VW Rear Disc Brake Piston Retraction And Pad Replacement -

VW Rear Disc Brake Piston Retraction And Pad Replacement

With Volkswagen (VW) rear disc brakes, the parking brake is integrated into the caliper. A ratchet mechanism inside the caliper is supposed to automatically adjust the travel of the caliper to maintain the proper clearance between the pad and rotor.

The parking brake mechanism on some VW rear parking brakes can stick due to debris in the arm.
The parking brake mechanism on some VW rear parking brakes can stick due to debris in the arm.

With Volkswagen (VW) rear disc brakes, the parking brake is integrated into the caliper. A ratchet mechanism inside the caliper is supposed to automatically adjust the travel of the caliper to maintain the proper clearance between the pad and rotor. The majority of vehicles you will see at your shop will have cable actuated parking brake mechanisms. Some later models have electronic parking brake mechanisms with motors on the caliper.

In actual operation, the ratchet can sometimes get stuck, frozen or just not work properly, especially after a pad replacement. When replacing the rear pads, you’ll need to turn and compress the piston back into the caliper with care to prevent damage to the ratchet. The best way to do this is with a caliper resetting tool available from many manufacturers. Do not use pliers that could damage the boot.

The caliper pistons turn clockwise to retract, so you’ll need to turn and compress in small steps, being careful not to put too much pressure on the adjusting mechanism. After resetting the caliper piston, pad replacement is the same as the front. The same inspection points are important here as well — the sliders and the pad carrier. On early cars, you’ll need to remove the wheel bearings and races to replace the rotor. Make sure you have seals available, as the factory ones don’t like to come out. When pressing the pistons back into the caliper, I use a bleed bottle connected to the open bleeder to prevent pushing fluid back into the reservoir. Especially on ABS cars, this can prevent problems associated with contamination.

On some VW models, the caliper brackets can cause the brake pads to drag if they are not cleaned and serviced.
On some VW models, the caliper brackets can cause the brake pads to drag if they are not cleaned and serviced.

Pad replacement is the same on all models with rear disc brakes and is accomplished by removing the slide pins and pulling the “knuckle” off of the pad carrier. On later models, the inner pad is clipped to the caliper. The important points to inspect on either design are the caliper slide pins, which should be coated with a high-temperature silicone grease designed for brake use. On cars where the pins are floating in the pad carrier, always remove them, clean and lubricate them and make sure they are free to move throughout their normal range. Also look closely at the surfaces of the pad carrier where they have been wearing on the carrier. Clean this area and lightly file it if the divots are so deep that new pads may get caught during their service life. On some models, there are still thin metal strips that are replaced with the pads to maintain a smooth surface.

Courtesy Import Car.

You May Also Like

Updating Your TPMS Tools Regularly Matters

You can ensure your read is accurate by updating your tool regularly.

Courtesy of Tire Review by Yanick Leduc

Picture this: Mark, an experienced tire service technician, is on the phone with a technical support representative from his TPMS supplier, inquiring why his new sensors don’t seem to work properly with the 2019 Silverado he’s servicing.

Mark: “The truck doesn’t seem to pick up the signal from the new sensor!”

Cabin Air Filters

Cabin air filters will protect the health and well-being of the driver and passengers.

Diagnostic Procedures For Stop/Start Systems

Stop/start technology is more than just a switch wired to the brake pedal and starter.

Brake Pad Wear Sensors

Brake pad wear sensors have been around for years and continue to evolve.

Topology and Your Scan Tool

Topology influences how you access the modules with your scan tool.

Other Posts

Ride Control Diagnostics From Tire Wear Clues

Learning how to read the tire and communicate your findings is the key to ride control service.

Understanding Engine Timing- Chains, Gears and Belts

Engine timing is critical for overall performance.

Air Filters and Fuel Trims

Modern engines rely on precise airflow and oxygen sensor data for optimal performance.

Mercedes Ignition Coil Pack Diagnostics

Replacing a single coil might not be the best approach to curing an engine of a chronic misfire.