New to the Forum, about to buy a GEM without motor/controller..


:eyes:Been read this forum for a couple of days seems like a nice place!

I live in a community that has a lot of cart paths, some with hills some not. For 5 years been using an Ezgo TXT two seater. Been thinking about a teardown and stretch, doing something to the 36V drive train, suspension, paint, wheels…

Came across a 4 seat Gem I believe a 2007. It has been sitting outside for a few years, motor and controller gone, no batteries. Asking price $800…

I like the look of the Gems and so do the kiddos. Instead of messing with the Ezgo I am tempted to give this Gem a try. I’m very much a project type. Been playing with hub motors on bicycles. and Lipos for them. I have an aircraft maintenance background and understand a little bit about electricity, I play around a bit with micro controller, 3d print, Fusion 360 and yearn for a cnc…anyway.

What would any of you seasoned Gemster suggest for a Gem without motor, controller, batteries. Find a stock motor, controller?

I like the way an Ezgo RXV AC cart handles the native paths. And AC has a big appeal to me.
Speed is not important to me 20mph is plenty.
I am more interested in regen than speed…
I am more interested in NOT hearing the motor than going fast.

Mr Inwo, I have seen on ebay the AC motor that you have posted pics of and am tempted to buy one myself. Doesn’t sound like you have got yours yet to see if it would fit. Any thoughts on the compatability with a gem for torque, speed, gear ratio of the gem?

Thanks to All,

It comes down to finding a controller for an a.c. induction motor.
Sevcon can run it with the right tuning. It may be a long time before I get anything working.
Motor is rated 5000rpm. Best efficiency much lower. 20 mph is no problem with any gears.
The motor has 19 spline transaxle mount. Should bolt right up.

As the motor is so low cost, it leaves a lot in the budget for controller.
Curtis may have a simple control.
I’m trying the sevcon route first.

Thanks for you reply!
is the motor a 9 or 19 spline?
what voltage range input do you think it would be happy with?
Are you familiar with Navitas controllers? Specifically their TAC 1.0? The iOS interface looks easy…

Sorry, 19 spline.
80v rating. They were designed for 24s Life 200ah battery.
I’ll Google the controller. As of now, I’m concentrating on the sevcon.

Well I did it, felt sorry for it sitting there in the back lot

Just delivered

Looks a bit better after stripping the rain coat off and taking a pressure washer to it.

With no motor and all the electronics gone except for the charger I’m pretty open to what to put back in it. Think I’ll start with look see inside the gear box.

Perfect project for a $200 motor.
I can get you a $500 Sevcon controller for it, but it might be 6 months before I find a project to test it on.
Have the Sevcon and the file for that motor. I’m told it won’t work until fine tuned to vehicle.
If you can find someone to help who knows Sevcon, I will lend them to you or pay shipping to get it to you.
Can also give you a link to dl sw, and get you dongle and license.

Offer is good for anyone who can help me with this. I even have a 72v battery in an ammo box for power.

:slightly_smiling_face: I’ll help. I can put some batteries together that I use in electric bikes. I am ready to get one of those ebay AC motors, but the label in the picture lists the voltage at 49 and the rpm at 3090. Is that an issue? Have you received yours yet?

“Can also give you a link to dl sw, and get you dongle and license.” Yes!

I paid $500 for dongle and sw from Travis<
I can let you borrow mine if Travis will get you another license for mine.
I don’t know how that works. Ask him about Dave.

Motenergy tells me they were used on 72v ev at 5000 rpm.
Maybe you should use the Pmac motor. I have one, but ram-horn frame is in the way.
If you think it will help, you can borrow mine. They are $500 but far superior to induction motors.



The big arc on the right side is the problem? How much interference? I just started taking apart my front end.
How is the Pmac superior? Efficency, noise, durabiliy? What controller. I found on an electric car forum a German guy (engineering background) who has an open source roll your own controller for AC induction motor. Probably designed for much more power than a Gem needs but maybe can be toned down…

I might consider a mod to the frame

All my swing arm bushings are…not great… The service manual says that the bushings are not replaceable, replace the whole arm! Has anyone come up with a way to replace these bushings?

Taking the gear box out is easy. CV joints feel okay but the boots are cracking. What is a good source for boots?

Has the breather mod, bellows.

The Fill/Drain plug that gets some mention

The only major electronic part that was not previously harvested. Plugging it into 120 starts several of the lights flashing :slightly_smiling_face:

Yes, needs another inch.
Google Pmac. I’m no expert.


I found A arm bushings at NEV accessories in Arizona, nice people to talk to. Not too hard to press out and new ones in but you need something like a heavy duty “C” clamp to do it. Much cheaper than new A arms or even buying the bushings from Polaris.

Replaced gearbox input shaft. Not to hard to do.

The charger works! With some help from Inwo, there was no temp sensor, so a 10k resistor to ground fools the charger.

Decided to put in an AC motor and controller. GOOD decision. It just takes a bit of custom wiring to make it work.
Run/tow switch
power (from pack)
ground for solenoid
“Key switch” mine is just a rocker
Charger interlock (mine is bypassed)
Forward and reverse (used original gem switch for this)
Throttle, 5v in (from controller), ground (to controller) , and signal (to controller)
Foot switch ( in throttle assembly) activates solenoid
back up horn (did not use)

Runs very smooth and quiet. 4000 rpm at 20 mph (12.44 gear box, 21 inch tires)
Runs below 35C temp but it isn’t summer time anymore…
I believe the efficiency is significantly better than DC system. (generates less heat)

Went with some Lifepos from Inwo. Only about 60 miles on system but good so far.

His cells are strapped together in 10 cells per group. 3 groups fit pretty easy slid in from the back.
Would recommend shipping only 1 10 pack per box.( less evidence of droppage vs 2 per box)
I’m using 25 (may go to 26) for the main pack and will make a 12v system with 4.
This is only a 4800 wh system but with the AC motor I have a range between 30 and 40 miles.
No BMS at this point, cells are staying within 0.01v of each other, but still early in the game.

Over all thoughts.

Bypassing the original Gem electrics/electronics saves a learning curve on somewhat dated stuff. Probably saves money too on replacing expensive stuff that has better/ cheaper current alternatives.

However there is a learning curve on the new stuff and some customizing is required.

I think AC motors are a good choice. A Pmac is probably the best. But harder to install than an induction one. May be a “piece of cake” on a newer model (2013 & up ?) without the “rams horns” in the way.

I still have cosmetics to deal with.

Maybe some different shocks, at least on the rear…

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Wow that motor and controller look awesome.

So please excuse my ignorance. But how is the top speed. What have you noticed? Did you ever drive another Gem. What’s the advantage of the Burshless motor that you have noticed.

Can’t you see? He bought the motor and controller to color match the batteries. Doh!