After the basic design is determined, you will need to get cracking on axle placement. It is one of the most crucial parts to install, so getting it right the first time is pretty important.
The axles need to be positioned with perfect alignment to allow the car to roll down the track in as straight a line as possible. If they are not straight, the wheels will battle each other and slow the car down. In addition, the axles need to be far enough into the car, but yet leave enough space between the body of the car and the wheel to allow free spinning motion.
Don’t trust the precut grooves in the block because they may not be square. Before the shaping and carving begins, draw a line for the axles using a square and a pencil to make sure they are congruent. Drill out only when you know your axles will be square. It’s much easier to do when it’s still in block form, than if you try to drill out after your car has its intended shape.
Several things should be checked to see why you’re not getting the performance you want.
Don’t forget to lubricate your axles with graphite. Most often your competition will allow you to lubricate directly before you race, but make sure you have done this ahead of time as well. Give each wheel a spin and apply a little bit of graphite at a time until you achieve your maximum spin rate. Graphite is messy, so do it over a workspace that you aren’t worried about.