28ga

I've just completed a custom 2wd truck project. I built a chassis from some FR4 fiberglass circuit board material, and a front clip with some misc. A-arms and a block of CPVC to mount the A-arms. The transmission I used is a Tamiya Super Sabre rear end, however to push the weight back as far as I could I mounted the transmission backward. I am currently using a zero degree timing motor, so it runs ok, but I would like to get more speed. Are there any motors available that have a negitive timing or do I have to buy a mod motor with adjustable timing? What other options are there?

I will appreciate any help you can give me?

MinotRich

Tower Hobbies sells Magnetic Mayhem motors that run in reverse. Aircraft flyers sometimes use them to turn a gearbox for flying but they were actually developed for car/truck use.

28ga

Thanks for the info on the Magnetic Mayhem motors. I have a follow up question, would running on 7 cells give me the same result as running a better reverse direction motor? Does anyone know if the LRP Runner or the Taxxas XL-1 can handle 7 cells?

drf

Most modified motors I have seen (rebuildable) have both advance and retard timing. Any of them should do the trick. Instead of timing them in advance (which is the normal) since you motor is mounted the other way round you just retard them at the same amount.
If you run 7 cells you will get more speed compared to the same motor with 6 cells.
If you have a stock motor with 7 cells and a modified 11x2 with 6 cells the modified will be faster. It depends on the motors.

kn7671

All you need is a normal modified motor with adjustable timing. What you do next is very easy. Release you springs on the brushes, or pull your brushes out of the end-bell to where they no longer contact the rotor com. Take out the 2 screws in the endbell that hold the end bell to the motor can. Now ROTATE your end bell 180 degrees, then reassemble the motor. This will reverse the direction the motor spins when current is applied. You won't have to resolder anything, or buy any special parts to do this.

Note of caution: I would not reverse the direction of an older modifed motor without replacing the bearings first. I have seen motor bearings fail when they turn the opposite direction when it was never run that way while being broken in, etc... This may be one of the main reasons why race type ESC's don't have reverse, besides making for safer racing conditions. If you are buying a new motor, then totally disregard this paragraph.

drf

Rotating the end bell by 180 degrees should not make the motor rotate the opposite. The only thing that changes is the timing (exactly -+ change). The olny way to make it rotate the opposite way is to reverse the voltage

someguy

My Feedback: (1)

That is not correct. Rotating the endbell 180 degrees is exactly the same as reversing the wires. Just think about it, when you swap the wires you change which brush is negative and positive reletive to the magnets. One magnet is north and the other is south. The same thing can be done by rotating the endbell 180 degrees and it only requires loosening two screws, no soldering. BTW if you do reverse the rotation be sure to retard the timing as stated earlier, if you had +24 degrees of timing then make it -24 degree etc.

SpoonAvenger

Rotating the endbell 180 degrees will in fact make it rotate the opposite way.

28ga

While rotating the end bell 180 degrees does make the motor turn backwards, it is the same as swapping the positive and negative leads. The issue of timing still remains. No matter which way the leads or end bell are oriented, the timing on a conventional motor still favors the conventional (forward) direction. Given this I will need a motor with adjustable timing and set the timing negative or get a motor with a fixed negative timing designed to run backwards.

Thanks for everyone's input. I think I am going to try the Magnetic Mayhem motor designed for reverse direction unless I can find a used mod motor with adjustable timing for cheap.

kn7671

Reversing the Positive + and Negative - wires does the exact same thing as rotating the endbell. The reason I said to rotate the end-bell, is because you still wire up everything on the motor exactly the same, then rotate it to reverse it. As for timing, I have not ever seen a modified motor than cannot be timed just as much in both directions, it just so happens that some of the labels on the cans only mark positive timing, so you would have to measure the negative timing when reversing the motor direction.

kn7671

DRF: When you get the chance, try rotating your end-bell...