Hidden under the truck, silently spinning away and delivering the engine's power to the ground, the axle and its differential may prove the weak link in your drivetrain if you're running larger tires or a bigger engine. Which, let's face it, you should be. Old S10s are just rolling frames begging for V-8 power, and the Borg-Warner axle isn't going to take that kind of torque. And the "Corporate" Chevrolet axle uses C-Clip retainers, which are accidents waiting to happen. Fortunately, removal and replacement with a stronger junkyard unit is pretty straightforward -- less than an hour-long project at the hands of an experienced mechanic.
Instructions
- 1
Break the rear lug nuts loose, and kick a set of chocks in front of the front wheels. Slide a floor jack under the rear frame crossmember, and lift the truck until the rear tires dangle about four to six inches from the floor. Drop the frame down on a set of jackstands, and allow the tires to dangle in the air. Spray some penetrating oil on the long bolts that secure the leaf springs to the shackles, and the shackles to the frame. Thoroughly douse the bolts, nuts and threads, and allow them to sit. While you're waiting, slide your floor jack under the differential and raise it to lightly support the axle.
2Remove the bolts that secure the driveshaft to the differential, and push the driveshaft forward into the transmission to remove it. Using a socket and wrench, remove the through-bolts that connect the rear shackles to the frame. Use a line wrench to remove the brake flex lines from the drum brake assembly. Try to catch any brake fluid that leaks out.
3Remove the retaining clip from the parking brake cable where it slides into the axle bracket. Using a long-handled screwdriver, lever the parking brake hook forward to release the retainer at the end. You may find this a bit easier if you adjust the brake cable so that it's as loose as possible. Pull the parking brake cable sleeve out of the retaining bracket.
4Using a ratchet and wrench, break loose the through-bolts that connect the rear spring shackles to the chassis. To get the bolts all the way out, you may find it expedient to tap the bolt outward from the inside with a hammer, then grab the bolt shank next to the head with a pair of pliers. Tap the pliers with your hammer to slide the bolt out. Repeat for the other rear shackle, and lower your axle to the ground with the jack. Remove the front shackle-to-frame bolts in the same manner, and roll the axle on the tires out from under the truck.
5The specifics at this point will vary wildly depending on what axle you're replacing this one with, and what the new axle came with. A decent junkyard axle may come with everything you just removed from your truck, or you may need to transfer the springs, parts of the brake assembly, the axle shafts, differential, wheels and tires or any number of other things from the original axle to the replacement. If you're using a larger 12-bolt, 9-inch or Dana 60, then you may have to make lots of little changes to the axle and driveshaft, and buy new springs. There are far too many factors to cover here, so, from this point forward, we'll assume that you're replacing the entire assembly (springs, shackles, brakes, wheels and all) just as you took it out.
6Grease the smooth center shanks of all your through-bolts to reduces squeaks, rattles and binding. Roll the axle back under the truck; installation, at this point is the reverse of removal. Fill the differential with fresh oil (preferably synthetic), and torque the driveshaft bolts to 15 foot-pounds. Torque the axle U-bolts to 85 foot-pounds, and all of the shackle bolts to 92 foot-pounds. Medium (blue) threadlocker is optional, but recommended, on the axle and driveshaft bolts. If using a different axle, research vehicles with that axle to find the appropriate driveshaft bolt torque specs.
7Reconnect the parking brake just as you took it out, and reconnect the brake lines using a line wrench. At this point, the axle is functional, but you'll still need to bleed the rear brakes and adjust the parking brake cable. Again, procedures will vary somewhat depending on what you replaced the original axle with, and what kind of brake assembly it came with. To adjust the parking brake cable, pull the brake lever in the cab slightly out; it should ratchet by two notches.
8Lift the rear axle off the ground, and adjust the cable tightness until you feel a bit of resistance when trying to spin the dangling tires. Release the parking brake, and feel and listen for the brakes dragging. Then fully engage the parking brake -- the wheels should be solidly stuck in place. After bleeding the brakes, don't forget to go through the drum adjustment procedure, and then re-check your parking brake to ensure that drum adjustment hasn't altered its engagement. Afterward, you'd be wise to take the truck to a shop and have them perform a four-wheel alignment.
