Ford Differentials: How to Rebuild the 8.8 and 9 Inch

The Ford 8.8- and 9-inch rear differentials are two of the most popular and best-performing differentials on the market. While the 8.8-inch differential is commonly used in late-model Mustangs, the 9-inch is the more popular and arguably the most dominant high-performance differential for muscle cars, hot rods, custom vehicles, and race cars. Built from 1957 to 1986, the 9-inch Ford differential is used in a huge range of high-performance Ford and non-Ford vehicles because of its rugged construction, easy-to-set-up design, and large aftermarket support. The 9-inch differential effectively transmits power to the ground for many classic Fords and hot rods of all types, but it is the choice of many GM muscle car owners and racers as well. These differentials have been used extensively and proven their mettle in racing and high-performance applications.

The Ford 8.8- and 9-inch must be rebuilt after extensive use and need a variety of different ratios for top performance and special applications. This Workbench book provides detailed step-by-step photos and information for rebuilding the differentials with the best equipment, installing the gear sets, and converting to Posi-Traction for a variety of applications. It describes how to disassemble the rear end, identify worn ring and pinion gears, other damage or wear, and shows step-by-step rebuilding of the differential. It also explains how to select the right differential hardware, bearings, seals, and other parts, as well as how to set ring and pinion backlash so that the rear end operates at peak efficiency.

Aftermarket 9-inch performance differentials from manufacturers including Currie, Moser and Strange are reviewed and you learn how to rebuild and set up these high-performance aftermarket differentials. In addition, this book provides a comprehensive identification chart to ensure readers properly identify the model and specifics of the 9-inch differential. Chapters include axle identification, inspection, and purchasing axles for rebuilding; differential tear down; ring and pinion gear removal; inspection and reassembly; drive axle choices; and more.

Joe Palazzolo is currently a Chief Engineer - Geared Products at GKN Driveline Torque Technology Group where he manages the mechanical design and development of new automotive torque transfer devices, concepts, and integration into production applications. His resume includes employment at Ford, Magna Powertrain (formerly New Venture Gear), Warn Industries, and GETRAG Corporation. His has also supported numerous race teams as well as building and maintaining his own motorsports and powersports vehicles. Joe is an ASE Certified Master Technician, holds a Bachelors Degree in Mechanical Engineering, and a Masters Degree specializing in Automotive Engineering. He has been a member of the Society of Automotive Engineers (SAE) for more than 18 years and is active in developing SAE standards. He has been teaching Drivetrain seminars for more than 10 years and a recipient of the Forest R. McFarland Award for distinction in professional development and education. He has received numerous patents for his innovative work and creativity in advancing vehicle mobility systems.

Table of Contents:
Acknowledgments 4
Introduction 5
What is a Workbench(R) Book? 6
Chapter 1: Axle History and Identification 7
8-Inch 8
9-Inch 9
8.8-Inch 12
Front Axle Applications 16
931/28-Inch 19
Part Numbers 19
Chapter 2: Axle Removal 23
Safety Equipment 23
General Procedures 24
Brake System Removal 25
Leaf Spring Removal 27
Chapter 3: 8.8-Inch Axle Disassembly and Inspection 30
Optional Upgrades 30
Disassembly Preparation 31
Axle Housing Disassembly 32
Traction-Lok Differential Disassembly 38
Chapter 4: 8.8-inch Axle Assembly 41
Traction-Lok Differential Assembly 42
Axle Housing, Wheel End Bearing and Seal Assembly 45
Ring and Pinion Gear Set Assembly 46
Chapter 5: 9-Inch Axle Disassembly and Inspection 56
Physical Differences 56
Strength Differences 56
Axle Shaft Splines 57
Disassembly Procedure 58
Brake Drums and Axle Shaft Dissambly 58
Third Member and Pinion Cartridge Removal 61
Summary 69
Chapter 6: 9-Inch Axle Assembly 70
Open-Differential Assembly 71
Traction-Lok Assembly 79
Third-Member Assembly 89
Axle Housing Assembly 100
Chapter 7: Ring and Pinion Assembly 108
Face-Hobbed Gears 111
Face-Milled Gears 113
Break-In Procedure 115
Gear Ratio Selection and Tooth Combinations 115
Chapter 8: Performance 9-Inch Axle Installation 117
Vehicle Acquisition and Inspection 117
Drivetrain Upgrades 119
Transmission Installation 119
Spring Pocket Kit Installation 121
Wheel Tub Installation 125
Axle Ratio Selection 129
Summary 130
Appendix: 9-Inch Axle Identification Codes 131
Source Guide 144