What is wrong with MTX4R ..... is primarily the transmission.
Other changes are:
- Axis of transmission and gearbox, differentials and pulleys of xray
- Move the batteries from the exhaust side
- Low friction bearings: plastic parts need to work so that the rotating parts .. are not too heavy braking. So file, reamer and sandpaper in hand.
- Belt high sliding lubricated with silicone spray (including pulleys)
Also need to reduce the weight of the box ... too heavy:
- Screws lighter: about -25 g
- Uniball lightweight: about - 16 gr
- Li-fe batteries: approx - 30 gr
- Lightweight brake discs around - 10 gr
- Engine mounts lightweight: about - 5 gr
- Xray transmission using many grams are recovered. Finally we come to have a car that weighs less than 1700 gr.

It has been proven to shorten the "step" on the rear ... but do not go
A little better if the operation is done on the front axle, but it is laborious.

The balance is not optimal. The MTX4R is very heavy on the side of the servi

With these changes the car is much better but not enough. We want MTX5.