Ludicrous Speed question - 2002 GEM E4

Hey all - I picked up a 2002 GEM E4 yesterday, and it is pretty awesome, but I have a question about the speed…

First, it has upgraded wheels with 205/50 R15 tires, so I am sure that is part of the answer to my question, but… When I am in turf mode, the thing drives like a normal GEM - it does about 28 MPH, and range appears to be pretty good so far. But if I put it in Road mode, the thing does 36 MPH, and the accelleration is insane… It will put you back in your seat. And it appears that it sucks the battery pack down very quickly - I think the total range when driving that fast is about 5 miles. It is honestly too fast for me, so I plan to leave it in Turf mode.

It has a 7.5HP motor, and what appears to be a standard controller…

Does anyone have any idea what may have been done to juice this thing up so much?

You just said 2 of the 3: big tires and a high rpm motor.

The 7.5hp is likely either a D&D or Advanced. Possibly sold rebranded by R$F. Anyway, it’s a 5000RPM motor that you can spin to 6k all day long, especially the D&D (blue).

Your tires are 23", take 0.5" off for the weight of the vehicle pushing down.

The controller (t2)was reprogrammed to let you get that kind of speed and tweak the performance. If the motor is an R$F then they probably did the programming, it’s included with the motor purchase.

What I used to do with my 02 was I’d flip to road mode to merge or if I had to deal with fast traffic, then flip it back to turf because, like you said, the motor will suck the batteries dry quickly at that speed.

Get a goliath battery to match goliath appetite.


Can you give us some background a to who built it?
Did the PO do it all? Or did he hint where it was done?
Or is this one of Dustin’s cars?

Dustin? Really? THAT Dustin?

@AssyRequired - the motor is in fact blue… see attached pics. It is a little tough to read the label, but maybe it looks familiar to you.

I haven’t the foggiest idea who built it. It actually looks like is was left outdoors in the Phoenix heat for a while before it was repainted.

I will see if I can figure out what controller is in it. Man… this thing is waaaaaay awesomer than I thought.

@AssyRequired - Wait… I just remembered I have the title from 2 owners ago. Johnathan Strickland from Villa Rica, GA. Purchased it in 2016. Prior to that it looks like it was titled in TN.

Does that ring a bell?

Names don’t ring a bell, Others might know these names. Not important, Just curious if any build info was passed on with the car. It looks like somebody did a nice job on it from what I can tell so far.

Except for this -
What is this orange wire? if one end goes to the big cluster on top of the controller marked B- (I think it does) and the other end attaches to that screw on the dash? Not that I like to mess with a perfectly good working car without a full inspection to see what is going on, but you should probably remove it and see if something else stops working.

This looks to me like someone thought it would be good to tie -72v to frame. This is never a good idea!! Not to mention that -12v is also there to run a few accessories.

So- Remove that orange wire, then measure from B+ to frame and see what else may be tied in somewhere. If you get traces of a little bit of power then it is back feeding in from some component (DC Converter?) and probably Ok. If you get a strong 72v (or higher) then you need a look at how the batteries are wired.

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The motor is a later/current Ride 4 Fun. R$F gets the motors from D&D and rebrands then.

Count the pins on the small connector on the controller. If it’s 8 it’s a T1. 12 is a T2.

Never seen that charger before though

Never seen that charger before though

Yeah, I might have to look that one up. It looks like it is in there a little wonky. Make sure it is secure.

And what up with that firehose/strap coming off A2 and going around the motor? Maybe the brush inspection cover was rattling?

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Great feedback… The charger is definately an aftermarket, and a little wonky. It is an Eagle Performance 7212, and it has a “remanufactured” tag on the cord. It has not been fully integrated into the wiring of the cart, and the 120V plug is simply hanging out of a port under the dash area.

Interesting point about that connection to the frame… I will check that out. There are a bunch of under-frame LED’s that may be usung this as the ground source, but I am not sure. I will check it out and let you know what I find.

Ok - @JarJarJava - Based on the 12 pin connector - I am going to say this is a T2.

@AssyRequired - I was able to step away from conference calls for 10 minutes to look at that frame ground issue. It looks like the previous picture just lined up the connector with the orange wire. This connection actually goes to some aftermarket wiring as far as I could see in the short time I had. I will investigate further later, but I am guessing it is for the under-carriage lights.

But it did open up a couple more questions. There were two important-ish looking connectors with no home. Does anyone recognize where these should possibly connect? One looks kind of like an s-video plug, and the other is a 2x4 connector.


Charger Looks beefy-

The manual:

That’s the temp sensor and pod led connection from the old Zivan battery charger.

I agree with JrJava,
The round DIN plug went to your old charger. It drives a little LED on your dash pod(grey cable), and also had a temp sensor (black cable) that runs forward to a tube the size of a cigarette butt that tucked in between the batteries.

Looking up that 2x4 connector…

Ahhh… I saw that little cigarette butt sized sensor as well and wondered what it was. So that was used to shut down or modulate the charger if the batteries started getting warm?

It just varied the final stage finishing profile a bit based on temp, You could run without it. Not all chargers require it. Even the charger it came with didn’t have to have it connected to work.

This is our build - Ride-4-Fun - We worked with Jonathan Strickland in 2016. Attached is a picture of your car before it got painted and detailed out.

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Wow - very cool. I may ping you if I run into issues that I cannot figure out.

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Next battery swap I can help with that.