Big 9-Inch OptionsFord's super-durable 9-inch differential was the company's first removable carrier rearend when it debuted in 1957. The 9-inch Ford, named for its 9-inch ring gear, has been the industry standard for performance rearends for five decades. In NASCAR, the Ford 9-inch is the only rearend anyone runs, including GM and Chrysler. Currie Enterprises has made the 9-inch Ford something of an institution, offering a variety of 9-inch designs for many uses and budgets. Let's take a look at what will fit your lifestyle and budget.
Ground PowerBuilding the right 9-inch Ford for your project begins with a solid foundation (the gearcases just mentioned). There's an array of gearcases (also known as chunks, pumpkins, third members, differentials, and more) to fit a variety of budgets and missions. Your budget, expected mission, and the amount of power your engine makes determine choice.
When it comes to differentials, there's a whole lot more going on inside the gearcase that mandates good, solid decision making during the planning stages. Noise and erratic operation make locking differentials a bad idea for the street. Every time you turn a corner, locking differentials rear their ugly heads with a lot of noise. This is why limited-slip differentials make more sense for street use.
Most limited-slip differentials use internal clutches, which slip quietly in the turns. Choosing a carrier also depends on how much power you intend to throw at it. Limited-slip carriers have their limits before horsepower and torque rip them to pieces. Each manufacturer will tell you the limits of a particular carrier. This isn't everything that's available from Currie, but here are some of the highlights.