2014-2018 Audi S6 Front vs Rear Brakes: What Wears First and What to Replace

By Core Brake Parts Tech Team — Circleville, OH warehouse

On a 2014-2018 Audi S6, the front brakes almost always wear out first. The front axle carries a 400 mm Brembo six-piston setup that does most of the stopping, while the rear runs smaller 356 mm rotors with calipers that also house the electronic parking brake. Plan on replacing front pads and rotors more often than rears, and treat the rear job differently because it needs a scan tool.

How the S6 brake system is laid out, front and rear

The C7-generation S6 (sold in the US from 2013 through 2018) uses two very different brake designs on each end of the car. Knowing which one you have in front of you is the first step to buying the right parts.

The rotor sizes and minimum thickness figures above come from Brembo's catalogue for the C7 S6, and the OE rotor part numbers are Audi's own, listed for the S6 from 2013 through 2018 on the Base, Premium Plus and Prestige trims. The minimum thickness is also marked on the rotor itself, so you can confirm it on the part in your hand.

One exception: some S6 and S7 cars left the factory with optional carbon-ceramic front discs. Those use different rotors and calipers, and iron replacement rotors and pads for the standard system will not fit them. If your front rotors look matte gray with a non-metallic surface, check with the dealer using your VIN before ordering anything.

Which end wears first, and why

When you brake, weight shifts forward and the front tires do most of the stopping. That is exactly why Audi fits the S6 with a much larger front rotor and a six-piston caliper up front: more pad area and more iron to soak up heat. The trade-off is that the front pads and rotors do more work and wear faster.

In real driving, most S6 owners replace front pads more often than rear pads. That said, do not assume the rears are fine just because the fronts were done recently. The stability control system applies individual rear brakes to keep the car straight, and the rear rotors are much thinner to start with, so there is less material to lose before they reach the 20 mm minimum. Spirited driving and city stop-and-go chew through the fronts; steady highway miles wear everything slowly and evenly.

The only reliable way to know is to measure. Pull each wheel, check pad thickness at both ends of each pad, and use a micrometer on the rotor in several spots. Compare against the minimum marked on the rotor.

Symptoms and how to tell front from rear

• Pad warning light on the dash: the S6 uses electrical pad wear sensors. The warning tells you a pad has reached its limit, but not always which one, so look at all four corners. A sensor that has worn through is a one-time part; replace it with the pads.
• Steering wheel shake under braking: this almost always points to the front rotors, usually uneven pad deposits or thickness variation after heat. Large 400 mm rotors hold a lot of heat, and a hard stop followed by sitting with the pedal held can imprint pad material onto the rotor face.
• Seat or body pulsation with a steady wheel: more often the rears.
• Grinding or scraping: the pad is down to its backing plate. Stop driving it; the rotor is now being cut and will need replacement.
• Parking brake fault message or blinking switch light: a rear-axle problem, often a motor or wiring issue at a rear caliper, or a pad job done without the proper electronic procedure.
• Heavy brake dust: black dust on the front wheels is normal with OE-style pads on this car. Switching to ceramic pads usually cuts it.

The fix: which parts to buy for each end

Front: the Brembo six-piston caliper is a durable fixed design and rarely needs replacement. A front brake job is normally pads, rotors and a new wear sensor. Because the rotor is large and costly to machine, most owners replace rotors at the same time as pads rather than reusing rotors close to the 35 mm minimum. Browse replacement brake rotors and brake pads and match them to the S6 400 mm front system.

Rear: the simplest route is a matched kit. Our Brembo OE rear disc brake kit for the 2014-2018 Audi S6 and S7 pairs coated Brembo PVT rotors with Prime Ceramic pads, so the pad compound and rotor are designed to work together. If you only need pads, see our ceramic brake pads.

Always replace pads in axle sets (both sides of the same axle), and replace rotors in pairs. A new rotor on one side and a worn one on the other can cause a pull.

What to replace at the same time

• Pad wear sensors on any axle that has them. A worn-through sensor keeps the warning light on.
• Pad hardware and anti-rattle clips if they are rusted or bent. A brake hardware kit helps prevent squeal and uneven wear.
• Brake fluid: use the fluid type printed on the reservoir cap and follow the change interval in your maintenance schedule. Old fluid absorbs moisture and its boiling point drops, which matters on a car this fast.
• Rear caliper slide pins and boots: clean and re-grease them with high-temperature brake grease. A sticking slide makes one pad wear far faster than the other.
• Rotor retaining screws if they are seized or stripped.

How hard is the job on each axle?

Front: moderate. The fixed Brembo caliper bolts to the knuckle, and the rotor comes off once the caliper is removed. The main effort is handling a heavy 400 mm rotor and pushing six pistons back evenly without damaging the dust seals. Torque the caliper bolts and wheel bolts to the values in the factory service manual.

Rear: not harder mechanically, but it needs electronics. The rear calipers contain the electric parking brake motors. Before you remove anything, the system must be put into pad-change mode with a scan tool that can talk to the parking brake module (address 53 on Audi's system). Ross-Tech's procedure for the A6/S6 C7 family calls this "Start lining change mode" under Basic Settings, which opens the calipers so the pads can be changed. After reassembly you run "End lining change mode," then cycle the parking brake on and off with the switch while holding the brake pedal to clear the service-mode fault and warning light.

A few rules from that procedure are worth repeating: keep a battery charger connected, never run these basic settings while the brakes are disassembled, and expect a "brake pad replacement mode active" fault code while the system is in service mode. Skipping the electronic step and forcing the piston back can damage the actuator. If you do not have a compatible scan tool, the rear pads are the job to hand to a shop.

Frequently Asked Questions

Do the front and rear brakes on a 2014-2018 Audi S6 use the same pads?

No. The front uses a large pad for the Brembo six-piston caliper and 400 mm rotor, and the rear uses a completely different pad for the rear caliper and 356 mm rotor. Order each axle separately or buy an axle-specific kit.

Can I replace the rear pads on an S6 without a scan tool?

It is not recommended. The rear calipers have electric parking brake motors that must be put into service mode electronically first. Skipping that step risks damaging the actuator and leaves you with a parking brake fault.

Should I replace the rotors every time I replace pads?

Measure first. If the rotor is at or near its minimum thickness (35 mm front, 20 mm rear, also marked on the rotor), or has deep grooves or causes vibration, replace it. On this car most owners do pads and rotors together because the labor is the same.

Will S6 brake parts fit an S7 of the same years?

For the standard iron brake system, the OE front and rear rotor part numbers are listed for both the 2013-2018 S6 and S7, and our Brembo rear kit is listed for both. Always confirm your car does not have the carbon-ceramic option.

Why does my S6 get so much brake dust on the front wheels?

The front brakes do most of the work, and factory-style pads are built for strong bite rather than low dust. Ceramic pads made for this system usually produce noticeably less dust.

Sources

1. Brembo catalogue: Audi A6 C7 S6 quattro pads and discs - front 400 x 38 mm (min 35 mm) with Brembo six-piston calipers, rear 356 x 22 mm (min 20 mm), front pad dimensions and rear pad notes
2. Genuine Audi rear rotor 4H0615601P - 356 mm rear rotor, fits 2013-2018 S6 and S7, cross-reference part numbers
3. Genuine Audi front rotor 4H0615301AL - front rotor fitment for 2013-2018 S6 and S7, cross-reference part numbers
4. Audi S6/S7 C7 OEM Brembo six-piston caliper and 400 mm disc reference - 400 x 38 mm disc part numbers, iron vs carbon-ceramic versions, six-piston calipers
5. Ross-Tech Wiki: Audi A6 (4G/4H) Parking Brake - rear pad change mode procedure, module 53, warnings and service fault code