Long ago I bought an OFNA DM1 pro, but I never liked its factory settings. So from the first day I set to work to turn it into an electric car. Following I tell you what I done to make the conversion.
Of course, the first thing was to remove everything that was related to the gasoline engine: engine, fuel tank, motor mount, silencer, mainly. Once the space was clear I began to think about how to install it an electric motor, batteries, ESC. I opted for a similar solution to that of his younger brother, already electric: the OFNA DM1e, ie, a double battery holder and the ESC on the left side of the car, and the engine and mounting on the right side. With this basic outline I found the first inconsistency: the installation of the servos and receiver so is that I had no choice but to look elsewhere for them. Well, I'll think about it ...
From the OFNA DM1e I learned that the weight distribution I is not optimized: the centre of gravity is shifted to the left, and pretty. Depending on the batteries you use and the weight of the motor, you may end up having to counteract the offset up to 200g on the right side. So I thought: 200 grams give or take are the weight of a battery. If I put a third battery on the right hand side I can feed the engine with 6S instead of 4S... The issue was now search space on the right side to add a battery and motor. The motor has a fixed place on the right side, which is behind the spurs gears, so that in the normal direction of rotation causes the car forward: then the battery should go ahead of spurs. Well thought was not bad solution: the third battery would advance the longitudinal centre of gravity. The motor is clearly behind the centre of gravity, while the left side batteries get more or less in the middle. Of course I did not find in the parts market a support adapted to the space I had, is that I've had to make my own tray, which ultimately I designed so that the battery is installed sideways.
Next was to fix one thing I never liked about the configuration of the DM models: the suspension. DM1e front shocks are horizontal, Formula 1 type, while the rear is the traditional vertical configuration. EL DM1 pro carries front and rear horizontal!. At the time, for DM1e, I already made a vertical tower for the front suspension and found that gripped and turned the car much better. Direct and without thinking twice I made a copy of the tower and bought another to put on the rear suspension. This also helped me to clear the middle of the car and, for purists, lowering the centre of gravity.
Now I had solved the motor installation, ESC, batteries, and suspension, I come back with the installation of the receiver and servos. Yes, I write it in plural servos, because from the first moment I decided I was going to keep the two gears. If you have two gears on an electric car you lose the motor braking capability, then you need disc brakes and a servo to act them. This is weight, the bad, but it is also possible to optimize gear ratios for low and high speed, in addition to reducing the motor amperage. What can we do!, You cannot have everything!.
Once again I went to my experience with DM1e. Already considering that car, I realized that the gear box and centre spur mounts were the same height. This allowed me to put an upper sub-chassis style electric touring cars. And so I did. With a piece of carbon fiber around two millimetres I joined the front gear box, the centre spur mount the rear gear box. There is a slight increase in weight compared to the standard solution in the form of off-road 1/8 braces, but this provides structural rigidity, plus load spread to other car parts in case of frontal impact. So, I adopted this solution for conversion.
The concept worth, but the piece could not be copied, because, the distance between gear boxes is different. Also I still had to find room for the servos and radio receiver. After a session of "brain storm" with a servo in hand, a piece of carbon fiber used as sub-chassis and the car, I found the position for each of the parties: the servo steering, in the front and inverted, through sub-chassis; the servo brake close to the disks, also through sub-chassis and finally the receiver directly secured with double side tape on the sub-chassis.
The motor. The motor also had to be modifed, namely the rotor shaft. Usually the shafts are not very long, 20 to 30 mm. But I needed more than 35 mm in order to put two gears. So I got in touch with Neumotors, brand of the motor to be installed, and I asked them to manufacture a rotor with a longer shaft. I asked for a diameter of 5 mm to directly use the common gears in the category, but it could not be and they made with a diameter of 8 mm. At first I thought, no problem I lathe it to 5 mm, and that's it, problem solved. Ha! As I had the rotor and began to lathe it, the problems started. The shaft is so hardened that cutting tools run away from it! Then, if I could not lathe the shaft to 5 mm, I should lathe the gears to 8 mm. Luckily OFNA pinions have a thicker neck than usual. I bought a few and lathe to 8 mm diameter, with some difficulty, since they are also hardened.
To end the conversion I did, with a low density foam, a rear bumper that is supported in the diffuser.
Here you have some photos of the car and the parts made.
Overall Top view of the changes.
Car with batteries installed.
Support batteries and ESC. From the DM1e piece.
Front battery tray.
Motor and support. The engine is a Neumotor and support comes from DM1e.
Front suspension tower. Carbon fiber.
Rear suspension. DM1e heritage.
Central mount. Gears. Brakes.
Upper sub-chassis. Carbon fiber.
Servos and receiver.
Rear foam bumper.
DM1e and DM1 pro comparison
In this picture you can see the two OFNA DM1 Rally Game with their bodies.
Finally some pictures of the car the first day it was released.
Ah! I forgot. A car like this deserves a good "garage", and this is what came out my imagination factory.