Mercedes-Benz S420 Emergency Brake Cable Replacement Cost

In most vehicles the parking brake, also called the emergency brake, uses a cable connected to the rear brakes to manually set the brakes when the vehicle is not occupied. The parking brake cable and parking brake lever, found near the driver's seat, work in unison to hold the brakes until they are released by the driver.

The parking brake cable is held in a fixed position, and when the parking brake lever is pulled, pressed, or electronically engaged, the cable is pulled tight. For disc brake systems, this tension presses the rear brakes pads into the rear brake rotor, or, for drum brakes, the rear brake shoes will be pressed into the rear brake drum. Many modern vehicles with rear disc brakes have an auxiliary drum brake inside the brake rotor that is actuated by the cable. This protects the service brakes if the parking brake is left engaged while driving.

When setting the parking brake does not result in the wheels fully locking, the lever may be far easier to press or pull than normal. You may notice the vehicle tries to roll, and is caught by the transmission. This is particularly dangerous for manual transmission vehicles, as the transmission does not have a secondary lock, and the weight of the vehicle may allow it to roll, even if the gear selector is placed in a forward or reverse gear. Vehicles with electronically actuated parking brakes may display a warning on the drivers information center, alerting to the danger of the failed parking brake. Lastly, the parking lever can fail to return to the disengaged position after being released. In this situation the lever will exhibit a total loss of tension, but may provide resistance if manually pressed or pulled into the disengaged position.

It is not safe to operate any vehicle with any braking problem. If there is any sign that the brakes are not performing as originally intended, the vehicle should immediately be placed out of service and repaired. If the parking brake does not function properly, this could be a sign of rear brake failure, or could cause a runaway vehicle. When the vehicle is parked prior to repair, the wheels should be blocked from movement by a sturdy piece of material. This is normally a piece of wood, or a chock block. Get this fixed by a RepairPal Certified Shop

Most vehicles will never need the parking brake cable replaced, and those with problems will typically be greater than 10 years old with over 145,000 miles. This will fluctuate with operating conditions and use. vehicles in colder climates, where salt is used to clear roads of ice, will exhibit more frequent failure. This is because of the corrosive properties of salty water causing deterioration of the cable, or the cable’s protective sheath.

When the parking brake lever fails to engage the parking brake, the parking brake cable is often at fault. Normally when the parking brake lever is actuated, you can feel the tension on the parking brake cable as it moves inside the sheath, especially during engagement. If this does not occur, there may be breakage on the cable, normally at one end. If the parking brake cable is intact and the parking brakes do not engage, the cable may need adjustment. This will be noted as the parking brake will actuate at the wheel, but not sufficiently hold the vehicle parked on a hill. If no adjustment is possible, this may necessitate replacement of the cable, and further inspection to determine if other components require attention.

Replacement is typically a dirty job. The parking brake is connected to the undercarriage of the vehicle and is commonly covered with road grime, oil, or grease. The cable in the vehicle is removed first to avoid tracking these substances into the vehicle. Underneath the vehicle, the parking brake disconnects from the undercarriage, but the other end of the cable may be installed inside the drum, or auxiliary parking brake rotor hat. In these cases, the rear wheels must be removed to allow access to the brakes. For rear disc brakes with auxiliary parking brake drums, the brake caliper must be removed, and hung to prevent damage to brake lines. The rear caliper mounting bracket must be removed, followed by the rear brake rotor. For drum only rear brakes, the brakes must be completely unadjusted, and the brake drum may need to be pried off, hammered off, or a combination of the two. Once either the rear brake rotor or rear brake drum have been removed, the parking brake cable will be removed. For rear disc brakes with no auxiliary parking brake drum, the cable is simply disconnected from the exterior of the rear brake caliper, and only the wheel will need to be removed for access. Installation is the reverse order of these operations and adjustment of the parking brake cable or drum brakes is performed before the vehicle is returned to the ground.

The entire braking system should be inspected for proper operation whenever the Parking Brake system has been serviced.

The service brakes do not typically need attention for this replacement. However, if the rear brakes are drum brakes only they may require a full cleaning and adjustment service. For all types of parking brakes, if they failed to completely release, the rear brakes, or auxiliary parking brakes may need full servicing. Some parking brakes are adjusted automatically when the brake is used. This means that failure to use the parking brake over a long period of time may cause the parking brake cable seize, and manual adjustment may be necessary if repeated attempts to set the brake do not bring the cable back into proper adjustment. To avoid this, always set the parking brake whether or not the vehicle is parked on a hill.

The cost of brake cable replacement will vary by vehicle and type. Auxiliary parking brake drums cannot be resurfaced, as most resurfacing machines do not have the capability to reach into the tiny drums.If the parking brake is left on while driving for any extended period of time, the rear service brakes and parking brakes will need a complete brake service. To avoid this, be sure the parking brake is fully disengaged every time the vehicle is driven.