aluminum battery holder posts (bolted through the chassis).
- Slit for steering servo cable (cable management)
- Additional 2 screw points in front chassis (i honestly dont know what are those, but i saw them in RB5 chassis pictures, so added those (the screw locations ARE NOT THE SAME THAN RB5 CHASSIS AS I DONT HAVE THAT CHASSIS).
This chassis will be durable enough for even a hard driving and jumps if aluminum body posts are used. The chassis needs to be printed from Carbon Fiber PETG, or CF Nylon. I personally like to use CF/PETG as its easier to print and also doesnt flex too much. I have tested this chassis with my own car in Finnish winter. The lowest testing temp was -28C and included full speed crashes to snowy/icy things. I broke some of my other 3D printed parts and also original Kyosho parts, but the chassis holds on. So its good to go.
If you are using this chassis and slightly shorter than max length battery, you can use slicer and slice the chassis half from the straight area around the battery area and make it longer or shorter. Do the same for the battery holder, print the chassis and voila, you have a custom length chassis. If im correct, this car suffered from too long chassis, so ideally you would have to shorten it up.
I have tested it with hard gripping rear tires and indeed, even on the snow the car starts to understeer with OEM length chassis.