How to Replace the Rear Differential in a Chevy Truckby Kevin Mclain
The rear differential in Chevy trucks is the main component that houses the rear axle gears and the rear driveshaft yoke. When the transmission is engaged, the yoke attached to the back of the transmission turns the drive shaft. The driveshaft then turns the yoke attached to the front of the rear differential. As the rear differential yoke is turning, the gears inside of the differential turn both of the rear axles, which then turns the rear wheels. The rear differential also houses the oil that keeps the gears lubricated and cool.
Park the Chevy truck on a flat surface and engage the parking brake.
Loosen the lug nuts from the rear wheels counter-clockwise with a tire tool.
Jack the rear end of the Chevy truck up and place the jack stands under the proper rear jacking points. Lower the rear end of the truck onto the jack stands.
Finish removing the lug nuts from the rear wheels. Pull the wheels off and place them flat down on the surface. Move to the rear driver-side wheel compartment and locate the four retainer bolts that hold the driver side rear axle into the axle housing. The axle housing mount is behind the brake assembly. Place a catch pan under the axle mount to catch the axle grease. Remove the four axle mount retainer bolts with an air impact wrench and a socket. Pull the axle straight out of the axle housing with your hands. If the axle is stuck, use the pry bar and pry the axle out of the housing.
Move to the passenger side wheel compartment and repeat the same process as outlined above for removing the passenger side rear axle. Slide under the rear of the Chevy truck and remove the four u-joint strap bolts from the rear drive shaft with the impact wrench and a socket. Pull the straps off and place them in a safe area. Pull back on the drive shaft yoke until there is enough room to lay the drive shaft on the ground.
Saturate completely the rear end yoke nut with rust-penetrating spray. Remove the yoke nut with the air impact wrench and a socket. Pull the yoke straight out of the rear end and place it and the nut in a safe place. Place a catch pan underneath the rear end and remove all of the rear-end housing bolts with the impact wrench and a socket, except for one. Place the jack under the center of the rear end chunk to catch the rear end when the last bolt is removed. Remove the last bolt from the rear end and wait for the oil to drain out of the rear end. Move the catch pan and lower the rear end to the ground and out from under the truck.
Scrape away the excess gasket off the rear end axle housing with a flat metal scraper. Wipe away the debris with clean rags. Make sure that the surface of the rear-end axle housing is completely cleaned and dried so that the new gasket will seat properly. Apply a thin bead of red high-temperature silicone around the base of the new rear end. Stick the gasket onto the base of the new rear end. Make sure that the holes of the new gasket match up with the holes of the new rear end.
Jack the new rear end up to the rear-end axle housing and work the jack back and forth until the new rear end is inside of the axle housing. Screw two bolts into the rear end and tighten down hand-tight to hold the rear end in place. Lower the jack and move it out of the way. Screw the other housing bolts into the rear end. Tighten the rear-end housing bolts in a alternating sequence so that the gasket will seat properly. Tighten the bolts until each bolt stops turning.
Slide the yoke back onto the rear end and screw the yoke nut onto the yoke. Tighten the yoke down completely with the air-impact wrench and a socket. Tighten the nut until it stops turning. Position the drive shaft yoke back to the rear-end yoke. Reattach the u-joint strap bolts and tighten with the air wrench and socket. Torque the strap bolts to 35-50 ft.-lbs with a torque wrench and a socket.
Slide the axles back into both sides of the axle housing and screw the retainer bolts in tight. Tighten the retainer bolts with the air wrench and socket. Torque the retainer bolts to 150 ft.-lbs with the torque wrench and a socket. Slide the wheels on and screw the lug nuts on tight. Jack the Chevy truck up and remove the jack stands. Lower the truck to the ground and remove the jack.
Slide back under the truck and remove the square fill plug from the back of the rear end with a 1/2-inch drive ratchet. Fill the rear end up with a hand pump and 75/90 rear end gear oil, until it begins to drip out of the fill plug hole. Screw the plug back in and tighten the plug down tight with the ratchet. Drive the truck around for about ten minutes to get the gear oil into the axle housing. Park the truck and recheck the gear oil inside of the rear end with your hand. The gear oil should be level with the bottom of the fill plug.
- The red high temperature silicone not only holds the gasket in place, but it also acts as a secondary gasket. The red high temperature silicone can be found at most all auto parts stores.
- The purpose for driving and rechecking the gear oil is so that the oil can get into all of the necessary areas.
- Be sure to tighten all of the rear-end housing bolts down in a alternating sequence or the gasket will not properly seal. This will result in the gear oil leaking out from around the gasket.
- Use caution when working under the Chevy truck when it is on jack stands.