How To Identify 31 Spline Ford Axles

Before you commence on the rebuild and starting time scouring local flake yards and online websites, it will exist helpful to empathize what to look for and what to avert in these axles.

Beginning, you need to empathize some fundamentals of the Ford axles to help guide your quest. I have spent countless hours over the years collecting, reading, and studying erstwhile shop manuals, supplier reference documents, SAE papers, and even vehicle manufacturer reports and notes. Some of this data is very important equally it is becoming more and more difficult to find documentation on axles and differentials that were congenital more than 40 years ago. I have as well spent many hours in fleck yards and visiting and interviewing the experts in this field along with years of building numerous axles myself. In this affiliate I share a summary of decades of piece of work on these axles.

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As part of my research, I went to renowned Currie Enterprises and gathered one of merely nigh every different 9-inch axle variant. I put together a whole collection of housings and third members. This is a sampling of some of them. Here is a quick visual summary: The 1957 housings exercise not have dimples on them and have an oil drain plug. The 1958s and 1959s accept ii dimples on either side of the housing and some have drain plugs. The 1960s to 1967s still retain the dimples but also have an oil level plug in the back comprehend.

The Ford eight.eight-inch axle has a cast center section and the internal components are installed from the rear. There is typically a stamped steel cover that must exist removed to proceeds access to the internals.

This chart serves as a general guideline for axle fl ange-to-fl ange width based on different models and production years. I have included the narrow viii-inch axles for reference. The narrowest production 9-inch axle is 56.375 inches. If measuring the drum-to-drum altitude, add together .200-inch to these values.

An assortment of Ford 9-inch axle stampings is welded together to create the housing. The cast-iron third member is installed from the front end of the housing. The third fellow member supports all of the gears and bearings, which allows for easier gear ratio swaps if you lot have multiple third members.

 

There is a very key difference between Ford's eight.viii- and 9-inch axles. I reference these axles based on the ring gear nominal outside diameter in inches. The central departure between these axles is how the gears are supported and which stop of the axle housing (front or back) that they are assembled from.

8-Inch

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

The eight-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'southward an piece of cake manner to tell an 8-inch apart from a 9-inch. All of the 8-inch case basics can be accessed with a socket. In contrast, on the 9-inch, two nuts on the bottom at about the vi and 7 o'clock positions cannot exist accessed with a socket and require a wrench.

Both axles share a common blueprint and are ofttimes referred to as banjo style or third-member manner. The smaller 8-inch just cannot handle the corruption as its bigger brother can. The 8-inch besides was only available with 28-molar axle shafts. Unless you are building a Pinto or straight six-cylinder vehicle, you lot want to avert it.

The smaller 8-inch third member is on the correct. Note the two lower bolts at half-dozen and seven o'clock take straight admission with a socket. The 9-inch 3rd-member bottom fasteners, on the left, tin can only be accessed with a wrench. This is an easy mode to identify the tertiary members, so you're certain to buy the correct axle.

 

Both 8- and ix-inch axle housings are made from a series of stampings that are fixtured and welded together. This complex fixturing and welding procedure, coupled with fuel economy concerns, is what somewhen led to their production demise. These axles had a stout 2.25-inch ring gear offset as compared to a i.five-inch ring gear showtime of the after 8.viii-inch beam.

The larger offset is better for force and noise but worse for sliding and efficiency. While the larger starting time makes the band and pinion gears stronger, the boosted sliding of the gear teeth creates more than estrus in the axle. Therefore, these axle assemblies require better quality oil and proficient underbody airflow to keep the unit of measurement cool. With their high-volume production, the two biggest quality issues 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 attending to repairing these housings are able to correct many of these issues.

9-Inch

The Ford 9-inch has a reputation equally a durable beam that tin can transmit enormous torque, and this is rightfully deserved. Some even consider these axles to be bulletproof. This is by far the nigh common axle used by restorers, hot rodders, customizers, and racers. Information technology has enjoyed a long production history with many variants. There is a huge aftermarket back up for this beam pattern. Many companies, such every bit Currie Enterprises, Marking Williams Enterprises, Moser Engineering, and Foreign Engineering science, reproduce this design today. It is still used in NASCAR racing as well.

Because of the long production history of this axle, many variants are bachelor. Almost of the time, the differences are in shock and jump mounting brackets and, of course, brake hardware. It is a banjo-mode axle as is the viii-inch. It was in product on many Ford cars and trucks, commencement appearing in 1957 and finally replaced by the Salisbury-style 8.eight-inch axle in 1986, saving most 50 pounds and boasting increased efficiency.

 

Here is an example of a weld repair on a factory original housing. It was required to repair a leaking weld. The repair process requires the axle to exist disassembled and thoroughly cleaned. The leaking weld area is and so footing downwards and a MIG or TIG welder is used for the repair. This is a relatively common issue on these housings.

The straddle-mounted pinion has a roller bearing in the gear case, which provides additional support for the pinion under heavy loads. This begetting and the casting structure surrounding it need to be carefully inspected as this is a common area for cracks.

This pinion has the tapered bearings and collapsible spacer in place. The bearing cups are in the pinion cartridge and the third bearing trunnion roller bearing is located in the gear case. This pinion shows excessive wear on the trunnion surface and should not exist re-used.

 

Pinion Showtime

The 9-inch's very large pinion offset of 2.25 inches requires the pinion to be straddle mounted, which refers to the fact the pinion head has bearings that straddle it on either side. There is a machined roller bearing race on the pinion head portion that points at the differential opposite the tapered bearing races. This additional bearing and, more chiefly, the necessary casting back up structure is what drives the larger hypoid offset. The additional straddle mount pocket begetting provides boosted back up to the pinion head during high-torque events. This bearing is one of the reasons that the 9-inch has the reputation for beingness bulletproof.

In that location are iii bearings on the pinion shaft: the two traditional tapered roller bearings for the head and tail bearings with a third cylindrical roller bearing on the contrary end of the pinion head. In gild to allow for the boosted straddle mounted bearing and casting support structure, the hypoid outset needs to be large enough to articulate the differential case. Hypoid beginning is the distance between the centerline of the pinion and the centerline of the band gear. This is 2.25 inches for the Ford 9-inch and 1.five inches for the 8.8-inch axle.

Identification Tag

People have been climbing around scrap yards for years to observe the all-time examples of the ix-inch axle. If you lot are fortunate enough to find an axle with the identification tag all the same attached, it volition assist solve part of the mystery of what awarding the axle came from and what might still be inside.

The axle identification tag is located at nearly the 3 o'clock position nether the third-member mounting nut when you are looking straight at the front of the axle. These tags are typically quite beat out up, twisted, and rusted over the years. These tags were not that informativeon the early units, so from 1957 to 1962 the tag just referenced axle ratio. In 1963, Ford included more information.

This is a typical beam tag that has been removed from the third member. The code, 4L11, tells united states that it is a 4.11:ane ratio with a limited-skid or Traction-Lok differential. It too has a nine-inch ring gear.

 

The axle tag typically has ii lines of numbers and letters stamped on it. The format has changed over the years only mostly follow this sequence:. The superlative line typically starts with a three-digit axle model code (or the prefix of the office number), followed by a dash, then the suffix. The axle model codes are interchangeable, typically the suffixes are dissimilar for a revision change merely the axle is still interchangeable with ane having the previous suffix. There may be a second dash and more numbers and letters on the top row if in that location are specifics that are unique for interchange information. Typically with simply this information, you tin cross reference what yous need to know about the axle. The final set of digits on the tiptop row on the right side is the date code.

The bottom line begins with the ratio being the offset fix of numbers. If an L is included, it was equipped with a limited-sideslip differential or Traction- Lok. The centre number is the ring gear bore in inches, typically an eight or 9. The last set of numbers is the vehicle plant lawmaking.

If the axle tag is missing, as most are, you need to remove the tertiary member in club to know what ratio y'all have and if it has a limited-sideslip or not.

This custom axle tag was obviously hand cutting every bit evidenced by the abrupt tin-snipped-looking ends and includes DSO, for Dealer Special Order. Notice that the appointment code is C9UA with the band gear size of viii.7. This was an eight.75- inch ring gear in a ix-inch housing. These were used sporadically until virtually 1969. You tin can install a true 9-inch gear in these housings also.

 

Don't be surprised if the tag you have does not exactly match this. There are also unique domestic special-option tags, which don't follow the format.

Date Code

The date lawmaking is stamped on the tag. The first number is the last digit of the model yr of the decade, the adjacent digit is a letter and represents the calendar month (A is for January, B is for Feb, and so on), and the final two digits stand for the day of the month. This format is also applicable to casting appointment codes.

The date code on this beam tag is 7AC, and it corresponds to the 7th year, 1st calendar month (January), and 3rd day. The WFE-V2 helps usa fi nd the decade of the 1970s. This beam tag belongs to a 1977 F-150.

A metal axle tag is typically located on the driver-side front of the third member. Information technology is underneath one of the basics that holds the third fellow member in place. In most cases, the tag has been lost. On this particular tertiary member, the original copper washers that were nether the factory fasteners have been discarded as well.

 

Some tags reference the week of the month instead of the exact day and just use a letter (A to E) for commencement through the fifth week of the month.

Case Type

You are looking for a nodular iron case, with its telltale "North" cast into the front or inside wall. These 3rd members are the strongest of the production cases and the most desired. Aftermarket vendors are actually re-casting these cases in very strong nodular iron, so by and large information technology is easiest just to purchase a new instance.

Simply if you lot're looking for an original, they can be spotted quite readily even without an axle identifycation tag. The Northward cases had ii vertical ribs, 3 horizontal ribs, and a machined-in fill plug. There are four versions of the nodular iron tertiary members that were produced from the factory. These offset became available on the 1964 Galaxies with the 427-ci engine and were found on many higher horsepower cars and trucks.

Of the iv versions of the Due north example, three accept an actual "N" cast into it correct above the pinion cartridge.

The fourth version did not take the "N" in the casting on the exterior simply however retained the rib structure. In guild to verify a nodular unit, yous need to look on the inside of the casting. These have a C4AW-4025-B casting part number next to the adjuster nut.

Of course, if your upkeep allows, yous can buy an aftermarket iron example that is stronger than any factory example. If you are looking for an North example or remember that you lot have found one of these desirable axles, make sure to examine information technology closely. The WAR, WAA, and WAB cases have the same ribbing as the North case, but are missing the ever of import "N" characteristic.

This chart references the connection between the month codes and the actual month. The letters I and O are skipped to avert confusion with the numbers one and zero.

 

Any of the W-series cases do have a fill plug machined in them. Both standard and W-series cases are made out of gray cast iron. Only the N-series cases are made out of the stronger, more desirable, nodular atomic number 26. While the iron is molten, magnesium is added to increment the shear forcefulness of the alloy. The magnesium addition causes the grain structure to change from flakes to nodules and thus the proper noun "nodular" fe. The Northward cases typically came with the larger Daytona-fashion pinion support bearing, and 31-spline axle shafts.

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This Tech Tip is From the Total Book, FORD DIFFERENTIALS: HOW TO REBUILD THE 8.8 AND 9 INCH. For a comprehensive guide on this entire subject you can visit this link:

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SHARE THIS ARTICLE: Please feel free to share this post on Facebook / Twitter / Google+ or whatever automotive Forums or blogs yous read. You lot can use the social sharing buttons to the left, or copy and paste the website link: https://www.diyford.com/ford-beam-history-identification-ford-differentials/

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Pinion Cartridge

There are even dissimilar pinion cartridges that have been available from the various production years and models for this axle. The Daytona- style cartridge allows for a larger pinion head begetting when compared to the standard pinion cartridge. This is a great upgrade component to employ for high-power applications or if y'all are replacing your cartridge.

Housing

Like well-nigh Ford axles, the 9-inch has a single hypoid ring gear mounting distance, then, unlike the Dana and GM axles that require unique differential carriers based on ratio, a single differential carrier works with all of the Ford ratios. Also, since this axle is used in so many circle-track race cars, the 9-inch enjoys an unparalleled availability of different gear ratios in the aftermarket.

This example looked like a nodular unit from the front regarding rib structure simply did non have the "Due north" on it. When yous look on the inside, yous see WAB- 4025A. This is not a nodular unit.

The desirable North-way, nodular-fe gear cases are available in four different versions. There are iii versions with external Ns cast in; note the more curved way on the top right. The unit on the top left seems to exist nodular iron merely requires a little more investigation to verify.

 

This is when making a few phone calls to reputable axle builders tin be helpful. There are quite a few companies making Ford 9-inch housings to fi t merely about any muscle auto out there, including non- Ford vehicles. (See Affiliate 8 for how to install a 9-inch in a classic 1957 Chevy Bel Air as a operation upgrade.)

The axle housings themselves had many different variations over time likewise. These variations include different-size drum brakes, disc brakes, and wheel hub arrangements.

The aftermarket Daytona-mode pinion cartridge accommodates the larger and stronger pinion head bearing. This detail pinion cartridge is well reinforced and much stronger than the stock product cartridge.

Here are the internal sides of the same three units. Now you can see the C4AW-4025-B part number on the lower left unit, which verifies it as a nodular unit.

 

Since these housings were a series of stamped-steel pieces all welded together, there were many different overall lengths, tubes sections, mounting brackets, and fifty-fifty general constructions over the years (see Chapter five).

viii.8-Inch

The Ford 8.viii-inch is very similar to the Full general Motors (GM) 87⁄8-inch, 12-bolt axle. Some differential experts tell you that the Blue Oval engineers copied the 12-commodities design when they came upwards with the viii.8-inch axle. While the 8.eight is like to the 12-bolt, it isn't identical. Interestingly, the Ford beam uses the exact same size of tapered roller bearings as the GM 12-bolt. The Ford version uses larger beam shafts and different lube flow strategy. These axles did have metal axle tags similar to the 9-inch axles only they were slowly phased out as vehicle programs were updated. There are several reasons for this.

Cost and complication are ii. These tags provided data for the service technicians but wasn't that important for the vehicle associates plants. The 3rd reason was basic wellness and safety concerns for the associates technicians and other employees who handled the axles in the manufacturing and assembly plants. In that location were many instances of cuts and scratches from the sparse steel tags sticking up on the axles.

This is an case of the brakes that fi t the small bike end bearing for a ten 10 2-inch-broad drum brake on the left and a 10 x 1¾-inch on the right.

Here is an instance of xi x two¼-inch drums brakes with the small bearing size on the left and the big Torino fashion on the right.

The large bearing size was bachelor with fi ve different restriction drum widths. Four of the 11 inch-diameter versions are pictured: 1¾ inches (top left), ii¼ inches (pinnacle right), 2½ inches (bottom left), and iii inches (lesser correct). A 2-inch version is not shown.

Forth with the many different restriction and wheel end varieties, many different styles of axle shaft ends were manufactured. Some have only one admission hole for the bankroll plate bolts, while others have three. Almost have the two driving holes for the manufacturing process while one has a more than square looking bulldoze cease. None of which changes the strength of the axle shaft. There are fifty-fifty different pulsate brake registers.

The Lincoln Continental way of disc brakes use 11½-inch rotors. In the 1980s and 1990s, the Lincoln Versailles brakes and complete axles were highly sought afterward because information technology was the only way to get a ix-inch axle with discs in a 58-inchwide axle bundle. At this width, many were used in street rod applications without modifi cation. With and then many better performing aftermarket options today, there is no reason to use these marginal brakes.

Some axle shafts can be shortened and a new spline machined in place. The 28-tooth axle shafts are typically tapered and cannot be shortened. Most 1972 and before 31-tooth spline shafts can exist shortened and 1973 and later versions typically cannot exist resplined. Here is a movie of the milling machine cut new spline teeth afterwards the axle has been cutting to length.

This is an case of the only Ford nine-inch version that utilized jumpsuit tubes. Note the weld on the meridian of the beam centre department along with the oval-shaped dimples on the rear section. The tubes do not have any welds, and yous only run into the witness marks of the parting line for the dies on the tubes. This was offered on the 1960 F-100 truck.

Besides the styling of the Ford Edsel, even the axle shafts were very unusual. These shafts had a longer brake spacing offset and a unique restriction drum register diameter of ii.870 inches, which was uncommon for the time. (It was later used for selection-ups and Broncos.) These axles even have a unique bolt pattern of five on 5 inches. I guess this helps add to the splendor of the vehicle.

The Mustang Shelby GT housing is an easy ane to spot, admitting rare, because it has extreme tapering of the axle tubes at the ends. There was a desire to take the stronger, larger tubes near the center of the beam but nevertheless retain the narrower tube ends for the cycle ends and the unique Shelby suspension brackets.

From my piles of rare parts, here is an independent cast-atomic number 26 8.viii-inch carrier axle. Note the ring diameter cast into the housing above the pinion.

The Lincoln LS and Jaguar Southward-blazon were equipped with an 8-inch, castaluminum, independent- style carrier. Detect the eight.0-inch ring gear diameter cast into the rear embrace below the fill plug. Too notice the function number and metal axle tag. The bar code is present on this unit too, although later axles just carry the bar code and the metallic tag is no longer required.

Ironically, 8.0-inch independent carriers were made in bandage iron. Here is an example of such a unit of measurement.

The Ford Explorer uses an independentstyle Carrier fabricated out of cast aluminum. The ring gear speed sensor is shown in the upper correct-mitt portion of the photo. This sensor is for the anti-lock brake system.

 

The tags were replaced with adhesive labels that are placed effectually the axle tube about the brake and wheel end. These labels take a specific code that is similar to the axle code on the 9-inch axles.

The Ford 8.8-inch beam has the same band gear mounting distance (run across Chapter 7) for all ratios, just like the 9-inch. So again, dissimilar the GM and Dana axles that require a unique differential with different ratios, the Ford 8.8-inch differential is common beyond all of the ring-and-pinion ratios. In that location is a ton of aftermarket support for this beam (run into Chapters 3 and 4 for more details).

The 8.8 is a traditional semi-fl oat Salisbury axle with C-washers for beam retentiveness. Many people prefer to only call it the Ford nine-inch-way bike finish. But to be right, it is a 3/4 fl oat. There are viii.five-inch gears installed in these housings for lowerpower vehicle applications. The typical three inch-diameter tubes can be a bit flimsy in higher-ability applications.

The 8.five- and eight.8-inch gears take even found themselves in the independent-carrier-fashion axles. The Ford Mustang and Thunderbird used this style for a few model years. There were likewise viii-inch ring gear contained carriers in production.

Written by Joe Palazzolo and Republished with Permission of CarTech Inc

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