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URC Projects: Ultimate Bit Char-G

Enter the world of the Tomy Bit Char-G, JANG style. It is a world where speeds are high, turns are sharp and Dremels patrol ominously, seeking out and destroying unneeded micrograms.

Phase II:

Phase I was unveiled in early September '02 as chassis mods for Phase II had already begun. Two months later, the project was complete in final form. The original had improved the car's handling by such a large margin that I immediately wanted more raw power and speed to keep things from getting boring. Much of the ultra-micro community was getting interested in high-voltage possibilities around this time and some adventurous owners were cutting out their rear windows to mount a second cell on top of the motor mount. A few went so far as to reverse-engineer and upgrade their circuit boards to handle three cells. The resulting beasts where wheelie-monsters and spawned a generation of "Bit Dra-G" racers, but turning at speed was not at all recommended, due to the excessively high center of gravity. My Phase I Dremelling experiments yielded a spark of inspiration to do things a bit differently. Take a look at this Phase I side view. See all of that space in front of the battery? Can you guess where I'm going with this? The only real question is why nobody else had tried this before.

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Fitting a 2nd cell onto the floor of a stock-length Bit Char-G ended up being quite a test of Dremelling skill. Both the front and rear of the chassis tub had to be trimmed back significantly. I started out by disconnecting all of the electronics and spending a couple of days planning my cuts. A lot was at stake, including the stock battery tabs (which I wanted to leave intact), the all-important forward/lower motor clip, and the post to which the front upper chassis plate is held down. By the time I was done, I was seriously worried about chassis flex. A tiny fraction of a milimeter of deflection could make the difference between "nailed" handling and catastrophic loss of traction in every turn. Instead of adding the weight and complexity of a chassis brace, however, I trimmed the new extremes of the battery compartment just barely enough for my purposes, allowing the two cells to squeeze in with a very snug fit and become structural members. With these big ole' things accounting for a good 80% of the vehicle's weight, I was happy to get them to better earn their keep!

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Well whaddya know, it all fit! A dab of Shoe Goo was used to firmly (but reversibly) reattach the circuit board upside-down for clearance. The ghetto-looking balsa blob on the right side with the two bits of wire sticking out of it is the new charging jack, which perfectly accepts a standard receiver pack connector mated to a Radio Shack AA holder. I only used two cells to charge with, but later learned that I should have used three for a stronger charge (something about relative electrical potential -- it's a voltage thing).

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To help with radio signal clarity, I discarded the old braided receiver antenna and replaced it with a solid copper wire of equal length. On the transmitter end, the springy, wailing retractable wire had to go as well, but instead of removing it, I just moved the jumper wire over to a freshly-mounted telescoping stalk from a decomissioned Traxxas radio system.

With the Shoe Goo set up, the car fits together as neat, tight package. Only re-mounting a couple of the individual components on the circuit board would have produced a result I'd be happier with.

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To finish everything off, I decided to go with a more sleek, hip-hugging body, stealing a McLaren F1 shell from a clone made by Shen Wei Qi (I think that was the name of the company), lowering it as far as I could and then finally throwing some URC-themed paint on it. I'll have to admit, I have no talent for painting 1/64th scale bodies with with a brush, but at least it's recognizable.

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Extensive testing with setup options eventually yielded a configuration of Tomy option purple front tires, Trueno set soft black rears, and Tomy's highest gear Bit Char-G gear ratio. Oh, and of course there's an Ultimate Bit Char-G motor in there (a very high-torque unit with an OEM rating of 32,000 RPM).

Hopefully at some point in the future I'll find the time to edit together some videos to show just what this little screamer can do.

Phase I:

You've seen where the project ended up, now go back in time and see where it all began. Phase I is archived here.