2013-2016 Audi RS7 Brake Noise: Squeal, Grinding and Pulsation Causes

By Core Brake Parts Tech Team — Circleville, OH warehouse

Most brake noise on an early Audi RS7 comes from one of three things: pads squealing because of vibration between the pad, caliper and rotor; metal-on-metal grinding because the pads are worn to the backing plate; or a pulsing pedal caused by uneven rotor thickness. Before you buy anything, find out whether your car has the standard iron brakes or the optional carbon ceramic system, because the parts and the fix are completely different.

How the RS7 Brake System Is Built

The RS7 Sportback debuted at the Detroit auto show as a 2014 model. According to Audi's launch details, the standard car uses four internally vented discs with a weight-saving wave design, 390 mm (15.35 in) in diameter up front, gripped by six-piston calipers painted black, with red available as an option. Audi also offered 420 mm (16.54 in) carbon fiber ceramic front discs, identified by anthracite gray calipers.

This matters for noise diagnosis. Aftermarket street pads such as the Hawk Performance Ceramic set are made for iron rotors, and Hawk states they are not for vehicles equipped with carbon ceramic brakes. If your calipers are gray, stop here and work with parts built for that system.

Squeal: What It Means and How to Diagnose It

Wagner's technical guidance puts it simply: vibration is the main source of noise in a brake system, and rust, loose hardware and worn parts that no longer fit properly are what let it happen. On a heavy, powerful car like the RS7, a high-pitched squeal usually falls into one of these groups:

• New pads still bedding in. EBC notes squeal is common during the first 200 to 500 miles on new pads, and that used rotors with uneven surfaces or an edge lip make it last longer.
• Glazed pads or rotors. Power Stop explains that heat can leave the pad and rotor surfaces so smooth they no longer work as intended, and they squeal when hot.
• Missing or dry shims and hardware. Shims behind the pads damp vibration. Worn anti-rattle clips, springs and pins let the pad move and sing.
• Corroded caliper surfaces. EBC points out that corroded sliders and pins cause pad drag, which overheats the brake and leads to squeal. On the fixed six-piston RS7 caliper, the equivalent is dirty pad abutments and piston faces.
• Wear indicators. Some pads carry a mechanical wear indicator that makes noise on purpose when the pad is low. Check pad thickness before chasing anything else.

To diagnose it, pull the wheels and look at the pads: remaining friction material, even wear across the pad, glazing, and whether the shims are present. Look at the rotor face for a lip at the outer edge, heat spots or a mirror-smooth band.

Grinding: Stop Driving on It

Grinding is not a nuisance noise. Wagner's advice is direct: if you hear metal grinding on metal, have the brakes checked. On the RS7 it usually means one of these:

• The pad friction material is gone and the steel backing plate is cutting the rotor.
• A stone or piece of debris is trapped between the rotor and the splash shield or pad.
• Heavy rust on the rotor face after the car has sat, which usually clears after a few stops. If it does not, inspect.

If the backing plate has reached the rotor, the rotor is scored and must be replaced along with the pads. Do not try to save it; a scored rotor will chew through new pads and keep making noise.

Pulsation: Rotor Thickness Variation, Not "Warped" Rotors

A pedal that pulses or a steering wheel that shakes under braking is almost always disc thickness variation (DTV). Power Stop defines DTV as uneven clamping and rotation wearing the rotor unevenly, and lists the usual causes: rotors installed improperly, misaligned calipers, irregular friction patterns, and rust or dirt build-up. Lateral runout is related but different: the rotor thickness stays the same while the rotor wobbles side to side, and over time runout wears thickness variation into the rotor.

How to check it:

1. Measure rotor thickness with a micrometer in at least six spots around the rotor, about a quarter inch in from the edge. Power Stop gives 0.001 in (0.025 mm) as acceptable variation and flags anything over 0.006 in (0.15 mm) as DTV that calls for replacement.
2. Check runout with a dial indicator with the wheel nuts torqued, and clean the hub face before you measure. Rust between the hub and rotor hat throws the rotor out of true.
3. Use the minimum thickness stamped on the rotor, or the value in the factory service information, to decide whether a rotor can be machined or must be replaced.

The Fix and Which Parts to Use

For standard iron brakes, the durable fix for squeal or grinding is a fresh pad set on true rotors, installed with clean hardware. The Hawk Performance Ceramic front brake pad set HB731Z.620 is listed by Hawk for the front of the 2014 through 2016 RS7 and is described as extremely quiet and ultra-low dust. Confirm the fit by VIN and brake option before ordering, since this set is not for carbon ceramic cars. You can also browse our ceramic brake pads and full brake pad range.

If you measured DTV beyond the limit, found an edge lip, or the pads wore into the backing plate, replace the rotors too. See our brake rotors. Rotors are best replaced in axle pairs so both sides brake evenly.

What to Replace or Service at the Same Time

• Pad hardware: clips, springs, pins and shims. A brake hardware kit is cheap insurance against comeback noise.
• Wear sensors: if your pads use an electronic wear sensor and it has contacted the rotor, replace it with the pads so the warning works again.
• Caliper service: clean the pad abutments and piston faces. EBC recommends servicing or replacing calipers every 5 to 7 years to head off corrosion drag.
• Hub faces: wire-brush them clean before the new rotor goes on to prevent runout.
• Brake fluid: follow the interval and spec in your owner's manual or service schedule.

Lubrication matters: Wagner advises only a light coat of silicone brake lubricant on constrained-layer shims, never tacky compounds that can pull the shim loose, and nothing at all on insulators designed to run dry.

How Hard Is the Job?

A pad and rotor job on a standard-brake RS7 is within reach of an experienced home mechanic with a torque wrench and a dial indicator, but the brakes are large and heavy. Tighten caliper bolts and wheel nuts to the values in the factory service information, not by feel, and check the factory procedure before any rear brake work in case the parking brake needs a service mode. After installation, bed the pads in. Wagner's procedure is 20 slow-downs from 50 mph to 20 mph with light pressure, 30 seconds apart, with no panic stops. Proper bedding is one of the prevention steps Power Stop lists for avoiding DTV.

Frequently Asked Questions

Why do my new RS7 brake pads squeal?

New pads often squeal while they bed in; EBC puts that period at roughly 200 to 500 miles. If noise continues after that, check for missing shims, a lipped or uneven rotor, and dirty caliper contact points.

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

Look at the front calipers. Audi's launch details list black calipers, with red optional, on the standard 390 mm iron brakes, and anthracite gray calipers on the optional 420 mm carbon fiber ceramic brakes.

Can I put Hawk Performance Ceramic pads on carbon ceramic rotors?

No. Hawk states these pads are for iron rotors and not for vehicles equipped with carbon ceramic brakes.

Are my rotors warped if the pedal pulses?

Usually the rotor has uneven thickness rather than being bent. Measure it with a micrometer at six or more points; Power Stop flags more than 0.006 in of variation as needing replacement.

Is it safe to drive with grinding brakes?

No. Grinding usually means metal is contacting the rotor, which cuts braking performance and destroys the rotor. Have the brakes inspected before driving further.

Sources

1. Automotive Addicts - 2014 Audi RS7 Sportback debut - 390 mm wave-design front discs, six-piston calipers, optional 420 mm carbon ceramic discs with gray calipers
2. Hawk Performance - HB731Z.620 PC Street brake pads - RS7 front fitment, quiet and low-dust claims, not for carbon ceramic brakes
3. Power Stop - Measuring disc rotor run-outs, causes and preventions - DTV causes, measurement method and limits, prevention
4. Power Stop - What causes brake squeal - glazing from heat causes squeal
5. Wagner Brake - Brake system noise - vibration as the noise source, shim lubrication, burnish procedure, grinding advice
6. EBC Brakes - Brake squeal causes and cures - 200 to 500 mile bedding period, caliper corrosion, caliper service interval