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Old 03-19-2018, 09:47 AM   #1
Tools4u
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Default Ezego RXV brake problem

I have an ezego rxv 2012 that has a major problem with the braking system. Once the brake is press it stops but then goes back about 2 feet and settles there. It never stays where you press the brake. I have had people almost run over as the cart backs up. Any help please
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Old 03-19-2018, 09:57 AM   #2
cgtech
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Default Re: Ezego RXV brake problem

You probably have a Rxv with Curtis controller and high speed gears. This problem is why I avoid high speed gears in Curtis Rxv. How fast does your cart go? Is it a retired golf course rebuild? Do any of the badges say "Freedom"? If my hunch is correct, only solution i have found is get rid of high speed gears, and get speed with freedom mode instead.
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Old 03-20-2018, 10:22 PM   #3
Tools4u
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Default Re: Ezego RXV brake problem

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Originally Posted by cgtech View Post
You probably have a Rxv with Curtis controller and high speed gears. This problem is why I avoid high speed gears in Curtis Rxv. How fast does your cart go? Is it a retired golf course rebuild? Do any of the badges say "Freedom"? If my hunch is correct, only solution i have found is get rid of high speed gears, and get speed with freedom mode instead.
i did put the high speed gears in but i had the problem before i changed the gears. it was a retired golf course rebuild
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Old 03-21-2018, 02:54 AM   #4
BobBoyce
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Default Re: Ezego RXV brake problem

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Originally Posted by Tools4u View Post
i did put the high speed gears in but i had the problem before i changed the gears. it was a retired golf course rebuild
Sounds like more than gears... like high speed gears coupled with larger tires. The worst thing you can do to an RXV. cgtech is right, high speed gears have no place in an RXV. With stock gears, 20.5" tires are the largest I recommend. That is if you expect drivability and enough torque to climb hills, or even to go up driveways where I live.

The cure is to go back to stock gears and no larger than 20.5" tires, then use Freedom Mode to get the speed. The RXV is unlike common golf carts. The AC drive motor is the only brakes you have while driving. In order for them to be effective, the motor needs the correct mechanical advantage. That is the determined by the final gear ratio. Actual gear ratio in the rear end plus the tire diameter.

I almost made the same mistake after buying my first RXV. The new high speed gear set I bought is still sitting in a box here. I listened to cgtech, and am glad I did. He has RXV experience that I did not yet have. My experience was with controllers, road driven Electric Vehicles, and older Series golf carts. RXVs are unique.
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Old 03-21-2018, 03:55 PM   #5
Tools4u
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Default Re: Ezego RXV brake problem

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Originally Posted by BobBoyce View Post
Sounds like more than gears... like high speed gears coupled with larger tires. The worst thing you can do to an RXV. cgtech is right, high speed gears have no place in an RXV. With stock gears, 20.5" tires are the largest I recommend. That is if you expect drivability and enough torque to climb hills, or even to go up driveways where I live.

The cure is to go back to stock gears and no larger than 20.5" tires, then use Freedom Mode to get the speed. The RXV is unlike common golf carts. The AC drive motor is the only brakes you have while driving. In order for them to be effective, the motor needs the correct mechanical advantage. That is the determined by the final gear ratio. Actual gear ratio in the rear end plus the tire diameter.

I almost made the same mistake after buying my first RXV. The new high speed gear set I bought is still sitting in a box here. I listened to cgtech, and am glad I did. He has RXV experience that I did not yet have. My experience was with controllers, road driven Electric Vehicles, and older Series golf carts. RXVs are unique.
When I got the cart it had standard gears and 14” low profile tires. The problem was happening when I got the cart with this setup
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Old 03-21-2018, 09:03 PM   #6
BobBoyce
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Default Re: Ezego RXV brake problem

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Originally Posted by Tools4u View Post
When I got the cart it had standard gears and 14” low profile tires. The problem was happening when I got the cart with this setup
Of course it was. Someone changed wheels and tires before it became yours. I think you are confusing wheel size with tire diameter. Stock tires are about 18" diameter. 14" wheels with low profile tires can be anywhere from 17" rubber bands to 23" diameter less low profile tires. The chances are, your tires were already well above the 18" stock diameter. Likely why it suffered from that problem before you made it worst by switching to high speed gears. I'll try to explain it as simply as I can. Being an engineer, I tend to over-complicate explanations, sorry in advance. This is the nuts and bolts of what is going on...

It is a fairly common problem with cart owners. People like the looks of larger wheels and tires on carts so much that they often put them on without knowing what it does to the functionality of the drive system. The RXV does not have physical brakes at the wheels, so it is double prone to issues caused by effective gear ratio changes. Increased motor current required to accelerate is common to all carts, but braking effectiveness being reduced affects the RXV more than any other cart. With more speed, you need more braking effectiveness, not less. The proper way to speed up an RXV is to use Freedom Mode and to up the top speed setting, not to go with high speed gears. The RXV has a 16.99:1 gear ratio rear axle, and the lowest gear ratio intended to be used in the AC drive axles is in the 2Five. The 2Five is a road legal version of the RXV, and they added physical disk brakes to help with braking and to meet DOT motor vehicle safety standards. It also has a VCL (Vehicle Control Language) that is set up for its 14.99:1 rear axle gear ratio and 18" tires.

If someone wants to go with much larger wheels and tires on an RXV, they may need to consider changing out the rear end gears for a set with a higher gear ratio to compensate. This is why changing to tires up to 20.5" can be within the acceptable range for stock gears. More than that and the E-Z-GO factory VCL in the controller is too far outside of it's designed operating range. The motor RPM vs actual MPH is changed, and the controller cannot compensate for that without recalibration. Even if recalibrated, current draw increases due to increased torque loading. It affects speed regulation, which becomes more erratic. And that is exactly why the brakes start behaving erratically. The RXV is essentially a computer on wheels. It is more sensitive to sensor input changes than E-Z-GO Series or SepEx carts. Suddenly it finds its speed and current sensors telling it that it is going slower, yet drawing more current, and it has not been reprogrammed to interpret the changes. I hope that I was able to help you understand the issue. If not, maybe cgtech can explain it in a less technical manner.

Bob
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Old 03-21-2018, 09:23 PM   #7
Tools4u
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Default Re: Ezego RXV brake problem

bob, thanks for your help. at the moment i have replaced the low profile tires with 10” 65 tires for a,smoother ride. is there any fix like adding physical brakes that will work if i leave the gears the way they are.
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Old 03-21-2018, 10:41 PM   #8
BobBoyce
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Default Re: Ezego RXV brake problem

Quote:
Originally Posted by Tools4u View Post
bob, thanks for your help. at the moment i have replaced the low profile tires with 10” 65 tires for a,smoother ride. is there any fix like adding physical brakes that will work if i leave the gears the way they are.
Yes, there is an aftermarket front disc brake kit available for the RXV if you have 10" wheels, but it will not stop the cart from rolling if you release those brakes before the parking brake sets. Nothing will fix that other than going back closer to the stock gear ratio and having tires that are not too large. The problem is related to the distance rolled per pulse from the motor speed encoder. The controller cannot get a fine enough sense of distance (sensor resolution) with those gears. Here is a link to my first post about the brake kit. There are posts showing the brake kit install after that post.

http://www.buggiesgonewild.com/road-...ml#post1375913
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