Ford 9" Replacement for Mopar A,B,E-body.
Bolt in Ford 9" assembly includes 31 to 40 spline axles, 1/2” or 5/8" wheel studs, axle bearings, Posi, Truetrack, or Spool, standard or Pro gears, 1350 series yoke. Breather vent, filler and drain plug fully set up. Custom widths are available at no extra charge.
The Basics: Leave the default options selected below and you have the makings of a great 9" Rearend for your Mopar! Just select the body style and leave the rest to us. (Of course you may want to add a set of brakes.) For those looking for more details, keep reading and choose from the other options available here. Never be afraid to call and have a discussion with us about any questions you may have or add a note during checkout and we'll get back to you. Please allow two to three weeks for assembly. Each rearend is custom built for your specific application and therefore unreturnable.
Nodular case: The S-Series nodular iron case is a stout foundation for any Street / Track application. The package contains the S-series iron case, Ford cast iron Daytona pinion support, clutch style posi unit, Standard gear, and S-series 1350 yoke with u-bolts. Upgrades to the differential, a forged aluminum pinion support, and chrome moly yoke are available.
Aluminum case: The HD Pro aluminum case is designed for Drag Race applications and for the most abusive Hi-Performance street/strip applications. Crafted from 206-T4 heat treated aluminum. This premium aluminum has a 12% higher yield strength and a 32% higher tensile strength, compared to commonly used 356-T6 aluminum. The billet aluminum pinion support has a unique oil channel that is machined 360º into the support to maximize oil flow to the pinion bearings as well as a large slot in the front to further boost oil circulation. The support is in contact with the bore of the case in two locations as opposed to one as found in normal cases. This additional contact area holds the pinion shaft much more securely resulting in better bearing and gear life. The tail bearing is oversized to handle more load and greater RPM than a stock tail bearing. Billet aluminum main caps encapsulate chrome-moly studs, provides the utmost support for the carrier bearings and significantly reduces ring gear deflection.
Clutch Systems: Uses a series of friction plates between the side gear and the case. Standard Duty units have them behind one side gear, Heavy Duty have them behind both. There is a spring or springs that apply tension between the case, clutch pack(s), and the side gears . By increasing friction in this way, it requires more load variation before the clutches release and allow the gears to start rotating and speed-up the outer wheel. The number of plates, their material, and spring pressure will alter the release point. The clutch packs can be replaced when worn-out.
Truetrack: The 9” Truetrack is a helical gear differential that offers smooth and progressive power transfer. It’s superior design and quality make it ideal for the most abusive Street/Track applications. The torque biasing S-Trac is purely mechanical, which eliminates the need for clutches. It provides quiet operation, while maximizing tire traction and vehicle acceleration. The forged steel case halves are heat treated and fully machined to minimize weight and provide a rigid mounting surface for the ring gear, resulting in improved gear life. Internal gear pocket geometry is designed to minimize stress risers increasing component life. The housing encapsulates precision manufactured gears, including 9310 steel pinion gears that provide exceptional strength. All internal gears, pinion Lubrication: The differential will best determine the proper gear lube. Always follow the recommendations of the differential manufacturer. In general, clutch style posi units or cone type systems require a quality petroleum based gear lube along with a bottle of friction modifier. For helical gear units, and side gears, are vacuum heat treated to increase strength and also cold treated to extend service life while reducing wear. A dry film solid lubricant coating is applied to friction surfaces to minimize wear. The S-Trac is recommended for full bodied street/track cars that run the 1/4 mile in the low 9 seconds or slower. For Drag Race Only vehicles, a spool is highly recommended. The seamless operation make it also ideal for Road Racing, Off-Road and Autocross. This premium unit carries a limited lifetime replacement warranty to the original purchaser.
Lockers: A Locker is a mechanical unit that is sensitive to torque application. It will lock (drive both wheels) under acceleration, or unlock (allow the axles to turn at different rates) during coast or deceleration. A very strong piece, since it doesn’t use any clutches or cones that can wear out, which made it a good choice for it’s original truck application. Since driver input mainly determines whether the unit is locked or not, it can be very frustrating to a driver who is unfamiliar with the operation of the differential. Hard acceleration during a turn will cause the unit to lock and skid the tire. Between lock and unlock, a distinctive “clunk” can be heard. During a properly executed turn, clicking will be audible since locking teeth are allowed to jump each other inside the unit.
Spool: A spool is one solid part that replaces all components of a differential. It will always turn both axles at the same speed with an equal amount of force. Due to the simplistic design, it is much stronger and lighter than any differential. It also allows the use of larger axles that can handle greater amounts of torque. This makes it the best choice for Drag Racing, Drifting, and other forms of motorsports that require uninterrupted transfer of power to both wheels. Spools should never be considered for a street application.
Most applications would use a street gear, however for a softer, faster wearing material designed to absorb impact better, Pro Series ring and pinions are available for drag race only applications.
Brake size depends on wheel diameter, as running the largest you can fit will stop the car the best. 11" rotors fit in most 15" wheels and some 15's can handle the 12.19" rotors. 17" wheels are more ideal for the 12.19" and 12.88" brakes and an 18" wheel would be most likely to accomodate a 14" rotor. With all the thousands of wheels on the market there are always exceptions.
If running leafs, let us weld on the perches for you, however if you are considering our Pro-Link or Ladder bar suspension don't spend the money, as they won't be required. Magnum Force Leaf springs drop the ride height a couple of inches and offer a much beefier version of the original springs for better handling and resistance to axle wind up for better traction/accleration. The Pro-link or Ladder bar suspension will make more tire clearance by elimination the leafs, offering some adjustability and quicker 60ft times, but that's a topic for another time.
A back brace welds to the back of the 9" housing and increases the stiffness of the housing substantially. Often chosen for race cars, its looks can't be overstated either.