DC Contactor Problem - Needed

Hi All, I have a 1999 48Volt Rev2 that has motor shudders issues in forward and will just not get up to any kind of speed. Reverse has plenty of power. Replaced the potentiometer and no change (thanks to all for the part information!). Is the culprit the SW80-684 contactor or perhaps the DC88-271E forward / reverse contactor? Anyone experience the same issue?

I cannot locate either of the above referenced contactors - all help is appreciated.

Could be stuck brushes

And how would I go about un-sticking the brushes? The vehicle goes fine down hills and in reverse…

you have to take the motor apart.

Try this first

Swap the armatures on the motor Reverse will now be forward. If it runs ok then its not the motro if it still shudders then its probably the motor.

I’m not up to speed on 48 volt carts but a 99 should be 72 volts the last 48 volts were early 98.

Does it have a series motor? The lables on the small wires would be marked S1 and S2 On shunt motors the lables ar marked F1 and F2

Do you have seperate solenoids for forward and reverse? If so can they be swaped?

Attached are photos of the motor and contactors. Can you offer a direction on the easier way to reverse the motor as you suggested on your response?


Reverse the armature leads on the motor

So: S-1 to S-2 and A-1 to A-2 (and of course A-2 to A-1 and S-2 to S-1)?

Many thanks.


Only A1 and A2

If you switch both sets rotation will not change

Thank you sir, will do and if motor is bad - do you sell replacements?

I do but don’t have any series motors.

I charge $125 to service a motor if it’s repairable. Plus postage both ways


Swapped the leads and it again shudders / will not get up to any speed. Brushes must be shot. Appreciate all of the advice and assistance.

There is a 2.6HP motor on Ebay to fit your 48 volt car.

Did you check your brakes for dragging? Jack up all 4 corners.


I did. Wheels move freely. Motor “bucks” with accelerator depressed. Fine at very low speed…

You better quit and repair/change out the motor before you lunch the control


Will do and appreciate all the advice. Great forum.