2012-2016 Audi A5 Brake Noise: Squeal, Grinding and Pulsation Causes

By Core Brake Parts Tech Team — Circleville, OH warehouse

Most brake noise on a 2012-2016 Audi A5 comes from one of a short list of causes: pads or rotors near their wear limit, debris or rust between pad and rotor, contamination on the rotor face, or dry and corroded pad hardware. Grinding usually means metal-on-metal wear or trapped grit, and a pulsating pedal points to uneven rotor thickness. Audi's own service bulletin for these cars walks technicians through exactly that list before any part gets replaced, and it is the right order for owners too.

How the A5 brake system is built

The B8-generation A5 (Audi platform code 8T) uses disc brakes at all four corners, and the rear calipers carry the electro-mechanical parking brake (EPB): a small electric motor on each rear caliper drives the piston to hold the car when parked. That matters for the repair, because the rear pads cannot be serviced like a conventional caliper. The piston has to be retracted electronically with a scan tool first.

Audi fitted different front brake packages depending on engine, drivetrain and model (A5, S5 and RS 5 share the body but not the brakes), and each package is identified by a PR code. Before buying pads or rotors, confirm your front brake option from the PR code on the vehicle data sticker, or measure the rotor on the car. Parts for one package will not fit another.

Squeal, grinding, groaning and pulsation: what each noise means

Audi's technical service bulletin 2034181 ("Brake noise analysis and handling") covers 2013 A5 and S5 coupes from VIN 902741, all 2014 A5 and S5 models, and the matching Cabriolets. It lists the complaints customers report as squeal, squeak, grinding, groaning, thumping or creaking, from the front or rear brakes. Brake-component makers break those sounds down by frequency, which is a practical way to diagnose them:

The seven common causes Audi lists

Before any parts are replaced, the Audi bulletin tells technicians to rule out these seven causes:

1. Pads or rotors close to or below their wear limit. Thin pads and worn rotors lose the mass and damping that keep vibration in check.
2. Non-original pads or rotors already installed. Pads without proper shims and chamfers are a frequent source of squeal. Quality replacement pads with fitted shims avoid the problem.
3. Debris between pad and rotor such as small stones, grit, road salt or sand. This is a classic cause of sudden grinding on a car with plenty of pad left.
4. Rust on the rotors from a car that has sat unused for a long time.
5. Grooved rotors. Deep grooves keep new pads from seating fully.
6. Chemical contamination from wheel or tire cleaner sprayed straight onto the rotor, which leaves discoloration and spotting on the braking surface.
7. Pad marks, where pad material transfers to the rotor when the car is parked for long periods in wet or snowy weather.

For noise not explained by any of those, the bulletin's first step is a cleaning procedure: with careful attention to traffic, make 2 to 5 ABS stops from above 50 mph, driving at least a minute above 50 mph between stops to let the brakes cool, then let the car sit for two hours and test drive again. That scrubs light rust, pad marks and deposits off the rotor face. Only do this where it is legal and safe.

An earlier Audi bulletin for the related S4 and S5 front brakes adds more exclusions worth checking on any B8 car: un-ground or corroded friction material, metallic deposits from the rotor embedded in the pad, and other deposits in the pad surface. The same bulletin notes that Audi began applying anti-seize to the caliper carrier guide pins in production from September 3, 2012, and its repair calls for a thin coat only on the section of the pins the pads touch. Dry, corroded pad guides are a common squeal source on these cars.

How to diagnose the noise on your A5

Start by finding which corner the noise comes from. Audi stresses that knowing the location is critical and suggests an assistant listen from inside or outside the car. Then work through this order:

• Measure the pads. Look through the wheel spokes or pull the wheel. If the friction material is close to the backing plate, the fix is pads, and very likely rotors too.
• Inspect the rotor faces. Look for a lip at the outer edge, deep grooves, blue heat spots, rust bands or dark pad imprints.
• Check the caliper. The pads should move freely in the carrier and the piston should not be sticking. A dragging caliper overheats pads and causes both squeal and uneven rotor wear.
• Check for judder. A pulsation felt in the pedal or steering wheel under braking usually means thickness variation in the front rotors. Rust or dirt on the hub face under the rotor causes runout that develops into the same problem. Ferodo's guidance is that a mounted rotor should stay within 0.1 mm of runout.
• Rear brakes: remember the EPB. Do not lever the rear pads out or force the rear pistons back.

The fix, and which parts to buy

If the pads are worn or the rotors are grooved, lipped or out of tolerance, replace pads and rotors as a set on the axle. Choose pads that come with shims and chamfers, and replace the abutment clips and hardware when they are corroded or weak, since worn clips let pads rattle and vibrate.

• Shop brake pads for your Audi, or go straight to low-dust ceramic brake pads if you want a quiet daily-driver pad.
• Pair them with new replacement brake rotors so the new pads bed into a flat, clean surface.
• Replace tired clips with a brake hardware kit.
• For a firmer street pad on quattro models, the Hawk HPS 5.0 front brake pad set (HB757B.758) is listed for the 2013 A5 quattro. Confirm your front brake package before ordering.

At installation, clean the hub face so the new rotor sits flat, clean corrosion from the pad abutments and caliper piston, and put a light coat of silicone brake lubricant on the back of constrained-layer shims, as Wagner recommends. Then bed the pads in: Wagner's recommended break-in is 20 gradual stops from 50 mph down to 20 mph, which lays an even layer of pad material on the rotor and heads off both squeal and judder.

What to replace at the same time, and how hard the job is

A front brake job on an A5 is a moderate DIY job with basic hand tools, a torque wrench and a caliper piston tool. Torque the caliper carrier bolts, caliper bolts and wheel bolts to the values in the factory service information. While the wheels are off, check the brake hoses for cracks and the brake fluid for age, and use the fluid type printed on the reservoir cap.

The rear brakes are harder because of the EPB. The rear pistons must be retracted in service mode with a scan tool that supports Audi's parking brake module before the pads come out, and the service mode must be closed afterward. Ross-Tech warns that the EPB module is very sensitive to low voltage, so keep a battery charger connected for the whole rear brake job. Forcing a rear piston back without service mode can damage the caliper motor and turn a pad job into a caliper replacement. If you do not have a compatible tool, have a shop do the rears.

Frequently Asked Questions

Why do my A5 brakes squeal only for the first few stops in the morning?

That is usually surface rust or moisture on the rotors, which Audi lists as a common cause. If the noise goes away after a few stops, it is normal. If it continues all day, check pad wear, shims and pad guides.

My A5 brakes grind but the pads look thick. What is it?

Grit, small stones or road salt trapped between the pad and rotor is a common cause Audi names. Pull the wheel and inspect. A deep score in the rotor usually means the rotor needs replacing along with the pads.

What causes a pulsating brake pedal on an Audi A5?

Pulsation (judder) comes from uneven rotor thickness or poor rotor fit on the hub. The fix is new rotors, a clean hub face, correct wheel bolt torque and a proper pad bed-in.

Can I change A5 rear brake pads without a scan tool?

The rear calipers use an electro-mechanical parking brake, so the pistons need to be retracted in service mode with a compatible scan tool. Forcing them back risks damaging the caliper motor.

Will new pads alone stop the noise?

Only if the rotors are still flat, smooth and above minimum thickness. Grooved, lipped or glazed rotors keep new pads from seating, so most quiet brake jobs on these cars include rotors.

Should I spray wheel cleaner on my brakes?

No. Audi specifically lists chemical contamination from wheel or tire cleaner sprayed onto the rotor as a cause of brake noise. Spray the wheel, not the brake.

Sources

1. Audi TSB 2034181, Brake noise analysis and handling (NHTSA) - A5/S5 coverage, seven common noise causes, ABS-stop cleaning procedure
2. Audi TSB 2027636, S4 and S5 front brake squeal (NHTSA) - noise exclusions, anti-seize on guide pins from September 2012 production
3. Ross-Tech Wiki, Working on the Electro-Mechanical Parking Brake - A5/S5 (8T) EPB, service mode, low-voltage warning
4. Ferodo Technical Tips, Brake Noise - squeak, squeal and judder causes, 0.1 mm runout tolerance
5. Wagner Brake, Brake System Noise Troubleshooting - hardware, shim lubrication, 20-stop break-in