How to Troubleshoot Slot Cars

Replace the batteries. Most slot car sets take four D-cell batteries, installed in a central generator that mounts onto the track. As soon as batteries begin to weaken, the cars will lose speed and the controllers will become sluggish.

Disconnect the controllers from the generator and reconnect, making sure that the "+" and "-" wires of the controller are connected to the correct terminals. A reversed connection can cause the cars to run backwards around the track, as can improperly inserted batteries.

Remove the cars from the track and check the copper contact braids on the car's underside to ensure they are not frayed or bent back. Both braids must extend all the way down to the silver connector strip on the track or the cars will not run. Brush the braids with a brass wire brush if they have become frayed.

Sand the tires of your slot cars down if the cars leave the track too often. While the aim of slot car racing is to regulate speed to keep the cars on the track, cars with tires that have a roughened surface will grip the track more strongly, increasing player control.

Push the car's bottom plate up into the frame to ensure the car and motor fit securely together without rattling. If the car's parts fit loosely, remove the bottom plate and glue the motor into place with a dab of hot glue, then replace the bottom plate and dab glue onto the connection tabs. Keep hot glue away from the motor's internal workings and the wheel axles as this can slow the cars down.

Turn the car upside down and push both rear wheels down into the car's frame to click them back into place if the motor runs without spinning the wheels. Perform the same action on the front wheels if the rear wheels spin on the track without the car moving forward.