What is slip?

When configured for karting, the Off Camber Data software will show “Slip” as one of the channels that can be graphed. In this article, I will briefly explain what the slip graph is and how to use it.

Slip compares the speed of the wheels with the real speed of the kart. When the speed of the wheels is higher than the speed of the kart, that means there is too much throttle, and the tires are spinning. When the speed of the wheels is lower than the speed of the kart, that means the driver pushing the brakes, maybe a little too hard. When slip goes to zero, it means that the tires are locked.

A lot of the time, slip will be mostly constant. When braking, it will dip down. When accelerating, it will tend upwards. This is especially true in the rain, when the driver can get a lot more wheel spin than in the dry.

Slip Graph Illustration

This graph shows RPM, Slip, and Speed together.

Consider the graph above. The interesting part is the right half, after the main straight. Once the driver hits the brakes, RPM jumps down, but speed takes a while to catch up. As a result, the slip graph dips down. You’ll notice that at first, it dips down sharply, but then goes back up a little, staying below its normal level for a while longer. That shape is the hallmark of skillful brake application. Of course, the true way to judge brake application is to use a graph for longitudinal acceleration, which is not shown here.

After the braking maneuver, you see two large spikes. This happens when the kart jumps over the curbs. The rear wheels are getting unloaded, or even leave the ground altogether, while the driver keeps his foot firmly planted on the gas pedal. The wheels start spinning, and you can see that as two sharp spikes in the data.

In the current version of Off Camber Data, this channel only makes sense for karts, and only if the sensors are configured correctly. In particular, to measure the real speed of the kart, it uses the speed sensor on the front wheels. To estimate the speed of the tires, it uses the RPM sensor on the engine. This method only works if the speed sensor is on the front wheels, not on the rear wheels. Also, both brakes and engine have to act only on the rear wheels. Finally, it does not work on shifter karts.

With time, we will overcome these limitations. Please leave a comment or email us if it is important to you that we fix this sooner rather than later. We are always available at feedback@offcamberdata.com.