The Ford 9 inch is probably the most popular axle assembly for racing and high performance use. Regear yours with a Motive Gear ring and pinion gear set. They’re available in several versions:
Performance Gear Sets are ideal for street, circle track, and off-road use. They’re made from 8620 steel alloy, CNC-machined, and heat-treated on computer-controlled equipment for long life under extreme conditions. The gears are double lapped and have index tooth spacing with central contact patterning for precise gear mesh. Performance Gear Sets are available in ratios from 3.00:1 to 6.50:1.
Motive Gear also makes lightweight ‘AX’ gear sets to reduce drivetrain mass and improve acceleration on the race track. They’re available in ratios from 5.00:1 to 7.33:1 and require the use of a Motive Gear Daytona pinion support and solid spacer set.
Performance ‘Pro’ Gear Sets are the choice for drag racing. They’re manufactured to the same quality standards as the other Performance series gears but are made from 9310 steel alloy, which is softer than 8620 steel so the teeth can flex instead of cracking or breaking during hard launches. The Pro gears are also lightweight to reduce drivetrain mass and improve acceleration. They’re available in 3.70:1, 3.89:1, 4.29:1, 4.71:1, and 5.14:1 ratios.
You’re going to need some parts to install your new gear set. Motive Gear Master Ring and Pinion Installation Kits have everything required—carrier bearings; pinion and carrier shims; crush sleeve; pinion seal and nut; ring gear bolts; and a differential cover gasket.