If your parking brake (emergency brake) won’t hold the vehicle on a slope, or if it requires you to pull the lever far up before it engages, or if it simply doesn’t work at all, it’s a problem worth fixing beyond just convenience. In some states, a functional parking brake is required for vehicle inspection. More importantly, on even a moderate slope, a failed parking brake is a runaway vehicle risk. Here’s what causes parking brake failure and how Norm’s Auto Clinic fixes it.
How the Parking Brake Works
Most parking brakes apply the rear brakes mechanically via a cable — independent of the hydraulic brake system. When you pull the lever or press the foot pedal, a steel cable runs to the rear wheels and mechanically applies the brake. On vehicles with rear disc brakes, the caliper has a separate mechanical mechanism; on vehicles with rear drum brakes, the cable operates the brake shoes directly.
Common Causes of Parking Brake Failure
- Cable stretch — Steel cables stretch over time; the parking brake lever travels further before engaging. Adjustment can compensate for some stretch; replacement needed when stretched past adjustment range.
- Cable corrosion or seizure — Oklahoma humidity and road salt from occasional winter treatment cause cables to corrode inside their housings. A seized cable may apply unevenly or not release properly.
- Rear brake shoe wear (drum brakes) — The parking brake relies on the rear brake shoes; worn shoes provide less engagement.
- Parking brake lever ratchet failure — The ratchet mechanism that holds the lever in position can wear; the lever doesn’t hold its position.
- Rear caliper mechanism (disc brakes) — The integral parking brake mechanism in rear disc calipers can seize, preventing engagement or release.
- Electronic parking brake fault — Modern electric parking brakes rely on a motor and control module; faults illuminate a warning light and may disable the system.
Norm’s Auto Clinic performs parking brake adjustment, cable replacement, and rear brake service on all vehicles. Call (918) 279-8100 or visit 19 N. Broadway, Coweta, OK 74429. Serving Coweta, Broken Arrow, Wagoner, and the Tulsa area.