Speed tip?

You may need to remove more or less than a 1/16" depending on how thick of a washer you use, how long your inner hubs are, and how much bend you have in your front axle. The idea is to get the rear wheels centered over the guide rail with the car rolling down the track. If you don't have a track to test with a slow roll you can substitute a strip of wood that's 1/4" thick by 1 5/8" wide by at least two or three feet long.