Center of Gravity Stand
COG Quick Check
The Center of Gravity Stand allows you to quickly and easily find your car's center of gravity (COG) without rulers or pencils. This is a super simple and very accurate tool for determining COG. Instructions and tips included.
What is COG?
The center of gravity of your car is expressed in inches. It is the distance from the rear axles to the balance point of the fully assembled car. That balance point should always be in front of the rear axles and is usually between 1 to 2 inches.
The exact location of the COG of your car can be determined with the use of the Derby Monkey Center of Gravity Stand as follows:
• Set the Center of Gravity Stand on a flat and level surface.
• Carefully lay the car across the balance beam.
• Move the car back and forth until it balances.
• Visually align the center of the axle head to a corresponding mark on the measurement scale.
• This will indicate the car's COG in inches.
• This distance is how we express the COG location on a Pinewood Derby car.
Where Do You Want Your COG?
Many people simply tell you to just “put the weight in the back”. While that is true, there is a lot more involved in this process. Proper placement of the COG is crucial in order to have a fast car.There are many different opinions regarding the pinewood weight placement and where the exact location of the COG should be. However, every one aggrees that you want it close to the rear of the car. Most publications recommend a COG of 1″ to 1½” in front of the rear axles. Most experts agree that this is too far forward. The faster cars seem to be built with a COG of a less than 1″.
Why Does a Short COG Make Your Car Faster?
How fast your car goes on the first flat part of the track is based on the distance that the heaviest part of the car actually travels before it reaches the curved part of the track. The weight mass of a car with the weight in front will not have traveled as far when it reaches the curved section as the weight mass of the car with the weight in the rear. The farther the weight mass travels the more speed the car picks up on the first section of track. However, if you move the COG too far back the car may become unstable, wobble, pop a wheelie or jump off the track.
If the track you’ll race on is in good condition, very smooth, no rough spots, etc. then go aggressive with a ¾” COG. This works well on most aluminum tracks. If the track is rough, then you should go less aggressive with a 1″ COG. Wooden tracks tend to get rougher with age.
Position the weights in your car so that you have the optimum COG. Tungsten is the best weighting material because of its density. This allows you much more flexibility in controlling your COG.
Remember, the fastest way to check your COG location is with the use of the Center of Gravity Stand.
The Center of Gravity Stand allows you to quickly and easily find your car's COG without rulers or pencils. This is a super simple and very accurate tool for determining COG.