Poor performance of 1994 GMC Sonoma brakes may be due to the brakes or shoes being crystallized or hardened from heat. If the 94 GMC Sonoma brakes harden, they can no longer grab or stop the revolving of the brake drum or rotor. When 1994 GMC Sonoma brakes are overused due to people riding the brake pedal or excessive panic stopping it will cause the 94 GMC Sonoma brakes to harden. Brake materials need to stay soft in order to grab the drum or rotor to stop the vehicle.
If the power brake booster looses power, it can cause poor performance of the 1994 GMC Sonoma brakes. If the brake booster diaphragm or engine loses its vacuum, the 94 GMC Sonoma brakes will not perform properly. The rotors or brake drums may develop hot spots on the metal caused by the brakes being overheated from excessive use. The brake pads and shoes are the friction materials used for the 1994 GMC Sonoma brakes. If the rotors or brake drums have hardened areas, then the shoes and pads cannot get any gripping power to stop the vehicle.
If the 94 GMC Sonoma brakes are making grinding or squealing noises it usually means the pads are worn down and should be inspected. Manufacturers have placed wear indicators on the brake pads so drivers have a warning signal for the pads wearing out. That squealing noise is the indicators touching the brake rotor. Too many people wait until they hear the grinding noise before they take their vehicle in for a brake inspection. Once the grinding noise is heard, it means your brake pads are now completely worn through the indictors and the rotors could become damaged. Having your 1994 GMC Sonoma brakes checked when the squealing noise starts would save you money. It is cheaper to replace 94 GMC Sonoma brakes then it is to replace the rotors due to negligence.
The pulsation of the 94 GMC Sonoma brakes is caused by a warping of the drum or brake rotor. The up and down motion will be felt in the brake pedal when the 1994 GMC Sonoma brakes are applied. When the 94 GMC Sonoma brakes are worn, enough to create the pulsation feeling it usually means they are beyond adjustment stages and need to be replaced.