Ford 8.8-Inch Rear Axle History & Specs

Introduction

The Ford 8.8-inch rear axle is a versatile and widely used axle found in trucks, SUVs, and performance cars. This guide covers its history, specifications, axle codes, and how to identify it, with a focus on the Ford Ranger and Explorer.

Ford 8.8-Inch Axle Usage Across Vehicles

The 8.8-inch axle was installed in multiple Ford models, including:

• Ford Ranger 4.0L (1990-2011)
• Ford Explorer (1991-2002; Explorer Sport until 2003)
• Ford Mustang (1986-2014)
• Ford F-150 (1983-2012, excluding heavy-duty 9.75-inch models)
• Ford Bronco (1983-1996)
• Ford Aerostar (1989-1997, 2WD 4.0L models)

History of the Ford 8.8-Inch Axle

• First Use: Introduced in Ford trucks in 1983.
• Ranger Chassis Cabs: 1986-1988 Rangers used 8.8 axles without RABS sensors.
• Ranger 4.0L Models: Standard from 1990 onward; all 4.0L Rangers have 8.8-inch axles.
• 1998-2011 SuperCab: Are frequently equipped with 8.8-Inch axles regardless of engine size
• FX4 Models: Most have 28-spline axles; 2002 FX4 and 2003-2007 FX4 Level II used 31-spline with optional Torsen differential.
• Explorer: Solid 8.8-inch axle used from 1991-2001; Explorer Sport 2002-2003 retained it.
• Aerostar: The 8.8-Inch axle was used in 2WD 4.0L Ford Aerostars
• F-150: 8.8-inch used from 1983-2012 except for 5.4L Lightning or higher GVWR models (9.75-inch axle).
• Bronco & Econoline: Used in the 1983-1996 full-size Bronco, and E150 Econoline vans
• Mustang and Other Ford Cars: Used in Mustangs, Thunderbirds, Crown Victorias, and Mercury/Lincoln equivalents.
• Wheel Bolt Patterns: Ranger, Explorer, and Mustang: 5×4.5″; F-150 and Bronco: 5×5.5″.

Mustang Note: Mustang owners have been known to take the left axles from 1990-1992 Ford Ranger 8.8-Inch axles to convert their axles from a 4-lug to a 5-lug wheel bolt pattern, or to replace an axleshaft.

The FX4 Ranger was introduced in 2002 and always came with 4.10 gears only.

For more on Torsen differentials, see What Is a Torsen Limited Slip Differential.

Disc Brakes on 8.8-Inch Axles

Some 8.8-inch axles come with rear disc brakes:

• The 1995-2003 Explorer 8.8-Inch axles come with disk brakes.
• The 2010-2011 Ford Ranger rear axles come with disc brakes.
• The 1999-2012 Ford F-150 8.8-Inch 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 Shaft Splines & Tube Diameters

• Ranger 28-spline (1990-2009); FX4 31-spline (2002 FX4, 2003-2007 FX4 Level II)
• Explorer 31-spline
• F-150 / Bronco 31-spline
• Aerostar 28-spline
• Mustang 28-spline (1986-2004); 31-spline (2005-2014)
• Tube diameters: 28-spline = 2.80″, 31-spline = 3.25″

NOTE: 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 2750 lbs and the Explorer axle at 3200 lbs 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.

Axle Bearings

• Ranger 28-spline: ID 1.399″, OD 2.25″ (1563 bearing)
• Ranger 2010-2011 28-spline & FX4 31-spline: 1559 bearing
• Explorer/F-150/Bronco 31-spline: ID 1.618″, OD 2.533″ (1559 bearing)

NOTE: The 28-spline 8.8-Inch axle uses the same size axle bearing (at the wheel end of the axle) as the Ford 7.5-Inch axle. Many Ranger owners have purchased new axle bearings only to find out that they were sold the bearing for the larger 31-spline 8.8-Inch axle. The exception is the 2010-2011 Ford Ranger 8.8-Inch rear axle. It uses the larger axle bearing.

Axle Width Differences

• 1990-1992 Ranger: 56.50″
• 1993-2009 Ranger: 58.50″
• 2010-2011 Ranger w/ discs: 58.50″ *
• 1991-2003 Explorer: 59.625″
• 1989-1997 Aerostar: 62.50″
• 1983-1996 Bronco: 65.125″
• Mustang: 1986-1993 = 59.25″, 1994-2004 = 61.25″
• 1989-1999 Crown Victoria: 62.50 inches

* The 2010-2011 Ford Ranger 8.8-inch axle is actually narrower and has shorter shafts than the 2009 and earlier models. Ford used rear disc brakes on the 2010-2011 Rangers, so Ford Shortened the axle housing and shafts to compensate for the extra width created by the disc brake setup. These shafts are not going to work in a 2009 and older Ford Ranger 8.8-inch axle.

For more information, check out ‘2010 Ford Ranger 8.8-Inch Axle vs 2004 8.8-Inch Axle‘

Specifications

 

 

 

Identification: Axle Tag & Federal Compliance Sticker

The axle tag on the differential cover or the Federal Compliance Sticker in the door jamb can identify axle type, gear ratio, and limited-slip options.

From the example above, you can see that the lower line shows the gear ratio, and ring gear diameter.

From that example, we can see that the tag above is a 7.5-inch axle with 3.73 gears.

The tag above is an 8.8-inch axle, and also has 3.73 gears, but there is a ‘L’ between the ‘3’ and the ’73’ indicating that it is a Limited Slip axle.

The tag above is from an 8.8-inch rear axle in a 2001 Ford Ranger 4×4 super cab with 4.10 gears.

If you look at the ‘AXLE’ section on the label above, you’ll see that this Ranger has a ‘F7’ axle code. Using the chart below, we know that this axle is a 7.5-Inch axle with a 4.10 limited slip.

Axle Codes

The following table lists Ford Ranger 8.8-inch and 7.5-inch axle codes:

 

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What Is A Torsen Limited Slip Differential

How To Spot A 31-Spline FX4 8.8-Inch Axle

FX4 8.8-Inch Axle Swap

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FAQ: Ford 8.8-Inch Axles

How can I identify a 8.8-inch axle?

Check the axle tag on the differential cover or look for rear disc brakes and spring perch placement. Ranger axles differ from Explorer axles in spline count and tube diameter.

Can I swap an Explorer 8.8 into a Ranger?

Yes, but you must move spring perches to the top of the axle tube. 31-spline Explorer axles are stronger than 28-spline Ranger axles.