Legacy Gem a.c. motor success stories😎

Many of our a.c. kit customers encountered stumbling blocks. Mostly due to variations in models, gears, or tires size.
We have had many successful conversions, but only hear about issues.
I would like to see some good reviews and positive suggestions.
Please start a new thread for questions or support.

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I converted a 2008 Gem. The car lived in a comunity that the Hills pretty much rendered a DC motor Usless.

The AC motor conversion saved this gem and made it a legit option for going into town with 4 people.

The Motor and Sevcon S4 made this car do what it was entered to do I give the conversion 2 thumbs up.

Mike and David have done a awesome job at sorting the kits issues out.

I have done personally done AC conversion on the following:
2000 E4
2009 E2
2008 E4
2008 E4
2016 E4
2008 E6
2010 E6

I can say that this is an awesome conversion. All the classic cars are getting very old, controllers are failing, motors are failing. This brings those parts back to 2020 standards plus enhanced speed, power and efficiency. It does take a little mechanical know how to get the motor in sometimes but the rest is pretty much plug and play. Plus I think we have a pretty good reputation for support and guidance to help you.
Hope to hear from some others - @BadBrad @Erniea15 @JarJarJava @Matthew_Cotten @diymatt @Monkeyron @bundcur

I haven’t finished mine yet!! But I have no doubts that Mike and Dave know what they are doing,
The guide they sent me was like if they had the car in front of them. Very detailed!!

2 Thumbs up here in the success stories category.

Gem Profile pre-AC install -
2000 4 seater
R4F Motor
T2 Controller
Chevy Volt Lithium
Chargery BMS
8:1 gear box
Factory suspension

Usage - The grocery store and local parks are pretty flat and easy to get to. If I want to go anywhere more than 2 miles (e.g. the important places like my kid’s preschool and the wine bar (not all in the same trip of course ;)), I have a massive hill I have to get up and over. Probably not as bad as @grantwest but close.

Problem to solve - With the R4F motor and acid, I got stuck climbing the hill because of voltage sag… sat for 15-20 min and was able to limp home. That got me putting in lithium. RF4 and lithium, I did ok but you could tell the motor was working hard and hot. Part of this problem was the 8:1 gear box and the DC setup.

Saw the early threads on AC and I wanted in right away; I think i was one of the early adopters so I knew it wouldn’t be perfect going into it. I’m willing to tinker and 1/2 of the fun with the GEM is working on it so I dove head first in.

Conversion Review - The car performs like a DREAM. There’s still a little tuning to do that @inwo and @MikeKC are helping with but nothing I haven’t learned to drive with. The GEM RIPS up the hills and I’m still yet to find the top end because I can’t find a long and safe enough stretch to push it over 45mph. The performance is AMAZING and I’m not having the heat issues I was having with the DC setup. @MikeKC and @Inwo were awesome at support and help. I honestly can say they would usually get back to me within 24 hours if I had questions (which can say is better than some of my direct reports at work… haha).

General thoughts and commentary about the install for an early GEM

  • 2 big challenges for the early GEMs.
  1. most folks are using the 8kw motor and Gen4 Sevcon controller. I couldn’t figure out a way to make the 8kw AC motor fit without replacing the frontend with a newer GEM like @bundcur did. @Inwo was able to help me find a 5kw motor that would fit by moving the shock mounts. The issue with the early GEMs is the differential/gear box is mounted dead center to the frame where later GEMs it’s offset to the driver’s side which accommodates a longer motor.

  2. Most of the electrical components for an early GEM are under the dash and not split between the dash and hood like in the 2005+. If you’re going to try to keep that configuration, the space is tight, tight, tight… and makes it tough to do any real clean and orderly cable-managment. The Gen4 footprint isn’t far off from the T2 so it’s workable.

My summary 2 thoughts on this

  1. From an A/C conversion perspective, complete win and success story.
  2. From an early GEM owner’s perspective, does it makes sense to go AC? probably not… But if you do, it will be awesome. Let me explain -

If you have a stock early GEM, you’ll have to dump so much into it to make it an great platform, you’re better off selling it and getting a later model. @grantwest actually said that a few months after I bought mine (circa 3-4 years ago) when I joined the forums and was thinking about modifying it… he was right from an economic perspective but I learned a lot and had fun so I chalk it up to a win! (@grantwest, you still can have an “i told you so” moment") I bought my 2000 for ~$1600 and have 10k into it… none of that is cool cosmetics, mostly various motors, batteries, shocks, etc.


Quick and easy upgrade to AC. I think the best setup/kit out there.
2008 Gem 2 Seater
Chevy Volt Lithium
Upgraded wheels tires

I was surprised by how quick and easy the upgrade was. I had mine up and running in around 3 hours. I knew my way around swapping motors and changing out the speed control and the directions and a YouTube video really shows how easy it is. The kit was programmed perfectly for me. 35 Miles an hour and smooth start in Low. Really nice start in High and Maxes out at 45 +/-.

This fixed a lot of my concerns with my updated GEM Car. Now I don’t have to worry about over RPMs on my motor or the speed controller melting away.

Not many of these in Saint George so I get a lot of looks driving around town and keeping up with traffic is such a nice plus. If you are thinking about it I would say Go For It. I’m sure you would love it as I do.


how much cost the conversion? and what include.

Did Mike ever get back to you? I believe it’s about $1700 for a 2005 to 2015.
Includes everything to plug in.

Sorry - this fell off my radar.
Yes as David stated above.
New Sevcon Gen4 AC Controller
New AC 8Kw motor
Controller Programming
PCB board to use factory GEM switches, wiring harnesses
Phase Battery Wire Cables

Thank you for your respond.

What is the top speed can get with the convertion?

Thank You

This depends on your gears/wheels/tires but - 12:3 gears = ~50, 10.3 gears= ~60

I have a 99 4 seater with a single 18s Gen 1 Volt module. I have a couple complete packs lying around but don’t know what my best plan of attack is. I have it running fairly good now after cleaning throttle contacts (error code 11). Have the module in the front and nothing under the seat yet. Should I switch to 96v instead of wasting time with limitations of the 72v? I haven’t found the spoof yet for overvoltage, I think that’s the main issue. I have a Thunderstruck 2500 charger and just ordered the Thunderstruck BMS today. Should have less than $4k in the whole car! Is that the best plan of action and what do you have to make this easier?

72 volts is fine, the problem is the 18s battery is 66 volts nominal.
The next step is 24s 88v nominal. 2p24s is perfect for high performance. I make a harness to parallel them.
I don’t know anything about the bms and charger. Can you set it for 18s to 24s?
The DeltaQ have up to 10 lithium profiles, a better choice IMO. ~$350 programmed.
A 24s 300 amp smart bms is <$150.

Where do I find those gear boxes ?

I have a 2001 I got from auction for $1400. It needs new batteries. Am I better off just getting a newer model so it works better with your 8kw motor conversion instead of messing around with this older 2001?

I would not spend that much money on an older Gem, but that’s just me. On the other hand, nothing to lose. I do have a shorter motor that will fit.
Newer Gems have disk brakes and more room for motor. Better charger, suspension, and controller mounted in a cooler spot.

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the brakes on a 2001 are horrible, you would not want to do an ac conversion on one. Get a 2005 and up, big difference in ride and braking.




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I guess I’ll just have to put some used batteries on this old 2001 to make it run and sell. Will be looking for something newer then Upgrade

Thank you guys for advises

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