2013-2018 Audi RS6 Brake Noise: Squeal, Grinding and Pulsation Causes

By Core Brake Parts Tech Team — Circleville, OH warehouse

Brake noise on a 2013-2018 Audi RS6 (C7) almost always traces back to one of four things: pads that were never properly bedded, a worn front rotor with a lip at the outer edge, corroded or dry caliper hardware, or uneven pad deposits that make the pedal pulse. Grinding is the exception and means stop driving and inspect now, because it usually signals metal-to-metal contact. Before buying parts, confirm whether your car has the factory iron brakes or the optional carbon ceramic system, because the parts are not interchangeable.

Which Brakes Your C7 RS6 Has

Audi offered the C7 RS6 with two very different front brake systems. The standard setup uses large cast iron front rotors that measure 390 mm across and 36 mm thick when new, with a 34 mm minimum thickness listed by rotor makers who build to the OE dimensions. Audi also offered ceramic brakes with 420 mm front and 365 mm rear discs, intended for sustained hard use. A quick visual check usually settles it: ceramic discs have a dark, non-metallic, mottled face instead of bright machined iron.

One note for US owners: Audi states that the C7 RS6 Avant was not sold new in the United States, where the RS7 Sportback filled that role. The RS6 and RS7 of this generation share their front rotor fitment, so everything below applies to a C7 RS7 as well. Rotors such as our GiroDisc slotted front rotors for the C7 RS6 and RS7 are listed for iron-brake cars only and do not fit the carbon ceramic option.

Squeal: What It Means and How to Diagnose It

A high-pitched squeal is vibration. The pad, caliper and rotor resonate together at a frequency you can hear. EBC's technical team notes that squeal can happen with any pad, any brand and almost any vehicle, and that fresh pads commonly make some noise during the first few hundred miles before settling down. On a heavy, powerful car like the RS6 the pads are large, which gives them more surface to sing.

Work through it in this order:

• When did it start? Noise that began right after a pad change points to bedding, missing or reused shims, or pads installed on a worn rotor.
• Does it happen in reverse or as you release the pedal from a stop? EBC calls this creep noise, a low groan as the car starts rolling. It is common and usually harmless.
• Is it constant while driving with no pedal applied? That suggests a pad dragging on the rotor or a wear sensor or backing plate touching something. Check for uneven heat at each wheel after a drive.
• Look at the rotor edge. A raised lip at the outer rim of a used rotor means new pads are not seating across the full face, which prolongs noise.

Grinding: Stop and Inspect

Grinding is a harsher, lower sound, often felt in the pedal. On any car it most often means the friction material is gone and the steel backing plate is contacting the rotor. The other common cause is a stone or debris trapped between the rotor and the splash shield, which makes a scraping noise whether or not you are braking.

Pull the wheel and measure. On iron-brake cars, compare rotor thickness to the 34 mm minimum; a rotor scored by a backing plate is usually below that or too damaged to machine. If grinding comes from the rear, keep in mind that the C7 rear brakes use an electronic parking brake, so a faulty actuator or a caliper that was forced during a previous job can hold the pads against the disc.

Pulsation: Why the Pedal Shakes

A pulsing pedal or a shimmy through the steering wheel under braking is usually blamed on a warped rotor. In practice it is more often disc thickness variation: uneven spots of pad material transferred onto the rotor face, or rotor wear that is thicker in some places than others. Each time a thicker section passes through the caliper, clamp force changes and you feel it in the pedal.

Common causes on the RS6:

• New pads that were not bedded in, so the transfer layer went on unevenly.
• Holding the brake hard at a stop right after a very hot stop, which can imprint pad material onto one spot of the rotor.
• Corroded slide pins or sticking pistons that keep one pad in light contact, which EBC identifies as a cause of pad drag, overheating and noise.
• Uneven wheel bolt torque. Always torque the wheel bolts to the value in the factory service manual in a star pattern.

Two-piece floating rotors are designed to reduce this. Paragon, for example, states its C7 RS6 and RS7 floating rotors hold lateral run-out to within 0.03 mm and let the iron ring expand without deforming the hat. GiroDisc's C7 rotors use aluminum hats with replaceable iron rings.

The Fix and Which Part

Match the repair to the diagnosis:

1. Squeal with good pads and rotors: clean and lubricate the pad contact points and slide pins with a brake-specific grease, confirm the shims are in place, then re-bed the pads with a series of firm stops from moderate speed without coming to a full stop, followed by a cool-down drive.
2. Rotor lipped, below 34 mm, or pulsing: replace the front rotors as a pair and fit new pads at the same time. Browse brake rotors and brake pads, and confirm fitment for iron versus ceramic before ordering.
3. Dragging or seized caliper: EBC recommends servicing or exchanging calipers every 5 to 7 years. Rebuild or replace the caliper; see brake calipers.
4. Grinding to the backing plate: replace pads and rotors together, and inspect the caliper pistons and boots for heat damage.

Carbon ceramic discs are a different case. They are very expensive to replace and are assessed with Audi's own inspection method rather than a simple thickness check, so a ceramic car with noise or pulsation should go to an Audi-experienced shop first.

What to Replace at the Same Time and How Hard the Job Is

With new front rotors, replace the pads, the wear sensor if it has contacted the rotor, and any fatigued anti-rattle hardware from the brake hardware kits. Consider fresh brake fluid if it has not been changed on schedule; use the fluid type printed on the reservoir cap and in the owner's manual.

A front pad and rotor job on the RS6 is within reach of an experienced home mechanic with a torque wrench and jack stands, but the parts are large and heavy. The rear is harder. According to the Ross-Tech procedure for the C7 A6-family electronic parking brake, the calipers must be put into lining change mode with a scan tool before the pads can be removed, the car should be on a battery charger, and the brake should only be cycled with the pads and calipers installed on the rotors. Forcing a rear piston back without the scan tool can damage the actuator.

Frequently Asked Questions

Why do my new RS6 brakes squeal?

Fresh pads often make noise until they bed in over the first few hundred miles, especially if they were fitted to a used rotor with a worn edge. If noise continues, check shims, lubrication points and caliper slides.

Can I machine the front rotors instead of replacing them?

Iron rotors can be machined only if they stay above the 34 mm minimum thickness afterward. With a new thickness of 36 mm there is little material to remove, so replacement is often the practical choice.

Do iron rotors fit a car with the carbon ceramic option?

Not by simply swapping discs. Ceramic cars use a 420 mm front disc with matching calipers, while iron rotors like the GiroDisc set are listed only for cars with the factory iron brakes.

Why does my steering wheel shake only when braking from highway speed?

That is typically disc thickness variation from uneven pad deposits or uneven wear on the front rotors. Re-bedding can help mild cases; severe cases need new rotors and pads.

Do I need a scan tool for rear pads?

Yes. The rear calipers use an electronic parking brake that must be opened in lining change mode with a diagnostic tool before the pistons can be retracted.

Sources

1. Audi MediaCenter: 20 years, four generations of the Audi RS 6 - C7 ceramic brakes 420 mm front and 365 mm rear; RS 7 filled the RS 6 role in the US
2. Paragon Brakes: C7 RS6 / RS7 2-piece front rotors - 390 mm by 36 mm front rotor, 34 mm minimum, 0.03 mm run-out on floating design
3. GiroDisc: Audi C7 RS6, RS7 front rotors - fits iron-brake cars, aluminum hats with replaceable iron rings, 34 mm minimum
4. EBC Brakes: Brake squeal causes and cures - squeal causes, creep noise, rotor lips, corroded slides, 5 to 7 year caliper service
5. Ross-Tech Wiki: Audi A6 (4G/4H) parking brake - EPB lining change mode procedure and warnings