Mitch Richling: Mini-T Modifications, Brushless, Li-ion
| Author: | Mitch Richling |
| Updated: | 2021-05-23 |
Table of Contents
1. Introduction
The Mini-T Team Losi is a tiny, 1/18 scale truck. When I got mine, it was the hottest car in the shop! They still are very popular and new stuff is coming out for them every day. Several version of the truck are on the market today, and some of them are as fast out of the box as you can reasonably expect to drive. This page is about what my wife and I did to our original Mini-T trucks to make them a bit more fun.
2. Modifications
My Mini-T is the most extreme of our trucks. After I got done with it, the thing would run at about 40MPH and do rings around my E-Maxx! It has absolutely none of the electronics that it came with!
2.1. Motor
The stock motor has been replaced with an airtronix brushless motor. This motor is designed for airplanes, and has significantly more torque and speed than the motor it replaces and doesn't perform well in reverse. The stock transmission is just barely strong enough for this motor. The brushless motor produces so much torque and speed that the rubber tires expand to the point that they can pop off the rims, so I glued the edges of the tires to the rims.
2.2. Gear Cover
The gear cover won't fit over the motor pinion gear, so the transmission plate has been violently drilled out to make room for it. The gear case cover no longer can fit on the car as the motor pinion, an 22 tooth aluminum replacement for this particular motor, is in the way.
2.3. Receiver/ESC Box
The Receiver/ESC box has been replaced with a brushless motor controller and a Futaba, 3 channel PCM 1024 unit. The ESC is designed for airplanes, so it has no reverse. This requires some programming trickery, but the 3PK radio I have is flexible enough to manage nicely. For the steering servo (in blue), I filed the shaft of a HiTec servo into a hexagonal shape and used the stock coupling. This has held up amazingly well. I had to add some plastic fill into the servo housing to keep the servo steady.
2.4. Transmission Heat Plate
The transmission heat plate needed to be modified to fit the new motor.
2.5. Battery
The power source is an 11.1 volt Li-ion battery pack with a modified battery connector – larger than necessary but I use the batteries in higher current applications as well.
2.6. Battery Tray
The battery tray's retaining bars at the sides of the body had to be cut away to hold the new battery and electronics.
3. Result
The result of all of this is a little car that will do at least 40MPH in a straight away. It is also a little car that will be airborne if it hits, at top speed, even a small swell in the concrete. I have seen this car do a 15 foot jump after hitting a wavy bit of concrete in my parking lot at home! This car is VERY hard to drive with this kind of power. I have three programed modes in my radio for this little car:
- A 1/10 max throttle only so other people can safely drive the car. In this mode my mother in law can drive the car and so can the neighborhood kids that live around my home.
- A slow ramp up on the bottom end of the throttle giving a much slower, and more controlled, take off. In this mode my wife can drive the car without hitting anything or flipping it over.
- A linear ramp to full throttle that I use to drive with most of the time. I still end up walking out and flipping the car over quite often, and occasionally bumping into something because of a lack of breaking power. It's great fun.
4. Notes & Updates
- The steering servo will break at some point because of the forces put on the modified servo shaft. At the time I had no real choice. I attempted to use the stock servo shaft by placing it inside of a HiTec servo case; however, this won't work as the gears are different. Today we have the option of simply buying the HiTec servo saver kit from Team Losi, and that is the best way to go.
- The ESC is for airplanes, and has no reverse. This is obviously not ideal for a car. Today you can buy small ESCs designed for cars that can drive brushless motors – get one. Better options exist today from Castle Creations and others.
- The only real choice for the new motor was a small brushless job for airplanes, but today you can bet a better motor from Team Losi and other sources.
- The ESC I'm using doesn't understand Li-ion batteries, and thus I need to be careful not to run the battery down all the way or leave the battery hooked up to the ESC – running a Li-ion pack below it's minimum will ruin the pack! Better options exist today from Castle Creations and others.
- If you just want your car to go twice as fast, then just run it off of a 7.4V Li-ion battery pack. For most people, this is more than fast enough for such a little car.