• Do they offer a warranty and stand behind their work? (Granted, some high-performance applications cannot be warranted.)
• Where do they get their parts? Directly from the supplier or from a middleman?
• Do they have your parts in stock?
• Can they give you an estimate on cost, and how long it will take to repair?
• Can you see the shop area where the work will be performed?
I don’t mean to scare you or sound paranoid, but we have all had great and bad experiences getting repair work done on our vehicles. OK, enough of the disclaimers.
I have covered the fundamentals of any rear axle. You may not have been aware of what is in a traditional axle and some of the reasons behind the vehicle behavior. Chances are that you have experienced some of the above situations but never really wondered what caused them. The following chapters focus more on the specific details of the different type of axles, differentials, and driveshaft arrangements.
The time has come that your factory axle is in need of repair. You have decided that the 30-year-old housing is worn and it may need to be replaced or upgraded. Now it is time to start scouring friends’ garages and the local scrap yards to find your axle treasure. Before you begin the quest, you need to understand what to look for in your new axle housing.
This is a small sampling of the documents, axle-specific repair manuals, and design notebooks that I used as research and references. There are literally thousands of pages of documents that have been reviewed in an attempt to put together a concise text. Some of these documents are no longer in print or were limited in distribution when they were written. We have even found old research document reports that are from the original engineer’s design notes.
First I will cover some generic types and axle structures. I have spent many hours collecting, reading, and studying old shop manuals, supplier reference documents, SAE papers, and vehicle manufacturer reports and notes. Some of this information is very important because is it becoming more and more difficult to find documentation on axles and differentials that were first introduced more than 40 years ago.
There are two main categories or styles of axle housings available: beam-style axles and independent-carrier-style axles. The main difference is that the beam-axle housing has axle tubes as part of the axle housing; the independent-carrier-style axle is just the axle center section that houses the hypoid gears and differential.
Beam axles use straight axle shafts, and the entire axle housing moves during suspension travel events. The beam axle also reacts to suspension loads through the shocks and springs. When the suspension loads are transferred to the axle housing, it implies that the vehicle loads are also transferred to the housing. The more heavily loaded the vehicle, the more loads the axle must resist. This is more important on light-duty pickup trucks, but does relate to muscle cars, as you may stuff five passengers in the car and go for a zip around the block to show off your new limited-slip differential. The beam axle housing must also react to the braking loads. The brake drums and wheel cylinders (or calipers and rotors) are mounted to the wheel ends of the tubes. Some axle housings even locate the vent fitting in the top of one of the axle tubes.
Here is the renowned Ford 9-inch beam axle housing. This axle stand has some interesting features. On the right tube-support upright, there is a screw thread arrangement to allow us to raise this side during the straightening process. This custom-built axle housing straightening stand has a right-side support that can be raised while heat is applied to the correct spot of the housing. Also, the housing is strapped down to concentrate the tweaking force properly.
Banjo and Salisbury Axles
There are two main types of beam axle housings—banjo and Salisbury—and both of these styles are still in production today. Toyota and Mitsubishi are a couple of the vehicle manufacturers that use banjo axles today while most other manufacturers have switched to Salisbury. All Salisbury beam axles have a cast center section.
There is an interesting history behind the term Salisbury axle. In 1901, the Salisbury Wheel Company was founded in Jamestown, New York. The founder, C.W. Salisbury, patented an automobile wheel. He was a key maker and repaired umbrellas by trade. He paired up with Scott Penfield and E.D. Sherman to start his manufacturing process. Their first customer was the producer of the Thomas Flyer Automobile, E.R. Thomas Company.
The Ford 9-inch banjo-style axle has a cast center section that is painted black and is removed from the front of the axle housing. A series of weld seams joins the multiple pieces, which eventually make up the entire beam portion of the housing.
An assortment of the Ford 9-inch center sections is waiting for a new home in a vehicle. Most reputable shops have a decent inventory of such parts.
The cast center on a typical banjo-style axle housing is shown in light blue. It supports the hypoid gears and the differential. The housing tube portion (yellow) consists of a series of stamped and welded parts with the remaining shafts and hardware being similar to other axles. (Dana Holding Corporation)
In 1905, the Salisbury Wheel Company started producing front axles and, in 1907, began producing rear axles. Around the same time frame, Clarence Spicer started the Spicer Company in Plainfield, New Jersey, not too far from Salisbury, and specialized in universal joints. Charles Dana, an attorney and businessman, invested in Spicer around 1914. In 1919, Spicer Manufacturing Company acquired the Salisbury Axle Company. Spicer Manufacturing is now called Dana Holdings Corporation, but the Salisbury name is still around.
This style of axle became very popular and, with the advent of World War II, many Jeeps were outfitted with this style axle. This axle style was well known in England from the Jeeps during World War II, and the English still refer to this axle as a Salisbury. Just keep in mind that these axles have nothing to do with Salisbury, England. Even today, we still associate the term Salisbury axle with an axle that has a cast center section, rear cover, and pressed-in tubes.
The removable center section from the banjo-style axle looks like this. Notice the adjuster nuts are on either side of the differential, which allow for easier adjustment of the ring gear backlash and bearing preload. The bolts hold the little tabs on the bearing caps in place and prevent the adjuster nuts from loosening up. Also, notice that the pinion bearing feed port has been cut away for easier viewing. (GKN Driveline)