96 DS 48v Starts Great but Slow Top Speed

[tdgreenland]

1996 DS 48v SN A9601 480712

Recent Upgrades/Repairs:
Rear Seat
HD Springs
Larger Wheels/Tires
Batteries
Battery Cables – 4 ga
MCOR4 Conversion Kit
Solenoid, Resistor & Diode
Micro Switches
F/R Switch
Charging Receptacle

The cart takes right off when operated but is slow at top speed. I don’t know the actual MPH at full accelerator but this cart cannot keep up with my other carts.

Some history. Purchased used in 2016 with weak batteries. Only used the cart 3 or 4 times in 2016 and 2017 around my yard and it was very slow – I assumed this was due to the batteries not fully charging. Spring of 2018, cart would not move or charge. Put new batteries and battery cables in, still would not move. The rest of the upgrades listed above were done one by one with no success. The final thing done was the MCOR 4 conversion kit. Cart was up on blocks with wheels removed. Rear wheels would still not turn when accelerator was pressed. I gave the rear wheel hub a turn by hand while the accelerator was depressed and the rear wheels immediately began to turn (corrosion in the motor brushes?).

Could the cart be stuck in ½ speed mode? Is there some kind of speed sensor that could be bad? Weak motor? Could the MCOR 4 and pedal need adjusted better? Is there something I did not replace that could be the culprit? I am not attempting to speed the cart up beyond the OEM standards, just restore its speed to what it should be. I have too much $$$ in this to stop now and accept a slow cart. Thanks.

[Fairtax4me]

Guessing this is a series cart with the lever FnR switch?
If turning the wheel hub by hand made it start working the brushes in the motor are worn out.
It could have an issue with the half speed reverse. On the rear most micro switch on the FnR you should have a Green, Black, and White wire. Green on top, black middle, white bottom. Make sure those are in the correct order.
If so, unplug the green and white and jumper them together directly. This will bypass the resistor used for half speed (located in the black wire).

[tdgreenland]

Thanks for the quick reply. Yes, it is a series with lever FnR. So, if I bypass the reverse half speed micro switch to make sure that is not the problem, would you say it is time to rebuild/replace the motor? Also, with my research, I have not been able to determine if this cart has a speed sensor or not. Do you know if it does? I have read to do the roll away test to see if the sensor is bad. But, does a cart this old (1996) have roll away protection?

[Mooncarter]

It does not have speed sensor or roll away feature.

[Reddawg454]

A series cart shouldn't have a speed sensor.

[Fairtax4me]

No speed sensor and no roll-away function on a series cart, so none of that applies in your case.

If it's not an issue with the half speed resistor or microswitch. Then you'll want to check the throttle signal getting to the controller to be sure it's getting full throttle command from the MCOR.
And if that checks out OK, then I would pull the motor out to check the brushes.

[tdgreenland]

Thank you all for the help! I think I will pull the motor for rebuild or replacement.

[tdgreenland]

Pulled the motor and had the brushes replaced. Cart still not top speed on level ground and is very slow going uphill. Could this be the motor magnets? The controller? I have to figure this out because most of the cart has been rebuilt and I have a lot of $$$ in it.

[Wakko47]

Why not download a speedometer app and check actual speeds?

[Mooncarter]

Yes. As asked above, what is the actual speed on flat ground?