Some cars have variable-ratio steering, which uses a rack-and-pinion gear set that has a different tooth pitch (number of teeth per inch) in the center than it has on the outside.

In this paper, the meshing theory of rack and pinion steering gear with variable ratio is studied systematically.

LFI is a manufactory specialized in producing and selling CV joint boots, steering rack pinion boots and shock absorber boots, applicable to Japanese, European, Korean and American cars.