2013-2016 Audi RS7 Brake Caliper Problems and Replacement

By Core Brake Parts Tech Team — Circleville, OH warehouse

The most common caliper problems on a 2013-2016 Audi RS7 are a sticking or slow-returning piston, seized pad slide pins or retaining hardware, and rear calipers that will not retract because the electric parking brake is still holding them. Before you buy anything, confirm whether the car has the standard steel brakes or the optional carbon ceramic package, because the calipers, rotors and pads are not interchangeable between the two.

How the RS7 brake system is built

Audi's launch press release for the RS 7 Sportback describes four internally vented discs with a weight-saving wave design, measuring 390 millimeters (15.35 in) up front. The steel friction rings are decoupled from aluminum brake caps by pins, which lets the ring expand with heat without warping the hat. Black painted six-piston calipers grip the front discs, with red calipers offered as an option.

The optional package swaps those parts for 420 millimeter (16.54 in) carbon fiber ceramic discs with anthracite gray calipers. That caliper color is the fastest way to tell the two systems apart at a glance, but on a used car always check the rotor itself: a carbon ceramic disc has a dull, dark gray composite face rather than the bright machined steel of the wave rotor.

Every RS7 of this generation also uses an electromechanical parking brake. The owner's manual tells you to pull the switch to apply it and to press the brake or accelerator pedal while pushing the switch to release it. That detail matters when you service the rear calipers, as covered below.

Symptoms of a failing RS7 caliper

• Pull to one side under braking. One front caliper has a piston that is sticking or a pad that is hung up in the caliper, so one side clamps harder than the other.
• Dragging and heat. After a normal drive, one wheel is noticeably hotter than the others, smells hot, or coasts poorly. A stuck piston is holding the pad against the rotor.
• Uneven pad wear. The inner and outer pads on one caliper, or the pads on one side of the car, are worn very differently. On a fixed six-piston caliper, one sticky piston pair can wear one pad faster.
• Brake fluid seepage. Wetness on the inside of the wheel, on the caliper body or around the bleeder. A leaking piston seal is a replace-or-rebuild item, not something to watch.
• Parking brake warning light or fault message. Usually points to the rear caliper motor, its wiring, or a rear pad job done without first putting the system into service mode.
• Low or soft pedal. Can be a caliper leak, but also air or moisture in the fluid. Check fluid condition before condemning calipers.

Keep normal noise in perspective. The manual notes that braking noises vary with speed, braking force, temperature and humidity, and that carbon ceramic rotors can be more audible at low speeds. A light squeal from a ceramic-rotor car in a parking lot is not a caliper failure on its own.

What causes RS7 caliper problems

Old brake fluid

Audi specifies DOT 4 fluid and calls for it to be replaced every two years. The owner's manual explains why: brake fluid absorbs moisture from the air, and when water content gets too high it can cause corrosion in the brake system and lowers the boiling point. Corrosion behind a caliper piston seal is the classic root cause of a sticking piston. On a car that has missed several fluid changes, expect to find at least one lazy piston.

Heat

This is a heavy, powerful car. Repeated hard stops, mountain descents without using engine braking, or track use cook the piston seals and dust boots over time. Once a dust boot cracks, road grit and water get to the piston surface and it starts to bind.

Hardware and pad fit

Seized pad pins, dry or corroded anti-rattle springs, and the wrong pads for the rotor type all cause drag and noise that looks like a caliper fault. Pads must match the rotor material: some aftermarket street pads, for example, are stated by the manufacturer to be for iron rotors only and incompatible with carbon ceramic rotors.

Rear service done wrong

The rear calipers carry the parking brake actuators. If someone forces the rear pistons back without first opening the calipers through a scan tool, the actuator can be damaged and the car will set a parking brake fault.

The fix: rebuild, replace, or just service

Start with the cheapest correct fix and work up:

1. Service the pads and hardware. Remove the pads, clean the caliper pad abutments and pins, replace worn springs and clips from a brake hardware kit, and fit fresh pads. Many "sticking caliper" complaints end here.
2. Flush the fluid. If the fluid is dark or past its two-year change, flush the whole system with new DOT 4 fluid meeting SAE J1703 before judging the calipers.
3. Rebuild or replace the caliper. A piston that will not retract with steady pressure, a torn dust boot with a pitted piston, or a fluid leak means the caliper needs seals and possibly pistons, or a replacement unit. Replacement brake calipers must match your system: a caliper for the 390 mm steel rotor will not fit the 420 mm carbon ceramic setup, and vice versa.

On the rear, the job adds the parking brake step. Ross-Tech's procedure for the closely related C7 Audi A6 parking brake uses the scan tool to put the system into lining change mode, which opens the calipers, and then uses the same function to close them after the new pads are installed. Their notes say the pistons do not move back by themselves and must be pushed in with a hand tool, that the basic settings must not be run while the brakes are disassembled, and that a fault code is normal while the system is in service mode. Use a factory-level scan tool that supports your RS7 and follow its procedure exactly.

What to replace at the same time

• Pads on both sides of the axle. Never pad one wheel. If a stuck caliper has overheated its pads, replace the full axle set. For steel-rotor cars, options include Hawk Performance Ceramic front pads (HB731Z.620), which Hawk lists for the RS7 and describes as a quiet, low-dust compound for iron rotors. Browse more in our ceramic brake pads collection.
• Rotors if they are heat-damaged. A dragging caliper often leaves a blued, grooved, or thickness-varied steel rotor. Replace those in axle pairs from our brake rotors range. Carbon ceramic rotors are a separate, much more expensive decision; have them inspected by someone who knows that system.
• Brake hoses. A collapsed flexible hose can trap pressure and mimic a stuck caliper. Inspect them any time a caliper is off, and replace cracked or swollen brake hoses.
• Fluid. Any time the hydraulic system is opened, bleed with fresh DOT 4.

After new pads go in, Audi says they need about 250 miles (400 km) to break in before they reach full braking effect, and longer on ceramic-rotor cars. Brake firmly but avoid hard stops during that period.

How hard is this job?

Front pads and hardware on a steel-brake RS7 are a reasonable job for an experienced home mechanic with proper jack stands and a torque wrench; torque all fasteners to the values in the factory service manual. Front caliper replacement adds bleeding, which is straightforward with a pressure bleeder. The rear is harder only because of the electric parking brake: without a scan tool that can open and close the calipers, leave the rear to a shop. Carbon ceramic systems are best left to a specialist because the rotors are easily chipped during handling and the parts are costly.

Frequently Asked Questions

How do I tell if my RS7 has carbon ceramic brakes?

Audi fitted carbon ceramic discs with anthracite gray calipers and 420 mm front discs, while standard cars have black or red six-piston calipers on 390 mm steel wave rotors. Confirm by looking at the rotor surface, since calipers can be repainted.

Can I put steel-brake calipers on a carbon ceramic RS7?

Not as a simple swap. The rotor diameters differ, so the calipers, brackets and pads are specific to each system. Converting from one to the other means changing the complete corner, not just the caliper.

Why is my parking brake light on after a rear brake job?

The rear calipers were most likely compressed without first opening them through the parking brake service mode, or the service mode was never ended. Scan the parking brake module, clear faults, and cycle the system as the procedure describes.

How often should RS7 brake fluid be changed?

Audi calls for new DOT 4 brake fluid every two years. Old fluid absorbs water, which lowers its boiling point and can corrode caliper internals.

Is a squeal at low speed a bad caliper?

Usually not. Audi notes that brake noise varies with conditions and that carbon ceramic rotors can be noisier at low speeds. Look for pulling, dragging heat, or fluid leaks before blaming a caliper.

Sources

1. Audi press release: Dynamics at their most beautiful, the Audi RS 7 - 390 mm wave discs, six-piston calipers, optional 420 mm carbon ceramic discs with anthracite gray calipers
2. Audi RS 7 Sportback owner's manual, electromechanical parking brake - parking brake operation
3. Audi RS 7 Sportback owner's manual, braking - pad break-in, brake noise, ceramic rotor noise
4. Audi RS 7 Sportback owner's manual, brake fluid - DOT 4 / SAE J1703 spec, two-year change, moisture and corrosion
5. Ross-Tech Wiki: Audi A6 (4G/4H) Parking Brake - lining change mode procedure and warnings
6. Hawk Performance HB731Z.620 - RS7 front pad application, iron rotors only