How to Identify a Rear End

Since roughly fifty years ago, there has been an ongoing argument among car aficionados. It is a Ford vs Chevrolet dispute. Well, almost. It has been debated whether the Ford 9-Inch or the Chevrolet 12 Bolt rear axle is superior.

How to Identify a Rear End

Ford Nine-Inch

The 9-Inch rear-end, first mass-produced by Ford Motor Company in 1957, has become a standard among gearheads of all ages. The housing’s capacity to accommodate nearly any gear ratio between 2.47:1 and 6.14:1 makes it a popular option for those of us who intend to race our beasts on the track and then drive them home. This is best served by the removable third member, which facilitates the replacement of the ring and pinion gears. Other advantages of the Ford 9″ include the fact that it is larger than the Chevrolet 12-bolt. Chevrolet’s 12-bolt ring gear has a diameter of 8.875 inches, compared to Ford’s ring gear’s 9-inch diameter. Located 2.25 inches below the centerline of the ring gear, the Ford 9″ also features a larger tooth contact patch. Before adding the brakes, the average Ford 9-inch weighs approximately 175 pounds.

Chevrolet 12-Bolt

After its introduction a few years later in 1965, the Chevy 12-bolt was predominantly used in Chevrolet passenger vehicles from 1965 to 1972. The GM design is marginally more efficient than the Ford 9-inch design. Due to decreased friction, the Chevy 12-bolt’s pinion sits 1.50 inches below the ring gear’s centerline, resulting in minor horsepower savings. The normal Chevy 12-bolt weights around 185 pounds when equipped with drum brakes, however drum brakes are no longer often used on hot rods. When compared to the Ford 9-Inch, the Chevrolet offers several advantages. The old cast-iron caps of the Ford 9-Inch are an inherent vulnerability, and after changing to a modular system, the retainer and pinion bearings will also need to be upgraded to prevent a domino effect failure. In comparison, the Chevy 12-bolt’s normal case configuration is nodular.

The Conclusion:

You have the final say over which rear end will be used for your project. Consider your ambitions; do you want a dedicated strip car, or do you want to participate in poker runs with your friends? One final piece of advice, and then we will let you return to your construction; remember that it is your construction, not someone else’s.