5HP to 7.5HP Advanced Motor

Hi. Home someone can enlighten me. If I change the stock GEM 5HP motor to the stock 7.5HP Advances motor do I need to reprogram the motor controller?

Not normally. Depending on what you are trying to do it might benefit from a little bit of a tune but it should run.

It would help if you list the year and model of your car and what you are trying to do. Hopefully you don’t have an early Gen1 (00-04) car. You can’t put a long 7hp in those cars.

Also- Your other queries into purchasing controllers on the Buy/Sell pages are asking from fairly old posts. I’m going to guess that those are long gone.

Again, What seems to be the nature of your issue?

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Well I have the 7.5HP motor by Advanced Motors from a 2015 e4. When I install it on my 07 e4 the car runs slow. Acceleration is terrible and speed maybe 7mph max. Car runs fine with original 5hp motor. So I wonder if controller needs to be reprogrammed or changed to different model in order to use the 7.5 motor. The 07 e4 has the T4 controller.

Is motor new? Seems it has issues.

Not new, but seems to check out fine (quick resistance check of field coils and armature). Maybe brushes…

But does anyone know for fact if controller programming is required when changing from 5HP to 7.5HP motor so I can rule that out?

Uodate: I guess I missed where @AssyRequired said “not normally”. So must be the motor…

Seems it has issues.

Yep- I sense that too.

@ilov2xlr8 -
What is the history of the 7.5 motor/donor car? Did you do any service/inspect this motor before the install?

It sounds like you have a stuck brush. When this happens you are only working off half a motor.
These motors have two sets of brushes, and two sets of field coils set up 90 degrees apart from each other, which means you have two motors in one housing.

They also don’t like to sit for long periods of time.
A stuck brush will eventually lose contact and start arcing with blue plasma fire. More visible under big loads. You may hear a sound coming from the motor much like the sound of sizzling bacon and even smell it as fresh ozone.

If you continue to use it in this state it may damage your motor beyond repair and the huge voltage spikes from the arcs have been known to kill your controller by taking out the FETs(see codes 57 and 66). You may also tear open a hole in space/time usually causing a bunch of your left socks to disappear from your dryer.

Crap! Might be too late - some left socks already missing!

I got the motor used. Don’t know the history unfortunately. I’ll take a look at the brushes. Thanks for the insight.

The following should be read with the voice of Rod Serling…

Imagine if you will, the scene where a Gem owner is driving his car thinking, “Wow- this car is driving so awesome. I think I will pull this 7.5 motor out sell it so I can put in something else.”

Then you can also imagine that super hot group of ladies is looking over and flirting with you and not at Jason Momoa sitting with you and tossing back a brewski.

or Jason Momoa sitting with you and tossing back a brewski.

Sure, anything awesome can happen.

What about the thermal sensor? The one installed in the motors. They all have one. 2 wire connector. What does the controller do if it’s bad? Does it not run the motor at all or runs it at reduced power?

OK I have good news. As I suspected, it was the motor thermal sensor. I disconnected and measured the resistance across the thermal sensor on the motor. It was open! The good sensor on the 5HP motor reads about 1 ohm. I tried driving the car with the sensor disconnected and the car behaved the same (slow). I then connected the known good sensor from the original 5HP motor and the car took off full speed!
So the controller does limit the motor power in case of motor thermal sensor failure. Makes sense.

I guess you didn’t happen to notice that you maybe had a little red thermometer light on your dash after your motor swap? That would have been good to mention.

Good that you found it, Bad on me for not asking.

Yes, the GE controller does limit the speed when it detects the motor is overheating. Most people just bypass that temp sensor and connect the two wires together. It’s a thermal switch. Either on or off.

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I didn’t. I am curious now though and will check.

Yeah I confirmed that the thermometer icon was on with bad sensor and off with good sensor.