Front motor gets hot on my scooter

SOURCE: shoprider sprinter deluxe do I need to put grease in gearbox where surts are ? front motor runs slow and hot. back motor is good

Hi again I checked shoprider site on you're model and there is no mention of a front motor it only gives a listing on a 2 HP motor plus I checked monster scooter parts only one motor in there parts listing.,.???? Have u got the correct model. u don't have to put any oil in the transaxle unless u have dismantled it ...not sure what u mean by front motor .???? Cheers

Testimonial: "Thank you, The scooter has two motors, One in the front drives the steer tires and one in the back drives the rear tires. Sitting on the seat there is a motor in front of my feet and another behind my feet in the rear of the scooter. .When I took off the protector cap on the surt a puff of air came out.Not much ,but I heard it puff. The scooter ran like it was fixed for about 6 feet and then back to the slow mode. I unpluged the front motor and it runs fine off the rear.Plug in the front and it feels like 1/2 power..Had motor tested and it was fine..Thats when I seen the surt fitting and thought maybe it needed filled. Im going to check brushes next. Why would there be a puff of air when I removed the cap on surt ?"

SOURCE: my scooter

I don't know the answer but I will take a guess.

These mobility scooters use a lot of electronics. Switch mode power supplies are a way of controlling a dc motor more efficiently than with rheostats or the solid state equivalent, large power transistors. There are also electronics and relays to change the polarity for reversing and further electronics to prevent the scooter being able to reverse as fast as it goes forward.

When two motors are used they could share some of the same electronics or the electronics could be duplicated for each motor. While this would provide a fairly basic control there are some considerations, namely the front wheels travel further than the back when going around corners and during this the rear motor will be pushing the front motor and it will be acting as a generator.

The circuitry has a lot to do as apart from controlling each motor it must synchronise them so they consistently produce the same effort and at the same time allow the front motor to speed up slightly when cornering so the rear motor doesn't have to push it.

Clearly it is a requirement the two motors must talk to each other via the circuitry. While it would be better that each motor provides torque feedback, such a system would be complex and expensive and so it is more likely the current each motor consumes is monitored and synchronised via intelligent circuitry.

From your description I suspect the problem is a breakdown in communication between the two motors or the current monitoring or the synchronisation circuitry.
Usually scooter manufacturers assemble all the circuitry on a single board and seem reluctant to offer a checking and repair service, preferring instead to sell complete boards at inflated prices.

Double checking all the connections might produce results but the chances are you won't be able to go much further without a complete circuit diagram.