2015-2020 Audi RS3 Brake Noise: Squeal, Grinding and Pulsation Causes

By Core Brake Parts Tech Team — Circleville, OH warehouse

Most brake noise on a 2015-2020 Audi RS3 (8V) comes from four places: pads that have not bedded in or lost their shims, corroded or dragging pad hardware, material deposits and thickness variation on the big 370 mm front rotors, and rust on the hub face that makes a new rotor run out. A squeal usually points at pads and hardware, grinding at worn-through pads or debris, and a pulsing pedal at rotor thickness variation. Here is how to tell which one you have and what fixes it.

How the RS3 8V Brake System Is Built

The 8V RS3 was sold as a Sportback from 2015 and as the sedan from mid-2017, which is the body style most North American owners have. On steel-brake cars the front axle uses 370 mm by 34 mm ventilated rotors clamped by fixed eight-piston Brembo calipers. The rear uses a single-piston sliding caliper on a steel rotor, and that rear caliper houses the electronic parking brake motor. Audi also offered an optional carbon ceramic front package with a larger 380 mm by 38 mm rotor and a six-piston monoblock caliper; there is no factory ceramic option at the rear.

This matters for diagnosis. The front fixed calipers have no slide pins, so front noise is almost always about the pads, the pad hardware or the rotor surface. The rear sliding caliper does have pins, and it is the usual place for drag and heat to start. Sedan and Sportback front rotors are not interchangeable in the aftermarket, so confirm the body style before you order.

Squeal: Pads, Shims and Bedding

A high-pitched squeal is the most common complaint, and it can happen with any pad brand on almost any car. EBC's own guidance is that squeal typically shows up in the first 200 to 500 miles on new pads and usually fades as the pads and rotors bed together. If it continues past 500 miles, a series of firm stops on a safe, empty road often finishes the bedding process.

Before blaming the pads, check the basics:

• Shims present: Every pad should go in with its noise shims. A pad installed without them, or with the old shims reused and delaminated, will ring.
• Old rotors with a lip: Fitting new pads to a used rotor with a raised outer edge or an uneven surface stretches the noisy period out, because the new pad only touches part of the face.
• Glazed pads: A pad that has been cooked has a shiny, hard surface that squeals and grabs poorly. Replace it and address the heat source.

Low groaning when you creep off the brake from a stop is a different noise from squeal. It comes from the pad material itself and is harder to cure; it is usually not a fault.

Grinding: Worn-Out Pads, Debris and Rear Drag

Grinding is the noise not to ignore. A metal-on-metal grind means a pad has worn to its backing plate and is cutting the rotor, and at that point both the pad and the rotor on that axle need replacing. A sharp, scraping grind that comes and goes can also be a stone trapped between the rotor and the dust shield.

On the RS3, look hard at the rear axle. Caliper slider pins corrode over time and let the pads drag, which builds heat, glazes the pads and causes both squeal and accelerated wear. EBC recommends servicing or replacing calipers every 5 to 7 years for this reason. With the electronic parking brake, the rear caliper piston has to be retracted through a diagnostic scan tool before new pads will fit; forcing it back by hand can damage the motor.

For pad hardware, clips and pins, see our brake hardware kits, and our brake calipers collection if a caliper is seized.

Pulsation: Disc Thickness Variation, Not Warping

A pedal that pulses or a steering wheel that shakes under braking is usually called warped rotors, but the real cause is almost always disc thickness variation. Wagner explains the chain: lateral runout lets the rotor wobble, the pad lightly contacts the high spot every revolution with the brakes off, and over thousands of miles that wears thin spots into the rotor (or, with ceramic pads, transfers pad material onto it). When those uneven spots pass through the caliper under braking, they push the pistons in and out and you feel it in the pedal.

Wagner notes that most vehicles call for lateral runout of two thousandths of an inch or less, and that the main cause of runout is rust on the hub face where the rotor seats. Ferodo lists the other triggers: dirt between hub and rotor, excessive wheel-bolt torque, a distorted hub, badly centered alloy wheels, seized calipers, and severe overheating. Blue spots on the rotor face mean it has been overheated and should be replaced along with the pads.

On a car with 370 mm front rotors and eight pistons per side, small thickness variations are easy to feel. The fix is to measure before you buy parts:

1. Clean the hub face to bare, rust-free metal before fitting any rotor.
2. Mount the rotor, snug all wheel bolts evenly, and check runout with a dial indicator against the factory specification.
3. Measure thickness at several points around the rotor with a micrometer. If it varies, or the rotor is at the minimum thickness marked on it, replace it.
4. Bed the new pads in gently. Ferodo advises avoiding hard braking for the first 200 km (125 miles).
5. Torque the wheel bolts to the value in the factory service manual, in a star pattern, with a torque wrench rather than an impact gun.

EBC notes that a used cast iron rotor machined on an on-car lathe can perform as well as a new one, as long as it stays above minimum thickness. On the RS3, whose large front rotors are costly to replace, that is worth asking your shop about when the thickness allows.

The Fix and What to Replace Together

Always replace pads and rotors in axle sets, left and right together. If the front rotors are below minimum thickness, grooved, heat-spotted or showing thickness variation, fit new rotors with new pads and new hardware. Our brake rotors and brake pads collections list parts by fitment. Owners who track the car or want lower rotating mass can look at the EBC Racing SG 2-piece floating front rotors for the 2015-2020 RS3 saloon, a two-piece floating design for the sedan.

At the same time, replace the pad shims and clips, clean and lubricate the pad contact points with a brake-specific high-temperature lubricant (never on the friction surface), service the rear slide pins, and consider a fluid flush with the fluid specified on the reservoir cap and in the owner's manual. Old fluid does not cause noise, but a flush is cheap insurance when the calipers are already off.

Carbon ceramic cars are a separate case: their pads and rotors are specific to that system and steel parts will not fit.

How Hard Is the Job?

A front pad and rotor job on the RS3 is within reach of a careful home mechanic with a torque wrench, a dial indicator, and care around the large calipers. The fixed front calipers make pad swaps simpler than a sliding design. The rear is harder only because of the electronic parking brake, which needs a scan tool to open and close the caliper. If a pulsation returns within a few thousand miles of new rotors, the cause is almost always hub rust or wheel-bolt torque, not the parts, so fix the fitment rather than buying rotors again.

Frequently Asked Questions

Why do my new RS3 brake pads squeal?

New pads commonly squeal during bedding, typically within the first 200 to 500 miles. Check that shims were fitted and the rotors were not lipped. If the noise persists past 500 miles, a set of firm stops on a safe road often clears it.

Are my RS3 rotors warped if the steering wheel shakes when braking?

Almost never truly warped. The cause is disc thickness variation, which starts with lateral runout, usually from rust on the hub face or uneven wheel-bolt torque. Measure runout and thickness before replacing parts.

Do sedan and Sportback RS3 front rotors interchange?

Not in the aftermarket. Rotors built for the 8V sedan are listed as not fitting the 8V Sportback, so order by exact body style.

Can I push back the rear caliper piston by hand?

No. The rear caliper contains the electronic parking brake, and the piston must be retracted with a diagnostic scan tool in service mode before fitting new pads.

Can I fit steel rotors to a ceramic-brake RS3?

Not as a direct swap. The optional ceramic system uses a larger rotor and a six-piston caliper, so steel parts built for the eight-piston system will not fit.

What is the grinding noise from my RS3 brakes?

Usually pads worn to the backing plate, a stone behind the rotor, or a dragging rear caliper. Inspect immediately, since worn-through pads damage the rotor quickly.

Sources

1. EBC Brakes - Brake Squeal Causes and Cures - squeal in the first 200-500 miles, shims, slider pin corrosion, 5-7 year caliper service, rotor machining
2. Wagner Brake - Brake Pedal Pulsation and Disc Thickness Variation - runout to thickness variation chain, two-thousandths runout spec, hub rust as main cause
3. Ferodo - Tech Tips for Brake Judder - judder causes, blue spots, 200 km (125 mile) bedding advice
4. Alcon Kits - RS3 8V Sedan Front Rotors - 370 x 34 mm front rotor size, sedan-only fitment
5. DBA RS3 8V Sedan Front Discs listing - factory Brembo eight-piston calipers, sedan from 06/2017
6. ForzaCCB - RS3 8V and 8Y Brake Fitment Specifications - optional 380 x 38 mm ceramic front, single-piston rear with electronic parking brake