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Ford Ranger Rear Axles
The Ford Ranger came with the Ford 7.5-Inch rear end until 1990 (see note#1) . From 1990 on the Ranger could be found with either the Ford 7.5-Inch or the Ford 8.8-Inch rear axle.
1) 1986-up "Incomplete vehicles" also known as "Chassis Cabs" were frequently equipped with 8.8-Inch 28-spline axles, the 1986-1988 examples are distinctive as they are the only 8.8-Inch Ranger rears that have no provisions for a RABS sensor.
2) The 1990 & up 4.0-liter Rangers are ALWAYS equipped with the 8.8-inch 28-spline rear axle.
3) 1998-up 4x4 supercab Rangers regardless of powerplant are frequently equipped with 8.8-Inch axles
4) The FX4 Ranger was introduced in 2002 and always came with 4.10 gears only. The 31-spline Torsen 8.8-inch axle came only with the 2002 FX4 and 2003-up FX4 Level II and more recently was a separate option. The 2003-up FX4 (non-Level II) is essentially the same as the 1998-2002 Off-Road except that a regular Ford limited-slip in a regular 8.8-inch was included.
Swapping in an 8.8-inch 28-spline Ranger axle for the original
7.5-inch axle provides (according to Ford) a 35% increase in
strength. But this strength increase refers to the greater
strength of the gears and carrier bearings (Pinion bearings, axle
bearings and axle shafts are exactly the same) there is NO increase
in weight capacity If you are looking for greater strength for loads
created by severe offroad driving or towing you'll want to go to the
next step, the Explorer axle.
The 8.8-inch Explorer axle use 31-spline axle shaft. Increasing from a 28-spline to a 31-spline axle allegedly increases strength of the axle shaft by 34%, however I'll go by the capacity ratings of the axle assemblies provided by the manufacturer. Ford Rates the Ranger axle at 2750lbs and the Explorer axle at 3200lbs this is a 16% increase in strength, which admittedly may be as conservative as the estimate of axle strength. The Important thing about the Explorer axle assembly (besides its 31-spline shafts) is that its axles are larger in diameter at the outer bearing journal AND the larger diameter bearings used.
It's also important to note that the 1995+ Explorer 8.8-Inch axles come with disk brakes. This is the ultimate stock axle upgrade for your Ranger.
What axle do you have now?
You can identify which
axle you have by the tag attached to the inspection
Here is an example of an axle tag:
Looking at that tag, you can see the gear ratio stamped on the lower left and the axle size (ring gear diameter) stamped in the bottom middle.
Swapping a Ranger 7.5-inch to a Ranger 8.8-inch is a direct replacement. Swapping in a stronger 8.8-inch from an Explorer requires mounting the spring perches from under to over the axle. This should be done by a reputable welder. The 1995 & newer Explorer 8.8-inch axles have disk brakes. The master cylinders in the Rangers are not calibrated for rear disk brakes. When converting to rear disks you should replace your master cylinder with one from a rear disk brake Explorer.
Axle Width Differences:
People have asked about the widths of axle shafts to swap shafts from one axle to another.
The early 1983-1992 Ranger axles are 1-inch shorter than the 1993-up pieces (Both sides). This means that the an entire Ranger axle assembly from 1993-up is 2-inches wider than 1983-1992.
The right side Bronco II axle shaft is 1-5/8" wider than the 1983-1992 Ranger shaft. All of this additional width is on the passenger side. The drivers side shaft is the same length in either axle assembly.
On ALL Ranger/Bronco II's the drivers side axle shaft is longer than the passenger side.
is no difference between 7.5 & 8.8 axle shaft lengths provided you stay
in the same year window.
The 7.5-inch and 8.8-inch axles retain the axles using C-Clips. The C-Clip slides over the end of the axle shaft after it is inserted in to the side gears of the differential. If one of the clips break and falls out of its groove in the axle, the axle will slide out of the axle tube. C-Clip eliminators are available which hold the axle in the axle tube.
Ford Part# SVOM4220A
Moser Engineering 9300
Strange Engineering A1092
Serious Off-Roaders may consider installing an Axle Girdle. They Replace the existing inspection cover and provide support to the differential bearing caps. They also increase the fluid capacity.
Ford Part# M-4033-G (8.8-inch)
Ford Part# M-4033-J (7.5-inch)
Jegs Part# 6-9-101-8.8 (8.8-inch)
Heavy Duty Differential Covers:
A heavy duty differential cover is a must for the serious offroader. The stock stamped cover can bend and even get torn off if it catches on a rock or other solid trail obstacle. It can also get smashed in against the ring gear. Many companies now offer heavy duty covers like the one below from Solid Axle.
Rear axle codes can be found on the Safety Standard Certification label attached to the left drivers side door lock post. The code appears as a number or letter/number combination in the 'Axle' column of the label. The axle can also be identified by the tag on the axle differential cover bolt. See the diagram above to learn how to read the tag.
Axle codes for Ranger, Bronco II, Explorer
and Aerostar (included because 4.10 gears and limited slips are more
common than you'd expect)
Many people believe that a 4x4 truck sends power to all (4) wheels when it's in 4x4. That's usually not true. Generally in a Ranger the power is sent to the right rear wheel. If the truck has a limited slip, it will divert power to the left rear wheel when it feels the right rear wheel start to slip. The same holds true with the front axle, except the power is generally sent to the left wheel, and then diverted to the right.
A locker allows power to be sent to both rear wheels (or both front if in 4x4). There are (2) types of lockers, (1) that is engage permanently using compressed air or electric, and the type that engages power to both wheels when you apply power to the differential (mashing the go pedal!).
A locker is a must for any serious offroad enthusiast. You'll need the locker to send power to both wheels to get the best traction.
As mentioned, there are different types of lockers:
(1) An air locker solidly locks the rear end together using a small air-compressor attached to a locker in the differential. The advantage is that you can switch between an open and locked differential instead of having the locker engaging and disengaging.
(2) An electric locker. Similar to above but is controlled electrically instead of using compressed air.
(2) A spool (Not Recommended) solidly locks the rear axles but should only be used for off-road competition since it doesn't let the axles turn at different speeds while cornering.
(3) A Lincoln Locker (Same as spool) is simply welding the spider gears in the differential together.
(4) A Detroit locker replaces the whole carrier and unlocks when turning.
(5) A Lock-Right is the most popular because it replaces the existing spider gears, unlocks while turning, is affordable, and doesn't require setting up the ring and pinion like a Detroit Locker would.
Axle trusses are something that you can add to your axle to protect it from bending during serious off-road use, Especially if you like jumping your truck. Desert racers in particular should have one of these because getting airborn is "normal use" for them. For most people, the additional strength added by a truss is cheap insurance against damaging an expensive axle A slight bend in an axle tube will quickly wear out the axles shafts and bearings. It may also damage the differential itself as well as cause distinctive wear to your expensive offroad tires. And of course, serious bending of the housing can cause the axle to break leaving you stuck somewhere.
You use to be able to find bolt on axle trusses. They were typically a heavy metal rod that ran under the axle tube between the leaf spring perches and had a plate welded to it that sat under the differential (skid plate). They were held on with u-bolts near the spring perches along with a strap that went over the front of the differential housing. The problem was that they hung down and would catch on things sacrificing ground clearance.
Eventually people began fabricating trusses that welded right to the top of the axlehousing.
The truss shown above left is made by T & T Customs and is designed to be welded on to the top of a Ford 8.8 (above right).
Adding larger tires requires the use of lower (numerically higher) gears. To figure out what gears you need after a tire size change, click HERE.
If you really want a 9-inch rear axle you can swap in one from a late 1970's Lincoln Towncar which has a width of 57-inches. The spring pads will have to be relocated to the top of the axle and the driveshaft will need modified to accept the larger U-Joint. Currie Enterprises (714-528-6957) can custom make a Ford 9-inch to your specifications.
8.8-Inch Axle History:
Ford began using the 8.8-Inch axle in Rangers circa 1986 on "incomplete vehicles" aka "chassis cabs" (as mentioned above), but the 8.8" axles only became common in Rangers with the introduction of the 4.0L V6 in mid-1990. It began appearing in Explorers (and Mazda's Navajo twin) in 1991. It has also been used in 4.0L Aerostars (2wd ONLY, the 4.0 AWD Aerostars, strangely, are equipped with the 7.5-Inch axle), From mid 1984-up F-150 (Except for 5.4L "Lightning's" and Some 4x4 Supercabs which are equipped with the heavier-duty 9.75-Inch rear axle) 1984-1/2 on Full-size Broncos, and E-150 Econoline vans.
The 8.8 is also used in other Ford products such as Mustangs, Thunderbirds ("solid axle" 1987-1988 with 2.3 turbo engine and 5.0 "Sport" models), Crown Victorias and their equivalent Mercury and Lincoln products. However, because of their different suspensions, they make undesirable choices for swapping into a Ranger (unless you're looking to also swap to a four-link rear suspension for airbags and such).
An IRS (Independent Rear Suspension) version also appeared in the 1989-1997 Thunderbird, Mercury Cougar, (Though there is also a 7.5-Inch IRS in some V6 cars), the Lincoln Mark VIII and finally a very similar IRS suspension was adapted for the Mustang Cobra.
A wide range of gear ratios is available, from 3.08's up to 5.13's. An equally wide array of differentials is also available from open carriers to limited slips to lockers and spools.
8.8" axles can have either 28-spline or 31-spline axles.
All car applications use 28-spline axles, all truck applications use 31-spline axle shafts EXCEPT Rangers, which use 28-spline axles. However, even exceptions have exceptions......The 1999+ Ford Ranger FX4 come with the 31-spline 8.8-Inch axle and 4.10 or 4.56 gear ratios.
Gear sets are interchangeable between axles, regardless of the spline count. Differentials, however, are not.
The axle above in an 8.8-Inch from a 1995+ Ford Explorer. You can quickly identify it as an Explorer axle due to its rear disk brakes and the spring perches mounted below the axle tube instead of on the top. When swapping an Explorer 8.8-Inch axle in to a 4WD Ranger you need move the spring perches to the top of the axle tube.
What Comes With What?
How To Spot A 7.5-Inch and 8.8-Inch Axle:
It's pretty much all in the differential cover. Obviously all rear axles in Explorers are 8.8-Inch, but Rangers could of had either a 7.5-Inch or 8.7-Inch. Note the difference in the covers below: