# Required Hi-Po GE Motor Mods - Major?



## major (Apr 4, 2008)

badfishracing said:


> Tighter armature gap? How much?
> 
> Shaving about 40 pounds of extra iron. She's about #310 right now.
> 
> Are we on the right track?


Hey bfish,

I'd say so except for the points I left in the quote. I'd leave the air gap alone. You'll increase leakage and armature inductance which can screw with commutation. Also my guess is you'll push this poor thing to a couple thousand amps, so a few AT drop across the gap is not noticeable anyway.

But cutting the frame down Unless the GE motor designer had stock in the pipe mill, that steel is there for a reason. You want torque from this monster; leave that frame steel where it is. 

Regards,

major


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## Jimdear2 (Oct 12, 2008)

Major,

Thanks for the response. I also have a couple of questions. 

So I can get some idea of rear end gearing needed (the axle has a 5.14 to 1 in it right now and that is way too high), can you give me a guess, based on your experiance, of what kind of RPM we could see with this motor at say 220 to 260 volts. We have 20 usable Hawker 16 AH we plan to start off with. 

I was thinking of a series parallel set up with either a Soliton or Zilla and later some Headways so we would always be using high voltage as we progress.

We were also thinking of kevlar banding on the com. I assume that is done by turning grooves into the com at points where the brushes don't ride and tightly wrapping kevlar string into the grooves and then potting the material using some form of epoxy. Any hints or information you can give us there would be greatfully accepted.

Bad Fish wasn't really clear on the weight reduction plans. There are some large masses of metal on the end bells that would have no function in our and some areas that metal could be removed, We might do a clean up cut on the barrel just to make it "purdy", but no serious metal removal. We would like to get the motor down to around 280#.

Anything you can tell us about this motor would be helpfull. Because of the tire and weight limits for the class we are building for, we need to look at serious wheel speed. I would rather turn RPM into torque with gearing then torque into RPM. You can make things a lot lighter that way., 

Edit I'll add a few pictures 

You have a goooooooood day
Jim


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## major (Apr 4, 2008)

Jimdear2 said:


> So I can get some idea of rear end gearing needed (the axle has a 5.14 to 1 in it right now and that is way too high), can you give me a guess, based on your experiance, of what kind of RPM we could see with this motor at say 220 to 260 volts. We have 20 usable Hawker 16 AH we plan to start off with.


Hi Jim,

I don't know the particulars for this motor. And the RPM will be load dependent. So at the start before the load transfer, the motor load may be low enough with wheel spin to get the motor RPM pretty high. And with that high a voltage, you may need to limit it with a speed sensor feedback system to the controller. With that size motor and what I know about the application, my best guess is to use 4000 RPM as a max. Although it may hold together at 6000 or higher, I'm not sure why you'd need it.



> I was thinking of a series parallel set up with either a Soliton or Zilla


O.K. So you have a single motor. So you must be talking of S/P switch of the batteries. Right? In which case I think you're wasting your time. The motor controller has current multiplication, so at half voltage to the motor, battery current is half motor current. That is the same effect as halving the battery pack voltage with a parallel arrrangement, meaning each battery sees half the current.



> We were also thinking of kevlar banding on the com. I assume that is done by turning grooves into the com at points where the brushes don't ride and tightly wrapping kevlar string into the grooves and then potting the material using some form of epoxy. Any hints or information you can give us there would be greatfully accepted.


I wouldn't bother. Just like I said, use a RPM feedback to keep the RPM reasonable. I don't know if it is still on Jim Husted's web site, but he used to show a comm banding job he did on a 9 inch, I think.



> We might do a clean up cut on the barrel just to make it "purdy", but no serious metal removal. We would like to get the motor down to around 280#.


Yeah, they usually leave the OD of the frame as rolled, so kinda ugly. Who cares when it is under a fork truck? Truing it up which a finish cut is cool, if you don't get carried away. And prudy motors rule 

Good luck with it.

major


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## Jimdear2 (Oct 12, 2008)

Major, 

Thanks for the answers



major said:


> Hi Jim,
> 
> Although it may hold together at 6000 or higher, I'm not sure why you'd need it.


We are going to be tire limited in the class we have chosen. We will be using small 12x12x26 inch pulling tires. We will need to spin them pretty fast to be competitive. As I say I would rather turn RPM into torque when we need it then go the opposite way. Makes for lighter components.



major said:


> O.K. So you have a single motor. So you must be talking of S/P switch of the batteries. Right? In which case I think you're wasting your time. The motor controller has current multiplication, so at half voltage to the motor, battery current is half motor current. That is the same effect as halving the battery pack voltage with a parallel arrrangement, meaning each battery sees half the current.


Thanks for getting me back on track, I really know that. A while back we were considering a contactor controller set up. Since then I have decided on a controller but for some reason I never gave up on the series parallel switch. I want a lot of voltage at the beginning of the pull to get as much speed as possible while the weight is over the wheels, then switch to a lot of amps for torque as the weight comes down on the plate to keep the tires turning.



major said:


> I wouldn't bother. Just like I said, use a RPM feedback to keep the RPM reasonable. I don't know if it is still on Jim Husted's web site, but he used to show a comm banding job he did on a 9 inch, I think.


 I guess we will try without for now, may do it anyway just to be safe.



major said:


> Yeah, they usually leave the OD of the frame as rolled, so kinda ugly. Who cares when it is under a fork truck? Truing it up which a finish cut is cool, if you don't get carried away. And prudy motors rule .


"Purdy" can make a nice tractor just all that much more impressive. Might attract a sponser noe that there are new comercial electric lawn and garden tractors.

Thanks again for tour help.


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## DavidDymaxion (Dec 1, 2008)

Dennis Berube holds 2 NEDRA records with GE motors. He has done extensive mods to his GE motors. Sign up for the NEDRA list and post up a question there. http://www.NEDRA.com




Jimdear2 said:


> Major,
> 
> Thanks for the answers
> 
> ...


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