Before we review June's restoration progress, we should take a brief look at the CCKW's drivetrain for an overview of how the major components actually interconnect. While each of the CCKW's three axles receives drive power, it is impractical to connect them directly to the gearbox/transmission as one might for a rear-wheel drive automobile. Instead, the gearbox connects with a two-speed transfer case (see shaft B in the image below) which then redistributes drive power to each axle via additional drive shafts. Shaft A connects to the front axle's differential, while shaft C connects to the intermediate axle's differential. Transferring drive power to the rear axle involves additional complexity however, since the intermediate axle is quite bulky and blocks a direct route from the transfer case. To negotiate this issue, GMC added a "pillow block" (shaft F) to link shafts D and E. We should also note that a universal joint at each end of each drive shaft permits their smooth operation at different rotational axes to one another.
Much of this month's work focused upon rebuilding the differential units. As noted in our most recent report, Mil-Spec dismounted the differentials in the rear and intermediate axles for overhaul back in May. The team had to replace most of the bearings due to their deteriorated state. Furthermore, the input yoke shafts on each unit revealed significant scoring. To solve this problem, the restoration team installed "speedi-sleeves" over the damaged surfaces to permit a proper seal following reassembly. While a WWII-era maintenance shop would have discarded and replaced such worn components, it is always gratifying when modern repair techniques allow the safe return of original parts to service. In June, Mil-Spec reinstalled the fully-overhauled differentials for the intermediate and rear axles on the truck. They are presently working on the front axle's differential unit.
This month, the restoration team also worked on components for the braking system. This included the fabrication and installation of new brake lines and hoses for the rear axles, along with the installation of backing plates (brake flange plates) and freshly overhauled wheel cylinders.
Mil-Spec dismounted, inspected and overhauled the vehicle’s front axle and leaf spring suspension units, reinstalling them on the vehicle (as the images below reveal). They also began overhauling the vehicle's five drive shafts and the associated pillow block assembly.
Mil-Spec also bead-blasted/laser cleaned, primed and painted a number of the vehicle's ancillary components in preparation for their eventual reinstallation. This included items such as the master cylinder mount, hydrovac mounts, hand brake handle, transfer case linkage and shift handles, running board mounts, cab mounts, clutch pedal, brake pedal, pedal mount, throttle linkage, hand brake linkage, radiator supports, lower air dam, pintle hook brace and the pintle hook. Some of these parts are depicted in the images below.