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Tech Tips 3

How to Identify some typical Ford Centers

 Let's start with the 9"

First off, the 9” is a removable carrier type rear end, it shares this design in common with it’s baby brother the 8”, while the 6 ¾”, 7 ¼’, 7.7” , 8.8” and Dana rears also used in Fords are integral carrier types. Both GM and Mopar also had earlier removable carrier type rear ends, they are no where near abundant as the Ford. Removable carrier means these are front loading differentials, they have no cover / inspection plate on backside-the 8.8's etc are considered rear loaders. When a gear ratio change is desired, a entire carrier assembly (previously assembled) can quickly be installed by simply pulling the axles and drive shafts, then undoing the ten center retaining nuts.

Quick ways to identify a 9” visually:
From rear of car look for a large center hump in middle of backside center section (post 66 models), in general a round appearance, it is a 9”.See photo above.
From front side look at the bottom two center retaining nuts, if a socket cannot access them to remove, only a wrench, then it is a 9” See photo below.
I have heard various stories as to the reliability of the WAR marked cases, some say avoid them like the plague, others say this is false. Here is what I understand, while having the extra ribbing like the later N case, they do not have the nodular iron content and are prone to cracking at the bearing support. They seem to have been used on the 57 to 60 Fords from casting dates I have seen.
The C7AW-E case seems to have been the standard case in use for quite sometime, have found them with date codes up to 1981.Other standard cases encountered: C1AW-4025-C,C4AW-4025-A
Some standard cases are also machined to take the larger 3.063”(the C7AW-G mainly) side bearings, most cases however (including N cases) will take the 2.892” side bearings. Aftermarket spools and cases are available that accommodate even larger bearings-3.250" and 3.812", but Ford used just the two sizes from what I have seen. The carrier I have seen with the 3.063" larger side bearings is the C7AW-G marked single ribbed case, it came from a late 60's Galaxie.Have heard that the case C4AW-4025-C is also a large bearing single ribbed case.
THE N Case vs WAR Case
"Standard or WAR cases, were cast in gray cast iron which has a grain structure that does not have the best shear strength characteristics. The N stands for nodular iron, which is made by adding magnesium to molten iron. What this does is change the grain structure from flakes to nodules - much stronger and less likely to fail under shear load." - contributed by Paul Bartus The case of course most desirable is the N case, first used on the 427 Galaxies around 64-65 I believe. They are most often found behind the later 428CJ and 429CJ cars. From what I have seen don't expect to find them in 390 or 289 Hipo cars. The N cases went with 31 spline centers and are for rugged duty. And believe it or not, they were also used in some FE equipped Ford 1/2 ton 4X4 pickups!
Here's a quick tip someone sent me for spotting an N case while installed in a housing, look to the area just to the right of the carrier fill plug on side of case, on an "N" case an only an "N" case this area will be filled in-flat cast metal. On the "WAR", "WAB" and standard cases there will always be a cast in recession that forms a pocket. The 9 3/8" also has this area filled in-but it has the bent down horizontal rib end. Compare the various photos on page and you should see what I am talking about.
Here is the early N case, the C4AW-B casting, which can either have the N or not. Some N cases will also have the bearing caps marked with an "N", some do not.
Have also viewed a N case marked with an "N" with a C2AW-4025-A casting number,it was used in conjunction with a C5AW-4668-C Daytona pinion support. Case was double ribbed, this casting number is not listed in my books or references, will have to do further research regarding this one.

Pinion Supports

Standard Supports Other standard pinion supports encountered: WAT B2(on a WAR case),C0AW-A,C5AW-4668-A,C6AW-4668-A,C7AW-C(guarded), D2AW-A (guarded) and a D2SW-4668-C(marked with the 4668).The D2SW-C seems to be the most common encountered through 1979 on the C7AW-E cases I have viewed.
Daytona pinion supports are found in conjunction with N cases, they have the same size outer bearing as the standards supports, but the inner bearing is much larger, and the inner webbing much stronger. Visually on the outside look for a flat surface with no raised areas around the mounting holes (this is true for the non-guarded/hooded supports only). Photo below shows a standard support on left and a D2OW-4668-C Daytona support on right with their respective bearings. The D2OW-4668-C is the only Daytona support that I have seen to have the guard/hood cast in. Inner bearing number for Daytona support (D2OW-C) is HM89443, with a HM89410 race. Aftermarket supports of equal or greater strength (larger bearing sizes) are available. Earlier Ford daytona pinion supports: C5AW-4668-C, D10W-4668-A . Photo courtesy of Shawn Reim

A 9 1/2" ???
Here is something else you may run across, a 9 3/8" ring gear housing(sometimes called a 9 1/2" Ford carrier),I don't know much about them, but looking in the book they appear to have come in the larger Lincoln and Mercury vehicles. Note casting number C8AW-4668-B on pinion support and the double ribs(spaced further apart) with the end bent down on one. From what I understand most parts from these rears do not interchange with the 9 inch carriers I have heard they can be installed in a 9" housing if the housing is notched for the wider gear and the gasket for the 9 3/8" is used (bolt pattern is supposedly the same).I have started to see a few of these in some Ford pickup applications, mainly 4X4 with a trac loc option and FE motors. The truck applications seem to have some better ratios than the passenger car applications. All the applications of the 9 3/8 I have seen have been 31 spline.


Here is some 8" info:
The casting number should be C2OW-4025-F, NOT C2DW listed for the case. Another later 8" pinion support with guard built in that I have seen had casting number C6OW (the 6 however may have been a 5-this support came out of a 65-66 mustang center).
Later improved carrier for the 8" found in 67 and up
Note the presence of fill plug, and that the casting number is moved to the outside of case, while other previous 8 and 9 inch carriers it has always been on the inside. The number here is the familiar C7OW-4025-A. Housing Types and SizesVisually Spotting the 9" and 8" Axle Housings 
 Shown above is the typical 1967 and up 9" (lower) and pre-1967 8" housing (upper).Note no fill plug on back of the 67 and up housing, this is true for the 67 and up 8 inch housings too. Earlier housings, like the 65-66 Mustang 8" pictured have the fill plug in the back, this is true for the earlier 9" as well.
One of the ways many people spot a 9" rear end in the car is by looking for the hump in the center of housing, this is not always the best way, as 9" housings made prior to sometime in 1966 do not have the this large center protrusion. The one shown above is out of a 63 Galaxie, note its roundish appearance, two dimples and fill plug in housing back. Here is the housing style familiar to most, note the large center protrusion or simply the "hump" in the middle. Housing also has the two dimples, but note lack of fill plug. This housing is out of an early Bronco.
The little brother to the 9" housing is the 8" housing, note its more oval appearance when compared to the above two 9" housings. This one is out of a 65-66 Mustang, note the two dimples and fill plug.  Housings and Bearings, etc.

This is a new section with some recently obtained specific information I have gathered on the types of bearings and housings used by Ford. For the nine inch there are two bearing sizes used for housing ends, the smaller eight inch used just one. However, for the nine inch (as assembled by Ford)there are 3 different bearings- one small and two large. The two large are the same size ( I.D. / O.D specs), but different types of bearings- one is the traditional sealed ball bearing, while the other is the oil bathed roller bearing and race type. The eight inch and most nine inch housings used the small bearing- including the 31 spline CJ cars, Mustang Hi-performance etc.. This bearing was of the sealed ball bearing type, # RW207CCRA (specs: 1.378" I.D., 2.8246" O.D. by 0.8449" width). Early Galaxies and Broncos and some mid 70's Torinos used the large type sealed ball bearing, which meant they had a large tube housing end, bearing # 88128-RA (specs: 1.5312" I.D., 3.1496" O.D. by width). The second type of large bearing (roller type) was used in later pickups and larger Ford cars, bearing # A20 (specs. 1.530" I.D., 3.1530" O.D.), the seal was on outside of bearing. Because of the two different size bearings used in the 9 inch, there are also two (actually three) different backing plate mounting patterns as well. The standard small bearing has an approximately 3 1/2" (horizontal)by 2" (vertical) pattern with 3/8 inch mounting hole diameter, while the large bearing is 3 1/2" by 2 3/8" respectively with 1/2 inch hole size. Some of the mid 70's Torinos used a slightly different plate with a spacing of 3 9/16" by 2" respectively with 3/8" hole size. Good news for restorers and rodders out there is that there are adaptor bearings available to ease the swapping of axle shafts and housings that would have originally been potential problems. There are bearings made to swap the larger 31 spline shafts that may have been shortened into small bearing housings (spces- 1.531" I.D. by 2.834" O.D.)-it is available from aftermarket suppliers. I think there is also a bearing that will do the swap the opposite- swap typically small bearing shafts into a large bearing housing, the info I have found is that the BCA 511004 will do this, haven't tried it myself yet, but is has the correct 1.378" I.D. by 3.1496" O.D. .
Another area of concern when swapping axle housings into earlier Mustangs (65-66 models especially)is the diameter of the outer axle tube. Note the taper on this 8" 65-66 Mustang housing, a smaller U bolt and lower shock plate were used originally with these cars The HIPO 289 cars were the only 65-66 Mustangs to receive factory 9" axles, the tubes are tapered as well at the end to utilize the same lower shock plate as the regular 65-66 Mustangs.
Notice this axle tube has no taper at end, as is typical for most housings. A typical early Mustang swap is a later Granada housing, were the non-tapered tube can become an installation problem at times.

Measuring Housings

A note on measurement of housings, a couple of things need to be considered. First overall width, second spring perch location (or modification for coil spring use).When I talk about overall width measurement here on this page, I am referring to the measurement from the inside housing flange side to side. For example, the typical early 65-66 housing is about 52" (actually more like 52 1/4"-I am just rounding for convenience here). You can also measure axle flange to axle flange (this is the flat surface brake drum rest on when installed on axle shaft), generally this adds about 5 inches to the housing flange to flange measurement- i.e. the 65/66 Mustang measurement would be about 57 inches if measured this way. Spring perches are measured by their center to center distance from each other, and by the distance from the housing flange end. For example, all 65 to 73 Mustang spring perches are located slightly over 43 inches apart - physically you could bolt a 73 Mustang housing which is over 56 inches wide into a 65 Mustang body with a normal 52" wide housing because the spring perches are in same location. The wheel would however obviously extend well outside the fender. What changed was the distance from the spring perch to the outer housing flange- it grew two inches per side in this case, 4 inches overall.  Housing Ends/Brake Backing Plates  

Shown above are a large bearing housing (to left) and a small bearing (right), the bolt spacing is different between the two as is the center hole opening, thus they utilize different backing plates for the brakes. Most small to medium size cars utilized 10" rear brakes, in 1 3/4", 2" or 2 1/2" widths. The larger cars and many trucks utilized 11" brakes, typically 2 1/4" width. Finding the small housing 11" backing plates can be a little more difficult than some of the other applications. Another popular alternative is to upgrade to 10 X 2.5" . Photo below shows the two different size backing plate mounting studs- large and small used with respective size bearing housings. I  Axle Shafts

Shown above is a 31 spline shaft end in a 69 Cyclone CJ Ford used either 28 spline or 31 spline axle shafts with the nine inch, the eight inch came only in 28 spline, as did the majority of nine inch car applications. For the most part eight inch and nine inch car axle shafts will interchange between housings of the same width, spline count and bearing size (ie. 8" 67 Mustang 28 spline axle shafts will work in 9" 67 Mustang housing, etc.).A method to identify 28 spline axle shafts can be by looking at the center brake hub area, a rectangular slot in the center will indicate 28 spline axles.The 31 spline axle shafts will have a different appearance, with one small center chamfer and two outer holes in the center hub, however, 28 spline shafts can also appear like this to, so it does not always indicate 31 spline shafts (see photo below). Early axle shafts of the 28 spline variety cannot be shortened, due to either a reduced diameter between spline end and bearing end (early Mustangs, Fairlanes, Falcons etc.), or because of a tapered shaft which doesn't allow for re-splining (early full size).It appears starting around 1967 the 28 spline shafts became more solid and the shaft diameter increased along the entire length, so shortening is possible and they can be resplined to their original 28 count. Most 31 spline shafts can be shortened and resplined with no problems.
(above)Small bearing shaft on left, large bearing shaft on right

Note the early axle shaft with tapered middle section, these cannot be shortened or resplined

Rear Axle Tags Rear axle tags if present on your housing can aid in identifying what is behind your center for gears, splines etc. Ford has changed the tag over the years, but generally the application number-which begins with the W on line one and in format of Wxx-x etc. (these can be referenced in id manuals to identify original car/truck type installed in), the gear ratio and date code are given as well- with the gear ratio generally starting the second line followed by the date code (most of the time). If the unit is a locking type, the gear ratio will have an "L" after the first digit and before the final two digits (else there will be a blank space for an open). The final info given on later tags is the housing type installed into (which can be used to identify car/truck line installed in as well) - ie. an 8 inch Mustang, 9 inch Mustang, 8 inch Fairlane etc., housings can be slightly different even for similar or the same models. For instance, an 8 inch Mustang housing (67-70) is "930" while an 8 inch Cougar for the same years is a "931".The slight difference probably due to the different style lower spring plate and larger center pin hole used on the Cougar housings with the rubber pads - similar to the Fairlane mounting set up, while the Mustang housing has a smaller center pin hole in spring perch. This final axle Id number can also be found on a cars build sheet (67 on up), just look under "Axle" section, it will appear slightly different, with the a single digit at start that stands for model year folled by the three digit axle housing Id number and then a letter suffix (this suffix will sometimes appear on tag line as well). Thus an 8 inch housing used in a 68 Mustang would have "8930A" in the box labeled "Axle" on its build sheet, and most likely just the "930" or "930A" on axle tag itself. A similar build sheet for a 67 Mustang with an 8 inch housing would have "7930A" etc.. Axle housing id numbers I have are the following: 831- 68/69 Fairlane/Comet/Cyclone/Torino 8 inch, 868 -68/69 Fairlane/Comet/Cyclone/Torino 9 inch, 903- 67 to 69 Mustang 7 1/4 inch, 913- 65/66 Mustang 8 inch, 930- 67 to 69 Mustang 8 inch, 931- 67 to 69 Cougar 8 inch, 996- 67 to 69 Mustang 9 inch. Tags are generally found attached to the passenger side of carrier assembly secured by one of the nuts on the housing studs. Here are some examples I have:

Above is the earliest style tag I have seen used (mainly on 57/58 Fords), it is quite simple - just the ratio given, here 3.56.

Another early style tag used by Ford, this one is off a 62 Galaxy with a 3.00 open 9 inch.Tag reads C2AA4001 DV 100,second line:: 3.00 1MA

Here is a common Mustang tag WCZ-V identifies it as a 67-70 Mustang and 67-68 Cougar 8" rear with 2.79 ratio, open. Note no L between 2 and 7 on second line.
A "posi", equa-lock or traction lock rear is identified by an "L" in between the 1st and 2nd digits of the ratio given on the second line of tag. Here is a 2L80 ratio with tag number WDJ-B,which corresponds to a 8 inch used in 65-66 Mustangs.

How to identify a “Posi”  The two basic types of “posi” units (posi is the G.M. name for its positive traction system which has been become a part of the nomenclature) are the early Equa lock and the subsequent Traction lock units ( I will refer to them here as “spools” to simplify things). I am not exactly sure when the Equa-locs first appeared, early units are scarce – I haven’t seen many prior to 1964/65 and these are quite rare. From what I have seen the Equa locs were used up until 1969, which is when I believe the Traction Loc units first appeared. There are visual and internal differences between the two spools and most parts do not interchange.

Shown above is an example of an equa loc in its carrier, you will note the recessed bolt holes and 5/8” headed bolts, as well the rough cast appearance of the cover assembly, it is not machined as it is in the Traction Loc units.
Internally the number of clutch disc and plates differs between the equa loc and trac loc spools, the equa loc having only 3 fiber plates and 4 steel with one large beveled spring applying force. The trac loc unit utilizes 4 fiber plates and 5 steel plates, with 4 smaller springs applying force.Both equa lock and trac loc units were available in 2 pin and 4 pin varieties, in either 28 spline or 31 spline versions.The four pin 31 spline unit would be more commonly found as a trac loc piece. The four pin being the heavier duty unit utilizing 4 spider gears vs just two in the two pin variety (as noted in figure above a four pin variety will have actually just 3 pins and a two pin will in reality just have 1 pin- the number of spider gears is actually what is being referred to).Shown below are the internals of a four pin equa loc, note the five “fingers” on the steel clutch plates-the tiny circular tabs on outer edge- (trac loc units will have only 4).

 I came across at the web site kevinstang.comI hope he does not mind me sharing this information with you.


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