Читать книгу Ford Differentials - Joseph Palazzolo - Страница 10

It may seem strange to begin by comparing the 8-inch to the 9-inch axle, but there is an important distinction to make since the 8-inch axle is weaker than the 9-inch. Many people are not aware that Ford made a smaller banjo axle and confuse the 8-inch for a 9-inch.

The 8-inch was introduced in 1962 and is found in many lower performance Fairlanes, Mustangs, Falcons, Comets, Cougars, and Pintos, just to name a few of the applications.

There’s an easy way to tell an 8-inch apart from a 9-inch. All of the 8-inch case nuts can be accessed with a socket. In contrast, on the 9-inch, two nuts on the bottom at about the 6 and 7 o’clock positions cannot be accessed with a socket and require a wrench.

Both axles share a common design and are often referred to as banjo style or third-member style. The smaller 8-inch just cannot handle the abuse as its bigger brother can. The 8-inch also was only available with 28-tooth axle shafts. Unless you are building a Pinto or straight six-cylinder vehicle, you want to avoid it.

The smaller 8-inch third member is on the right. Note the two lower bolts at 6 and 7 o’clock have straight access with a socket. The 9-inch third-member bottom fasteners, on the left, can only be accessed with a wrench. This is an easy way to identify the third members, so you’re sure to buy the correct axle.

Both 8- and 9-inch axle housings are made from a series of stampings that are fixtured and welded together. This complex fixturing and welding process, coupled with fuel economy concerns, is what eventually led to their production demise. These axles had a stout 2.25-inch ring gear offset as compared to a 1.5-inch ring gear offset of the later 8.8-inch axle.

The larger offset is better for strength and noise but worse for sliding and efficiency. While the larger offset makes the ring and pinion gears stronger, the additional sliding of the gear teeth creates more heat in the axle. Therefore, these axle assemblies require better quality oil and good underbody airflow to keep the unit cool. With their high-volume production, the two biggest quality problems were leaks from poor welds and poor alignment of the housings. So don’t be surprised that most of these axles leak from the welds. Careful aftermarket shops and their stringent attention to repairing these housings are able to correct many of these issues.