1972 Chevy C10 - Bottoms Up

Inspect the axles and the pinion yoke where their respective seals ride for excess wear; my axles were somewhat questionable, which makes the new Yukon axles from Randy's worth it.

Greg loads everything into the parts washer for a bath so we can see what's really going on, even though most of the internals are getting replaced.

At this point, my 12-bolt was handed over to Brett, who is a skillful proctologist of the automotive type. He begins by prepping the new Yukon 3.42:1 ring-and-pinion set with a grinder, but there's no need to worry. In his many years building differentials, he's figured out a trick or two, and dressing the edges of the teeth on the ring-and-pinion is one of them. This is not a job for the shaky-handed, and it obviously negates returning these parts, but it helps to eliminate any burrs and sharp edges.

Doing so with a careful and steady hand makes the teeth look...

...like they came from Randy's like this!

Before the rear pinion bearing can be pressed onto the pinion, the shims need to be installed. Brett keeps a log of which differentials needed which shims, and it looked like a good starting place was going to be 0.030-inch of shims. We also figured out that the reason the rearend whined so much was from too shallow of a pinion depth due to only having 0.023-inch of shims, which left too much lash or gap between the ring-and-pinion teeth.

Place the shims over the pinion shaft before pressing the rear pinion bearing on, and yes, this should be done in a press.

Since we got the master rebuild kit from Randy's, which includes new bearings, races, seals, etc., the new races needed to be installed into the housing. Brett uses an old race to make sure the new one is pressed in all the way and doesn't just stop flush with the housing.

Before installing the pinion in the housing, slide the crush sleeve onto the pinion shaft, then put the pinion in place, followed by the front pinion bearing, and finally the yoke and its nut. Using an impact gun on the pinion nut and holding the yoke, Brett crushed the crush sleeve, which is used to slightly load the pinion bearings. How much do you crush it? Brett stops as soon as there is a small amount of drag, checks the drag, and stops at about 15 in-lb on new bearings.