Digital Overdrive Systems

Home of the original 'SpeedyLink' Club Car OVERDRIVE System

High Speed Golf Carts: Choosing Your Options by Randy Wade

Electric Low Speed Vehicles (LSV’s) are becoming tremendously popular these days for a number of reasons. They are quiet, fun and relatively comfortable to drive, but more importantly, they do not use fossil fuel. The other thing is; they typically are set up to operate at really slow speeds (12 mph or so). You guys that have rented golf carts at your local course know why they do that. To operate on public roads and be categorized as a LSV, many municipalities require the vehicle to go 20mph, and must be equipped with lights, seat belts and a horn.
The lights and belts are pretty easy to deal with but getting your cart to go 20 mph is another story. Even if you are not trying to make it street legal, most users want the extra speed capability just to add more usefulness and enjoyment. 12mph is just too painfully slow for most users. If you think that 12mph is fast enough, give it a few weeks.
OK, so you are ready to do whatever it takes to make that baby fly. Well maybe 20mph isn’t exactly flying but it will sure feel like you were if you get dumped out at that speed. Safety belts are a good idea at any speed. The first thing to determine is how fast you really want to go and how are you going to use the vehicle? Is the terrain flat or hilly? Will you be hauling cargo of any substantial weight (No, I don’t mean your mother-in-law)?
For hills and/or heavy loads, you will need to also increase the torque of the cart. This means a more powerful motor and probably an upgraded motor controller to handle the extra current demands of the motor. There are several vendors that can supply such upgrades, but they can get expensive. Be sure to do your homework and shop around.

If you have just a standard cart and use it on basically flat ground, you have a few more options:

Taller Tires – Increasing the diameter of the drive tires increases the distance they will roll for each revolution of the axle, thus increasing the speed your cart will go. You first need to know how fast you can go with the standard 18.5 inch tall tires. Most portable GPS units can be used as a speedometer to find that. If you don’t want to crunch the math, there are several free online calculators to help you determine how much speed you will gain with the new taller tires, based on their size. See below for our free calculator tools which can be used to find the various relationships between speeds and diameters. Although increasing the tire size will increase you speed, the torque will suffer somewhat. That means you may have to leave your mother-in-law home! Tire size is also limited by the wheel opening. Most large tires require the cart be “lifted” which may not always be desirable and can be costly and the speed gain is relatively small (a couple of mph increase)

High Speed Gear Set – In the differential housing or rear axle reside a gear reduction system. The motor has a small gear that drives the axle’s larger gear. Typically the motor rotates about 12 times for every one revolution of the axle. This is how the relatively low power motor gains a mechanical advantage to propel the cart. Like the gears on a bicycle, it is easier to pedal when the drive sprocket is on the small diameter one. To go faster, you need to advance to the larger drive sprocket. The bike goes faster, but it is harder to pedal. In a golf cart speed gear set, the ratio is similarly changed by increasing the drive gear diameter, and the cart runs faster. Like the bicycle though, the motor has to provide more force “torque” to the axle. This type of modification is great for speed but will sacrifice low speed torque (your mother–in-law again) and is not recommended for hilly areas. Installation can be messy due to the gear lubricant and requires some skill and knowhow.

Increase Motor RPM – Increasing the Revolutions per Minute or RPM’s of the motor is one of the most popular techniques for increasing a golf cart’s speed. This type of modification does not sacrifice low end torque like the two previously mentioned ones. Golf cart electric motors are designed to operate at a certain maximum RPM (typically around 3600 RPM) at either 36 volts or 48 volts and provide a good balance between speed and torque of the end product. Aftermarket motors have their field and armature windings redesigned such that they achieve greater RPM than the stock ones. If the motor spins at twice the original RPM, a 12 mph cart could reach as much as 24mph. The motors are safe and reliable but can require the addition of a high current Controller to operate at full potential. Aftermarket “speed motors” are available from a number of vendors but can be rather expensive due to all the copper wire in the windings. There is one vendor that provides a really simple and easy upgrade for Club Car IQ carts called a SpeedyLink, which increases the RPM of the stock motor without any additional modifications.

Whichever method you use to increase the speed of you golf cart, be sure to use good judgment and utilize proper safety equipment. Carting can be fun and functional for everyone and has many applications. Be safe enjoying your fast golf cart. Watch for more articles about golf cart upgrades and maintenance.

Free Speed Calculators

Calculating the speed after installing bigger tires on your Club Car (or anything else) is easy if you have a few pieces of key data. Say you have a cart that goes 13 MPH and you want to know how fast it will go using a larger diameter tire. Enter your known speed with the tire diameter first. That will tell you the axle RPM. Use the axle RPM in the next box along with the proposed tire diameter and you will get the new speed, or with desired speed find the tire diameter needed. Remember though, these are "ideal" calculations. Going to too tall of a tire or high of a gear ratio, will affect your torque (acceleration ability) and some motors may not be able to supply enough torque to achieve the calculated speed.

Use this calculator to predict Tire Height, MPH or Axle RPM. Be sure to retype the correct Axle speed to get an accurate comparison in the second or third row. Mouse click on the yellow for the result.

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Motor RPM can be calculated if you know the Gear Ratio of your Differential (axle). Axle Ratios are usually written like: 6.5:1 (six point five to one) or 8:1 (eight to one). All this means is that the motor rotates 6.5 or 8 revolutions for every one of the axle. (Precedent Club Cars have a ratio of 12.3:1) This is how the motor gains a mechanical advantage or leverage to propel a heavy cart. Many different ratios are used by the various cart manufacturers. The increase in the mechanical advantage equates to the torque of the system. Obtaining good top speed, while retaining sufficient torque to get your cart moving quickly is a delicate balance . This balance is a key part of the performance design of any vehicle.

Use this calculator to predict Motor RPM, Gear Ratio or Axle RPM.

We hope these calculators help you with your project and stir your interest in our product. If you need big torque, you will need to upgrade to an aftermarket motor and controller. There are several vendors that offer excellent motor packages like Plum Quick and D&D, but, if you just want a little more speed, increasing the motor RPM with a SpeedyLink is our best bet. The SpeedyLink can increase stock motor RPM significantly (up to 50%), without loss of torque or harm to the motor.

Digital Overdrive Systems

Free Speed Calculators

Use this calculator to predict Tire Height, MPH or Axle RPM. Be sure to retype the correct Axle speed to get an accurate comparison in the second or third row. Mouse click on the yellow for the result.

Use this calculator to predict Motor RPM, Gear Ratio or Axle RPM.

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