GMC 25792317 Front Axle Assembly (3.42 Ratio)

Power is transmitted from the front differential/axle to the front wheels through a pair of axle shafts. The inner end of the axle shafts are splined to the differential side gears. The outer end of each axle shaft has a stub shaft that is splined to the front hub and bearing assembly and locked in place with a large nut. The inner ends of the axle shafts are equipped with sliding constant velocity (CV) joints, which are capable of both angular and axial motion. Each inner CV joint assembly consists of a ball-and-cage type bearing and a housing in which the joint is free to slide in--and-out as the axle shaft moves up-and-down with the wheel. The outer ends of the axle shafts are also equipped with ball-and-cage type CV joints, which are capable of angular but not axial movement. Each outer CV joint consists of six caged ball bearings running between an inner race and the housing. The boots should be inspected periodically for damage and leaking lubricant. Torn CV joint boots must be replaced immediately or the joints will be damaged. If either boot of an axle shaft is damaged, that axle shaft must be removed in order to replace the boot. Should a boot be damaged, the CV joint can be disassembled and cleaned, but if any parts are damaged, the entire axle shaft assembly must be replaced as a unit. The most common symptom of worn or damaged CV joints, besides lubricant leaks, is a clicking noise in turns, a clunk when accelerating after coasting and vibration at highway speeds. To check for wear in the CV joints and axle shafts, grasp each axle (one at a time) and rotate it in both directions while holding the CV joint housings, feeling for play indicating worn splines or sloppy CV joints. Also check the axle shafts for cracks, dents and distortion.

Loosen the wheel lug nuts, raise the front of the vehicle and support it securely on jackstands. Remove the wheel. Remove the splash shield from under the vehicle. Pry off the hub cover using a hammer and chisel. Remove and discard the axle shaft/hub nut. To prevent the hub from rotating, brace a large prybar across two of the wheel studs or insert a long punch or screwdriver through the window in the brake caliper and into the disc cooling vanes. Disconnect the wheel speed sensor electrical connector and free the harness from its retainers. Unbolt the brake hose retainer where it joins the metal brake line at the frame. Remove the steering knuckle and simultaneously pull the axle shaft stub shaft out of the hub. If the stub shaft sticks in the hub splines, tap on the end of the shaft with a brass punch and a hammer. If that doesn't free the splines, push the axle shaft from the hub with a puller. Drive the inner end of the axle shaft away from the differential or intermediate shaft with a hammer and brass drift. Place the end of the brass drift against the inner axle shaft joint housing. Apply enough force to disengage the retaining ring on the inner end of the axle shaft from the differential or intermediate shaft. Remove the axle shaft from the differential. Installation is the reverse of removal, with the following additions. Before installing the axle shaft, lubricate the splines on the stub shaft with multi-purpose grease. Install a new axle shaft/hub nut and tighten it to the specific torque value. Tighten the suspension fasteners to the specific torque. Tighten the wheel lug nuts to the specific torque.

The front axle assembly comprises a differential and two driveaxles with inner and outer constant velocity (CV) joints.

Loosen the rear wheel lug nuts and raise the rear of the vehicle. Support it securely on jackstands and block the front wheels.