During the spec’ing process, what are the most common mismatches of chassis options and bodies for conventional buses? John Thompson, director of training for American Transportation Corp. in Conway, Ark., responds: A school bus buyer needs to properly match components with the chassis. Some of the most common mismatches in the specification process involve trying to add air options — such as driver’s seats and other air-operated devices — to a hydraulic brake chassis. For example, if you have a hydraulic brake chassis, you need to provide more air sources than if you had bought an air brake chassis. Spec’ing an application of this type will cause additional expenses. In addition, there exists an attitude that heavier spec’d components are better and that’s not always the case. This is particularly apparent in the axle area. Heavier axles and suspensions that are not fully loaded will cause a rough ride and can cause failure of other components. For example, if you have a 23,000-pound axle and suspension and you don’t have the load on that bus to properly compress the springs, you’ll get a rough ride. First, figure out your load and how much you need. If you only need a 21,000-pound axle and suspension for your load, use that because then the springs will be properly compressed and your driver and passengers will end up with a much smoother ride.