Say it with us: “Chevys don’t need 9-inch Fords.” There are other choices and, believe it or not, the venerable Chevy 12-bolt rearend can actually prove a good choice for a rear axle. When originally contrived, Chevrolet engineers penned the 12-bolt with a relatively high pinion gear location—1.50 inches below the axle centerline. In contrast, the Ford 9-inch is 2.25 inches below the axle centerline. This higher pinion location in the 12-bolt results in lower gear lubricant temperature, improved fuel economy, and best of all, more power delivered to the ground.
While it has lost favor with professional drag and oval track racers, the 12-bolt has gained a huge number of followers in other venues. Parts availability for the 12-bolt is simply staggering. Several different companies produce heavy-duty Posi-traction units for the 12-bolt (in several different configurations), numerous spool configurations are readily available, aftermarket axle selection is vast, ring-and-pinion choices are considerable, and small parts (such as bearings, seals, yokes, etc.) are easy to find.
So what’s the catch? Simple. The 12-bolt is becoming scarce. The last one came off the assembly line in 1972, and many of the 12-bolts still available were engineered to fit under fullsize Impalas. These require plenty of work to fit under an ’82-to-present Camaro. Fortunately, there are some excellent options. Let’s take a closer look.