Two problems related to axle shaft seal have been reported for the 1998 GMC Sierra. The most recently reported issues are listed below.
Front end shook while braking. Braking distance seemed normal. Vehicle was taken to dealer numerous times, and dealer replaced and turned front rotors four times. In may 2003, mechanic noticed rear axle seal was leaking grease onto rear brake drums, causing rear brakes to fail, seal was replaced. Currently, seal is leaking again, rear brake drums need to be replaced.
Initial problem 09/02/98 was both rear axle seals leaking causing brakes to fade. Again on 11/04/98 rear axle seals leaking, adjusted brakes. 11/06/98 brakes locking-up. 11/13/98 brakes grabbing, replaced both rear brake shoes, abs light on-module not activating brake release-replaced anti-lock brake module-master cyl bypassing-replaced master cyl. 01/20/99 abs light comes on-brake peddle hard to push-replaced abs brake valve. 03/23/99 brakes failed to slow vehicle-involved in accident-replaced abs pressure modulating valve.