Dual Motor Problems

[RCbasher]

For the last two months I have been happily running my berg. I have it set up with two Holmes Hobby 35 turn motors, a tekin FXR esc, a CC bec, and a max amps 3 cell 2200 lipo. I have the motor wires routed from the esc to the rear motor, and then from the rear motor to the front motor.

The last few times I have run the truck, I have noticed that sometimes the rear rear motor will be locked when the front motor is running (almost as if I have a DIG set up although I do not). Today the problem got worse and I took the truck apart to trouble shoot and hopefully diagnose the problem.

First, I took the wheels and I gear cover cases off both the motors so I could easily observe the pinion gears. The problem became more clear at this point. About 50% of the time when I gave the rig throttle or reverse (a generous amount not just a little tap) the rear motor would go and other 50% of the time, the rear motor would not go (in both cases the front motor was running freely). When the rear motor did not turn, I could get it to go by starting the pinion gear moving with my fingernail.

I also checked to make sure that the pinion was not just lose in the rear motor making it appear that the rear motor was not spinning- this was not the case, the pinion is on tightly and it is definitely the motor not moving.

Next, I inspected the rear motor itself. I have virtually no experience with mod motors. That being said, the brushes appeared too be okay (they didn't seem worn all the way down). However, I did notice that on one terminal of the rear motor, the braided copper cord that connects the brush to the endbell was green and corroded. This is not the case on the other 3 terminals of the truck. Could this be the problem? would corrosion be a sign of brush needing to be replaced?

As you can probably, tell I'm relatively new to the world of crawlers. My experience mostly comes from small electric remote controlled planes were there's one motor, usually brushless, and the prop screw write onto the motor shaft , so any help or suggestion would be appreciated!

Thanks

basher


ps I just tried it again after about a 30 min break and the rear motor is now working

[RCbasher]

Probelms back again. I thought about it some more- could it be the wires shorting out? It does seem to act like a spontaneous electric dig. But could the rear motor short if the front one doesn't? (I have the motors wires so that the power goes from esc, to rear, to front motor). Nonetheless, I looked for shorts but couldn't find anything. I did solder capictors to the both motors, but they' look fine.

Thanks again for any suggestions

[Culetto]

Sounds like its the brush conection. Cut the eyelets off your brush leads and solder them directly to the mount tabs, then solder the motor leads from the esc directly to them. Also check your brush springs to make sure they are not bound up and have plenty of tension to give the brush good contact with the comm.

[JohnRobHolmes]

Sounds like you could use a good comm and brush cut too.