Ford 8.8 Differential Specificationsby Rob Wagner
Ford developed the 8.8-inch differential primarily for its trucks, sport utility vehicles and vans, but some mid- and full-size Mercury cars also featured the equipment. Numerous versions of the 8.8 with different gear ratios and number of gear teeth and splines are on the market.
The 8.8-inch differential feature six gear ratios: 3.08-to-1, 3.27-to-1, 3.31-to-1, 3.55-to-1, 3.73-to-1 and 4.10-to-1, according to Drivetrain. Gear ratios depend on the year and model of the Ford vehicle. The ring gear measures 8.8 inches in diameter with the single-piece case bolted with 10 7/16X20-inch threaded bolts. The pinion gear measures 1.626 inches in diameter with a 28-spline axle shaft through 2001, and 31 splines beginning in 2002.
Assembly Torque Specifications
The cover bolt assembly must be tightened to 28 to 38 foot-pounds. The ringer gear backlash requires .008 to .015 foot-pounds. Attaching the ring gear bolt to the case requires 70 to 85 foot-pounds of torque.
Ford used the 8.8-inch differential on the 1980s and 1990s four-liter Aerostar vans, Bronco and Explorer SUVs, four-liter compact Ranger pickups, full-size F-150 and F-250 pickups and Mercury Capris and Cougars. Contemporary F-Series and Rangers continue to use the 8.8-inch differential.