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The Ford 8.8-Inch Solid Rear Axle

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Usage:

The Ford 8.8-Inch axle came in a few different vehicles including the:

Ford Mustang (1986-Current V8 models)

Ford Bronco (1983-1996)

Ford F-150 (1983-2012)

Ford Ranger (1990-2011 4.0L models)

Ford Aerostar (1989-1997)

Ford Explorer (1991-2001) (The Ford Explorer Sport still used the solid rear 8.8 until 2003)

Axle Shaft Splines:

Ford Mustang - The Ford Mustang 8.8-Inch axle from 1986-2004 used 28-spline shafts. From 2005 and on, the Ford Mustang 8.8-Inch axle used 31-spline shafts.

Ford Ranger - The Ford Ranger 8.8-Inch axle used 28-spline shafts. The exception is the 2002 FX4 and 2003 & newer FX4 Level II models which had 31-spline shafts.

Ford F-150 / Bronco - The Ford F-150 and Ford Bronco 8.8-Inch axles had 31-spline shafts.

8.8-Inch Axle History:

Ford began using the 8.8-Inch axle in trucks in 1983.

Ford began using the 8.8-Inch axle in Rangers around 1986 on 'incomplete vehicles' aka 'chassis cabs', but the 8.8-Inch axles didn't become common in the Ford Rangers until the introduction of the 4.0L V6 in mid-1990. All 4.0L Ford Rangers are equipped with 8.8-Inch axles

1998-2011 4x4 supercab Rangers regardless of powerplant are frequently equipped with 8.8-Inch axles

It came in Ford Explorers (and Mazda Navajo) in 1990 as a 1991 model year. The Ford Explorer used it until it switched to an independent rear suspension in 2002. The exception is the 2002-2003 Ford Explorer Sport which still used the solid rear 8.8-Inch axle. 

It was used in 2WD 4.0L Ford Aerostars, but the All-Wheel-Drive (AWD) Ford Aerostar was equipped with the 7.5-Inch axle. 

The Ford F-150 used the Ford 8.8-Inch axle From 1983-2012 except for 5.4L (including Lightning) and some 4x4 Supercabs and higher GVWR models which were equipped with the heavier-duty 9.75-Inch rear axle. It was also used in the 1983-1996 full-size Bronco, and E-150 Econoline vans.

The 8.8-Inch is also used in other Ford products such as Ford Mustangs, Ford Thunderbirds, Ford Crown Victorias, and their equivalent Mercury and Lincoln products. 

A wide range of gear ratios is available, from 3.08's up to 6.14's. An equally wide array of differentials is also available from open carriers to limited slips to lockers and spools.

8.8-Inch axles can have either 28-spline or 31-spline axles.

Gear sets are interchangeable between axles, regardless of the spline count. Differentials, however, are not.

Ford Ranger 8.8-Inch Axle Facts:

The Ford 8.8-Inch axle was found in 'incomplete' or 'chassis cab' vehicles starting in 1986.

The 1986-1988 8.8-Inch axles are distinctive as they are the only 8.8-Inch Ranger rears that have no provisions for a RABS sensor.

The Ford 8.8-Inch axle became common starting in 1990 when Ford introduced it with the new 4.0L V6 in the Ford Ranger.

All 4.0L Rangers are equipped with the 8.8-Inch axle.

1998-up 4x4 supercab Rangers regardless of powerplant are frequently equipped with 8.8-Inch axles

All Ford Ranger 8.8-Inch axles have 28-spline axle shafts except for the 2002 FX4 and 2003 & newer FX4 Level II models which had 31-spline shafts.

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.

Ford Ranger 8.8-Inch Axle versus Ford Explorer 8.8-Inch Axle

All 8.8-Inch Ford Explorer axles use 31-spline axle shafts. All 8.8-Inch Ford Ranger axles use 28-spline axle shafts (except FX4 and FX4 Level II which use 31-splines).

The Ford Ranger 28-spline 8.8-Inch axle tube is 3.00 inches in diameter.

The Ford Ranger 31-spline 8.8-Inch axle tube is 3.25 inches in diameter.

The Ford Explorer 31-spline 8.8-Inch axle tube is 3.25 inches in diameter.

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.

Bearing Example:

2000 Ford Ranger 8.8-Inch 28-spline axle bearing ID= 1.399", OD= 2.2948" (1563 series bearing)

1999 Ford Explorer 8.8-Inch 31-spline axle bearing ID= 1.1618", OD= 2.5333" (1559 series bearing)

EVERYTHING in the Ranger 8.8 and Explorer 8.8 is the same size (carrier bearings, pinion bearings/seals, ring gear, pinion, pinion nut, ring gear bolts, top and bottom spider gears) EXCEPT the side spider gears (the Ranger one has 28-splines and the Explorer has 31-splines), and the cross pin.

Disc brakes:

The 1995-2003 Explorer 8.8-Inch axles come with disk brakes. This is the ultimate stock axle upgrade for your Ranger.

The 2010-2011 Ford Ranger rear axles come with disc brakes.

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.

Axle Width Differences:

1990-1992 Ford Ranger 8.8-Inch Axle - 56-1/2 inches

1993-2009 Ford Ranger 8.8-inch Axle - 58-1/2 inches

1991-2003 Ford Explorer 8.8-Inch Axle - 59-1/2 inches

Specifications:

Ford 8.8-Inch Axle - Specifications - Ring Gear & Differential

 Ring Gear Diameter  8.8 Inch
 Ring Gear Bolts  (10) 7/16" x 20
 Differential Cover Bolts  10
 Pinion Stem  1.626 Inches
 Pinion Splines  28
 Pinion Bearing Preload (New)  14-19 in lb
 Pinion Bearing Preload (Used)  8-10 in lb
 Back Lash  .011"-.016"
 Ring Gear Bolt Torque  60 ft lb
 Bearing Cap Bolt Torque  60 ft lb
 Fluid Type

Use hypoid gear lubricant SAE 75W80 or 80W90 (Add 2 oz. friction modifier to axles with limited slips)

 Fluid Capacity

5 pints (expect to use 2-3 quarts if changing the fluid. More if you have an aftermarket heavy duty cover.

 

Ford 8.8-Inch Axle - Specifications - Axle Shaft

Vehicle Side Spline Diameter Length Bolt Circle Stud Size Bearing
1983-1992 Ford Ranger Right Hand 28-Spline 1.21 Inch 26.25 Inch 5 x 4-1/2 Inch 1/2 Inch Press 1563
1983-1992 Ford Ranger Left Hand 28-Spline 1.21 Inch 29.125 Inch 5 x 4-1/2 Inch 1/2 Inch Press 1563
1993-1997 Ford Ranger Right Hand 28-Spline 1.21 Inch 27.25 Inch 5 x 4-1/2 Inch 1/2 Inch Press 1563
1993-1997 Ford Ranger Left Hand 28-Spline 1.21 Inch 30.125 Inch 5 x 4-1/2 Inch 1/2 Inch Press 1563
1995-2002 Ford Explorer Right Hand 31-Spline 1.32 Inch 27.62 Inch 5 x 4-1/2 Inch 1/2 Inch Press 1559
1995-2002 Ford Explorer Left Hand 31-Spline 1.32 Inch 30.50 Inch 5 x 4-1/2 Inch 1/2 Inch Press 1559

 

Axle Dimensions
 
Ranger 1983-1997
7.5-Inch Axle
Ranger 1983-1997
8.8-Inch Axle
Ranger 1998-2009
7.5-Inch Axle
Ranger 1998-2009
8.8-Inch Axle

Bronco II 1984-1990

7.5 Inch Axle (1)

Ranger 2010-2011
7.5-Inch Axle
With Disc brakes
Ranger 2010-2011
8.8-Inch Axle
With Disc Brakes
Explorer 8.8
Width WMS-WMS 56-1/2 inches 56-1/2 inches 58-1/2 inches 58-1/2 inches 58 inches unk unk 59-1/2 inches
Axle tube diameter (1983-2009 models): 2.80 inches 2.80 inches 2.80 inches 2.80 inches 2.80 inches 3.25 inches 3.25 inches 3.25 inches
Pinion Offset Right Of Center unk 2 inches unk 2 inches 1-1/4 Inches unk 2 inches 2 inches
Pinion Offset Below Centerline unk 1.50 inches unk 1.50 inches unk unk 1.50 inches 1.5 inches
Pinion length (axle centerline to u-joint centerline): 11-5/8 inches 11-5/8 inches 11-5/8 inches 11-5/8 inches 11-5/8 inches 11-5/8 inches 11-5/8 inches 11-5/8 inches
Bottom Of Housing From Centerline 5-inches 5-3/4 inches 5 inches 5-3/4 inches 5 inches 5 inches 5-3/4 inches 5-3/4 inches
Stock Spring Perch Width 38-1/2 inches 38-1/2 inches 38-1/2 inches 38-1/2 inches 40-1/2 inches 38-1/2 inches 38-1/2 inches 38-1/2 inches
Axle Spline / Diameter 28 / 1.21 inches 28 / 1.21 inches 28 / 1.21 inches 28 / 1.21 inches 28 / 1.21 inches 28 / 1.21 inches 28 / 1.21 inches 31 / 1.32 inches
Pinion Stem Diameter 1.626 inches 1.626 inches 1.626 inches 1.626 inches 1.626 inches 1.626 inches 1.626 inches 1.626 inches
Ring Gear Diameter 7.50 inches 8.80 inches 7.50 inches 8.80 inches 7.50 inches 7.50 inches 8.80 inches 8.80 inches
(1) The Bronco II 7.5 inch rear axle is ~1-5/8 inches wider than the Ranger 7.5 inch axle. All the additional width is in the passenger side.

 Identifying Your Axle:

You can identify which axle you have by the tag attached to the inspection cover.  
 
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.

So looking at the axle tag above, you can see it's a 3.73 gear ratio with a limited slip in a 8.8 inch axle.

Axle Codes:

The Ford 8.8-Inch axle can also be identified by the sicker on the drivers door. Check out our Ford 7.5 & 8.8 Inch Axle Code page for a break down of codes.

Ford Explorer 8.8-Inch Axle Swap:

Interested in swapping the Ford Explorer 31-spline 8.8-Inch axle in to your Ford Ranger? Check out our Ford Explorer 8.8-Inch Axle Swap page.

 

 

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