Cart Still Running Hot, Still need help, please

[Sergio]

Maybe You mistyped the previous post...

The easiest procedure is to hold one of the rear wheels stationary, You then need to make two full revolutions of the other wheel in order to get the correct ratio.

On a open differential design, because of the spider gears, You need either:

One full revolution of both wheels.

or

Two full revolutions of a single wheel.

To get the correct ratio on the motor shaft.

[MyCousinVinnie]

Now I am really confused because I was told to turn it once - by two different people.

If I do it your way, it's a 12:1, roughly. If so, that still doesn't explain how I got the increased speed.

Looking back around this site, there are about three different ways to do this, and they are all different and will all probably produce different results.

[Sergio]

I think 12:1 is correct for Your cart.

I am not sure why everyone thinks it is such an incredible speed.

According to the speed calculator and based on your setup, 4600rpm seems possible.

[MyCousinVinnie]

Well, they have the gear out now. Is there a way to count the teeth or something so that I can verify what it is?

Also, I agree with you on the speed calc. I have looked it up on more than one site, and I get 4500 rpm, which isn't too bad. Maybe too hot for a stock motor, but not for upgraded motor maybe??

[Sergio]

You should be able to count the number of teeth on the big "Ring Gear" and divide it by the number of teeth on the smaller "Pinion Gear" to get the ratio.

I am certain of the procedure I posted, that is just how open differentials work.

I read through Your posts (and previous thread) again, and there was one post You mentioned that You have tried a 3rd motor on Your cart from the shop that also overheated, is that right?

Did You purchase the Bandit with a new core or is that Your old core they used?

[MyCousinVinnie]

I was wrong they don't have the gears out now. They did count the larger gear though when they opened it. It had 70 teeth. Didn't count the smaller one.

Here is the motor history after installing all the new upgrades:

36 volt stock motor for about a year. It burned up while the FSIP controller was set to 700 amps and CA set to factor settings, which was 1.2 secs, I believe.

Tried a 48v stock motor. It heated up significantly over a one mile or maybe slightly less trip - over 190 degrees.

Then, purchased a Bandit motor with new core. Turned controller down to approx 500 amps and turned acceleration all the way down. Still hot. Cart gets about 22-23 mph now.

Tried the gear ratio test as described above as I was told. Per the method I tried it is 6:1. Yours would indicate 12:1 or thereabouts.

I have backed completely off the brakes.

[Sergio]

The rear axle twisting or rotating while driving could cause the brakes to drag, but you should be able to feel the hubs hot when You stop.

You may want to check the axle U-bolts anyway just as a safety check.

Since so many different motor cores were used (with same symptoms), we can can delegate heat induced winding damage to a low level probability.

The only other thing I can think at this time is some type of "Field Weakening" is taking place.

Does Your controller have an A2 terminal that is being used?

Can You post pictures of the Controller, Motor and FNR connections?

[MyCousinVinnie]

Will do on Monday

[MyCousinVinnie]

Cannot get pictures to work. I've checked the rear end of the thing. There aren't any issues with it as far as we can tell. I'm still lost as to the correct way to measure a gear ratio. I think I am just going to open it up and count the teeth. Every single internet resource out there says that if you have an OPEN differential, then you must rotate the wheel twice if you are either holding a wheel or you have jacked up only one wheel. That applies for cars. I don't know why it wouldn't apply for a golf cart. A differential is a differential. I am thoroughly confused, though. I can tell you that much.

[ridepate]

I'd count teeth and divide. No way to get that wrong!