Why has the Ford Nine inch the rear end being the rear axle of choice for street and strip builds for more than seven decades?
The explanation rests in various design elements of the Ford Rear, beginning with the Ford 9-inch gears. The big ring gear with a 9-inch diameter, from which the axle takes its name, and its offset relative to the pinion gear increase the strength of the ring and pinion contact surface area. In addition, the Ford 9-inch employs a removable middle component, commonly known as the Ford 9-inch pumpkin, Ford 9-inch chunk, Ford 9-inch third member, or even a Ford 9-inch pig! This enables quick gear ratio changes to fit changing tracks or modifications to the horsepower and torque specifications of your car. This is difficult to achieve with integral carrier axles, such as the GM 10-bolt and 12-bolt. Using bearing retainers that secure the axle at the flange, as opposed to a C-clip style that secures the axles at the differential, ensures that in the event of axle failure, the axle flange and wheel will remain attached to the vehicle, preventing brake failure and loss of control on the racing surface.
Identify Any Ford 9″Rear End
How Do I Recognize a 9-Inch Ford Rear?
Ford 9-inch rear end identification is simple and requires only a deep socket as a “go/no-go” gauge for the bottom two retaining nuts on the middle section. If the socket fits, the housing is a Ford 8-inch housing. The centerpiece of the 9-inch housing will not let the socket pass, therefore you must use a boxed end wrench to remove the two bottom retaining nuts.
However, the axle flanges and axle lengths are the most crucial features of the rear axle. To order the suitable drum brake backing plates, disc brake conversion kit, or axle bearing retainer, you must specify the flange version. As many 9-inch applications use an offset center, axle length is not always similar from side to side; therefore, you must carefully measure the housing to obtain the right axles.
Identifying Ford 9-Inch Rear End Axle Flange
Taking measurements for your 9-inch axles needs a few fundamental measurements. While there are cut-to-fit axles, you must still check that your measurements fall inside the cut-to-fit area of the splines. Measuring from axle flange to axle flange will yield the overall width of the axle housing. The correct axle length can be determined by measuring from the exterior of the axle flange to the centerline of the pinion gear/nut. Note that most, but not all, applications will typically have one axle that is longer than the other due to an offset center section; hence, it is not sufficient to just measure one side and assume that the other is the same.