Axle and Conversion Kits
To transform an OK-running car into a great-running car, changing the rear axle is often the first step. With good round wheels, tight bushings, a straight axle and nice gears, you will really feel the difference. Of course, you can opt to buy the parts individually to get exactly what you need. But in some cases, you would be better off using an Axle Kit from Slot.it. Available in 9 different combinations (sidewinder and inline), they include wheels, bushings, axle, crown or spur gear and needed set screws. From $12 to $22, those kits are a great bargain compared to individual parts.
You can also change the motor configuration of an existing Slot.it car (or any other brand using compatible motor pods) pretty easily by using the Conversion Kits. Available in 5 different combinations (sidewinder and anglewinder), they include the motor pod, the spur gear, the pinion, axle stop (if needed) and all the necessary screws. For $17 or $18, they're also a great buy.