# DC Series Motor Rebuild for Golf Cart to Dune Buggy Conversion



## adamj12b (May 4, 2009)

Hello everyone,

I am hoping someone could give some pointers of rebuilding the motor out of my golf cart to make it like new and improve its performance. I bought the golf cart cheep ($250) on craigslist earlier this summer. It is a Columbia Par Car. I have been using it as a test vehicle for Pauls open source motor controller. So far It has been wonderful. 

So what I am doing now is working on building the golf cart into an electric dune buggy! To accomplish this, I hope to replace the six 6 volt batteries with six 12 volt trojan flooded batteries, or if I can convince the wife...24 TS 90AH cells. This would work well because It is very hard to get the motor to pull 270 Battery Amps without just standing on the brake and the gas...

Anyways, I took the motor out of the golf cart tonight and took it all apart. It is a GE motor. Ive dealt with RC car motors so this isnt that much different, just a lot bigger. It looks like water has gotten inside the case and has corroded the inside of the rear end bell. There are 4 brush's that have H100 engraved on the side of them. 2 + and 2 -. They have good length left, but the ends of them are very chipped and pitted. So I would like to replace them while I have the motor apart. The brush's would be either http://www.evparts.com/prod-BR1924.htm or this one http://www.evparts.com/prod-BR1923.htm. I think its the first one because it have the 4 brush's. Another thing I was wondering about would be springs. Is it possible to twist them around another rotation to increase the force that they push the brush int the com. Would that be better, or would it cause problems? I found them http://www.evparts.com/prod-BR1931.htm. Cheep and easy to replace. another thing to refresh the motor. The brush holders look to be in good shape, but again http://www.evparts.com/prod-MP1110.htm , so i could replace it if needed.

Now I need to know what I should do to clean the com of the motor. Its not very rough, but if you look from the top down, some of the bars are very dark...

What about timing? The motor has fix'd timing right now with only 2 holes drilled in the can of the motor. I can easily drill and tap new timing holes in the can so I would just need to find out there they need to be? Would that work?

Last question, Could this motor handle twice the voltage at about 72 volts?? If it helps, the differential is about 2:1 ratio. The golf cart right now tops out on straight road at 18 MPH. So with the 18" diameter tires, that is about 672 RPM at the motor...is that right? If that is the case, And I can keep the motor cool, should it handle 72V?

Here is a link to the photo album of the motor pics. http://www.flickr.com/photos/adambrunette/sets/72157623017444385/

-Adam


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## major (Apr 4, 2008)

adamj12b said:


> ....Brushes....
> So I would like to replace them while I have the motor apart.


Hi adam,

I'd reuse the OE brushes unless they are very short (worn down) or cracked or otherwise damaged. Chips on the edges may not be a concern, brushwise, however may indicate a problem with the commutator, like a raised bar. Aftermarket brushes can be of low quality.



> Another thing I was wondering about would be springs. Is it possible to twist them around another rotation to increase the force that they push the brush int the com.


It may be possible, but do not do it. I think the motor designer knows better the proper brush pressure than you. All you would do is increase the friction force causing more heat which could damage the comm and possibly the rest of the motor as well.



> Now I need to know what I should do to clean the com of the motor. Its not very rough, but if you look from the top down, some of the bars are very dark...


Unless there is a problem with the commutator, leave it alone. To tell if it has a problem, you should use a dial indicator and measure the runout and bar to bar deviation. Other comm problems can be burned or dragged segments (bars). But the color (patina) is the film, which is a good thing. Do not clean it off. Otherwise you're in for a long breakin period. If the comm needs service, it would be turning and undercutting by a professional.



> What about timing? The motor has fix'd timing right now with only 2 holes drilled in the can of the motor. I can easily drill and tap new timing holes in the can so I would just need to find out there they need to be? Would that work?


I suppose, if you need it.



> Last question, Could this motor handle twice the voltage at about 72 volts??


I suppose.



> If it helps, the differential is about 2:1 ratio. The golf cart right now tops out on straight road at 18 MPH. So with the 18" diameter tires, that is about 672 RPM at the motor...is that right?


It does not sound right to me. Likely your ratio is a lot higher than 2:1.



> If that is the case, And I can keep the motor cool, should it handle 72V?


It is a totally enclosed motor, so cooling may be a problem.



> Here is a link to the photo album of the motor pics. http://www.flickr.com/photos/adambrunette/sets/72157623017444385/


Just noticed your pictures. Brushes and commutator look good to me. And this must be an old motor. I don't think GE builds them that well anymore.

Regards,

major


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