Two-Piece Driveshaft, Slip Yoke, U-Joints & Carrier Bearing
Long-wheelbase two-piece tubular propeller shaft with a rubber-isolated center support bearing and three Spicer 1330 U-joints.
Role in the System
What This Assembly Is
Spanning the 138.8-inch SuperCab wheelbase from the transmission tailhousing to the rear axle pinion takes a two-piece tubular steel driveshaft: the 28-spline front slip yoke, the front coupling shaft, a frame-mounted center carrier support bearing, an intermediate slip spline, the rear main shaft, and three Spicer 1330 universal joints.
Mechanics & Physics
How the Subcomponents Work Together
Why Long-Wheelbase Trucks Use Two Shafts: A single thin-wall steel tube over six feet long would bow like a jump rope ("critical whirling speed") at highway RPM. Splitting the span in two raises the resonant frequency safely above top speed.
Plunging Slip Splines & Phased U-Joints: As the rear leaf springs compress over bumps, the rear axle moves along an arc that changes the distance to the transmission. Precision-machined 28-tooth internal splines inside the front slip yoke glide in and out on a film of ATF, while the U-joint yokes are phased in plane so velocity fluctuations cancel out.
Other Assemblies in This System
Ford 8.8-Inch Rear Axle Housing, Tubes & 10-Bolt Cover
Nodular cast-iron center carrier housing with 3.25-inch pressed steel axle tubes that carry the rear weight of the truck.
Ford 8.8-Inch Hypoid Ring & Pinion, Differential & RABS
Turns driveshaft torque 90 degrees, multiplies torque through an 8.8-inch hypoid ring gear, and splits wheel speeds in turns.
31-Spline Semi-Floating Axle Shafts, C-Clips & Bearings
Induction-hardened forged steel axle shafts retained inside the differential side gears by recessed C-clip locks.