Depending on the year and manufacturing plant of your VW Passat, there could be a few different front braking systems in place that will vary slightly in procedure. Inspecting the brake system and purchasing a repair manual for your specific Passat is always recommended. The disc brake systems on Volkswagens use the same principle in hydraulic calipers as any other vehicle on the road, but there are slight variations in the tools required that VWs employ to complete the job.
Remove 1/3 of the brake fluid from the master cylinder, discard the fluid and then replace the cylinder cover. Apply the parking brake, and leave the front wheels in an unlocked position so you can move them when the Passat is elevated.
Crack the lug studs loose about 1/8 inch, using the ratchet and a 17-mm socket. Lift the Passat, and place the jack stands in a safe and secure position to support the car. Remove the lug studs and front wheels.
Inspect the caliper, looking through the front port to determine if the caliper is single piston or dual piston. If the caliper employs dual pistons, refer to the Tips section. There are a few different types of single-piston applications with slight variations in procedure. Look on the outside of the caliper housing for a outboard pad retaining spring. If applicable, use a screwdriver to remove this spring and then set it aside.
Locate and remove the caliper guide bolts. Remove the plastic caps to reveal the bolts, if applicable. Guide pin calipers require holding the inner retaining base of the guide pin with a thin-headed, opened-end wrench while removing the bolt with another wrench or a ratchet and socket. A different style caliper may require a 6- or 7-mm hex tool to remove the guide bolt while holding the retaining base. Some caliper applications only require the bottom guide bolt to be removed and then the caliper pivoted upward. Remove both guide bolts and then secure the caliper to the suspension with string to allow easier access to the pads.
Remove the pads from the mounting bracket. If the inboard pad is attached to the piston of the caliper, remove that first. Inspect the rotor for scoring or grooves and determine if they should be replaced. Compress the piston of the caliper inward using a caliper retracting tool or a large C-clamp.
Clean the mating surface of the mounting bracket and caliper where the pads come into contact using a small wire brush. Be thorough. Remove movable slides and bushings. Apply anti-seize compound to them liberally and replace them. Apply a coat of the compound on the mounting brackets where the pads tabs contact them. Be sure to cover both upper and lower rattle clips, being careful to clean any off that contacts the rotors.
Install the new pads by reversing the order. Be aware that unidirectional pads are sometimes used by the VW dealerships and should be installed with the arrow on the backing plate facing downward. Reverse the remaining procedure to complete the reinstallation and then proceed to the other side. Refer to the repair manual for the correct torque specifications on the specific Passat design you are working on when tightening the guide bolts and lug studs.
Pump the foot pedal until it feels firm, once the Passat is complete and then lowered back to the ground. Check and adjust the level of brake fluid in the master cylinder with the proper brake fluid.
Dual piston calipers employ four smaller pads instead of two. A Torx T-40 tool is required to remove the retaining bolts on the outboard pads. The pistons can be compressed by using a large pry tool and prying the outboard pads against the mounting bracket alternatively. Once the guide bolts are removed, remove the outboard pads and then remove the inboard pads. The remaining procedure is relatively similar.
Never allow a vehicle to be supported by a jack only. Always use jacks stands to support the vehicle. Always make sure the vehicle is parked on a level and suitable surface for lifting vehicles safely.