9" Ford rear axles are very popular in drag racing because of their light weight and the ability to change gears easily. The only disadvantage to this design is the tendency to flex and bow under hard acceleration. As the pinion rotates, it tries to climb the ring gear. This force tends to flex the rear housing out of shape. To combat this flex, Competition Engineering has designed the 9" Ford Axle Housing Brace. This two piece brace welds directly to the rear housing, triangulating the main housing with the axle tubes to eliminate any flex. By eliminating the flex, you increase the amount of power going to the tires and improve your ET's as well