"The '64 Malibu had a fairly soft front spring for autocross applications. The front spring rate was stiffer than stock (Performance Street) but nowhere near the rate needed for autocrossing. The test track was also smooth. A solid 1 1⁄4-inch front bar has a greater rate (stiffness) than a hollow bar given the same OD A hollow bar is lighter (great for racing) but a 11/4-inch hollow bar is about the equivalent to a 11/8-inch solid, (a rate less than the 11/4-inch solid). Since the roll stiffness of the front end on the Malibu was soft, a 11/4-inch solid bar will increase the roll stiffness closer to an autocross application giving you better cornering. However, this is not to say big bars work for everything. On a smooth course, the larger sway bars work, but on rough courses, the larger bars tend the make the car less forgiving. The suspension will not absorb the larger bumps and the car can and often does go into understeer."