Subframe

The principal purposes of using a subframe are, to spread high chassis loads over a wide area of relatively thin sheet metal of a monocoque body shell, and to isolate vibrations and harshness from the rest of the body. For example, in an automobile with its powertrain contained in a subframe, forces generated by the engine and

There are generally three basic forms of the subframe.

1. A simple "axle" type which usually carries the lower control arms and steering rack.
2. A perimeter frame which carries the above components but in addition supports the engine.
3. A perimeter frame which carries the above components but in addition supports the engine, transmission and possibly full suspension. (As used on front wheel drive cars)

Subframes are prone to misalignment, which can cause vibration and alignment issues in the suspension and steering components. Misalignment is caused by space between the chassis-subframe mounting bolts and the mounting hole. There are a number of companies in the automotive aftermarket that offer solutions for the subframe misalignment and movement issue, including TyrolSport of the US and Spoon Sports of Japan.