2006-2009 Audi RS4 Brake Upgrade Options

By Core Brake Parts Tech Team — Circleville, OH warehouse

On a 2006-2009 Audi RS4 there are really only three brake upgrades worth paying for, and they stack in a fixed order: a better pad compound first, then a lighter two-piece rotor, then a full big brake kit if you are running the car on track. The B7 RS4 left the factory with a 365 mm front rotor, so the common "upgrade" is not more clamping hardware but less heat soak and a friction material matched to how you actually drive.

This guide walks through what the car came with, what each upgrade changes, and which parts fit the 2006-2009 cars with cast iron rotors.

What the B7 RS4 came with

The factory front rotor on this car measures 365 mm, a figure confirmed by GiroDisc when it describes its own 380 mm front disc as slightly larger than the OEM rotor at 380 mm versus 365 mm. That is already a large rotor for a road car, which is why most RS4 owners who complain about their brakes are not short of rotor diameter. They are short of fade resistance, or they are dragging around a heavy one-piece casting that takes a long time to shed heat.

One fitment detail matters more than any other on this car: some RS4s were built with cast iron front discs and some with the optional ceramic front package. Every pad set below is catalogued for the cast iron rotor cars. Look at the disc before you order - an iron-rotor pad on a ceramic disc is the wrong material entirely.

It is also worth knowing what is not wrong with the car. A recall query on NHTSA's database for the 2007 RS4 returns two campaigns, both for the passenger frontal air bag inflator and neither touching the brakes. A soft or fading pedal on this chassis is a wear-and-heat problem, not an open defect.

Step one: pick the pad compound, not the pad brand

This is the cheapest change and it moves the pedal more than anything else. EBC publishes three compounds for the RS4 and they are genuinely different materials, not colour options.

Redstuff is the low-dust answer. EBC builds it with aramid fibres such as Twaron and Kevlar instead of steel fibre, which is why the dust washes off a wheel instead of etching the lacquer, and most of the range is approved to the ECE R90 brake safety regulation. EBC also cites a witnessed test at MIRA in the UK where Redstuff shortened a stop from 100 mph by almost 50 feet. It is designed as a passenger car pad and EBC explicitly does not intend it for truck or SUV fitments - not a problem here. Our fitment for this chassis is the EBC Redstuff front set for the 2006-2009 RS4 4.2 with cast iron rotors.

Yellowstuff is the fast-road step up. EBC removed copper from the mix in 2021 to meet environmental legislation, and the reformulated material lasts longer but needs a longer bed-in - which is exactly why EBC no longer suggests it as a track pad for most cars and points track users at Bluestuff instead. EBC is also blunt that these are not low-dust pads. If your RS4 sees hard road driving and the occasional hill run, the Yellowstuff front set is the right call.

Bluestuff NDX is the one to buy if the car sees lapping days. It is the compound EBC itself now points track users toward, on the strength of a much faster bed-in and higher fade resistance than the current Yellowstuff mix - which matters when you are fitting pads the night before an event rather than a month ahead. That is the Bluestuff NDX front set for the 4.2L. More compounds for other platforms sit in our brake pad catalogue.

Step two: two-piece rotors, for unsprung weight and heat

The factory front disc is a single iron casting with the hat and the friction ring in one piece. A two-piece rotor bolts a cast iron friction ring to an aluminium centre hat, which does two things: it drops rotating unsprung mass, and it lets the ring expand without dragging the hat with it.

GiroDisc's front set for the B7 RS4, part A1-100, is a 380 mm disc supplied with the caliper spacers needed to move the factory caliper out to the larger diameter. The hat is US-sourced 6061-T6 aircraft specification aluminium, the ring is cast iron poured and machined in-house, and the two are joined by 12 cadmium-plated alloy steel drive pins secured with class 12.9 cap screws, hardened washers and anti-noise spring washers so the ring can float axially and radially. GiroDisc quotes the pair at approximately 22.6 lbs against 25.5 lbs for the stock units - about 2.9 lbs of rotating unsprung weight gone from the front axle. The internal vanes are a curved design taken from racing, working as a centrifugal pump to force cooling air through the disc.

The rear set, part A2-100, is built the same way - cast iron ring, 6061-T6 hat, curved vanes, axial and radial float - with 10 drive pins instead of 12. Both are on the shelf here: GiroDisc 380 mm zinc plated slotted front rotors with spacers and GiroDisc slotted rear rotors. Plain replacement discs for other cars live in the rotor collection.

One honest note: a two-piece rotor does not increase peak grip - that is set by tyre and pad. What it buys you is consistency across repeated hard stops and less mass for the suspension to control.

Step three: a full big brake kit

A big brake kit replaces the caliper as well as the disc, and that is the only upgrade in this article that changes clamping force and pad area. Brembo builds its GT-family kits around a monobloc caliper machined from a single billet of aluminium cast in Brembo's own foundry, using a casting process that routes the fluid through internal channels rather than external pipework. The discs are two-piece and float on an aluminium alloy bell, which cuts weight and helps the ring dissipate heat; Brembo states the ventilation design raises thermal shock resistance by more than 40 percent, and positions the kits for both road and track use.

For the RS4 the rear kit we carry is the Brembo GT rear big brake kit with 4-piston calipers and 380x28 slotted two-piece rotors in yellow, for 2006-2008 cars. A rear kit is the usual second move on an RS4 that already has strong front brakes, because it rebalances the car under repeated heavy braking rather than piling more capacity on an axle that already has plenty.

What to do at the same time

Whatever you fit, do these three things in the same afternoon, because they are what actually causes a fading pedal:

• Flush the brake fluid. Use the DOT specification printed on your reservoir cap and in the factory service manual. Old fluid absorbs moisture and boils long before a good pad gives up.
• Inspect the flexible hoses. A swollen hose feels exactly like a soft pedal and no pad will fix it. Replacements and stainless lines are in brake lines.
• Replace the hardware. Clips, shims and slider boots are cheap, and a seized guide pin will destroy a new pad on one side. See hardware kits.

Torque every caliper bracket bolt, carrier bolt and wheel bolt to the value in the factory service manual - the RS4's front caliper hardware is not a guess-and-go fastener.

How hard is the job

A pad swap here is a competent home mechanic's afternoon: retaining pins and pad springs out, pads out, clean and lubricate, new pads in, bed them per the compound's instructions. Two-piece rotors with caliper spacers add a step, because the caliper comes off and is re-positioned for the larger disc, and the spacer bolts carry the entire caliper load - they get torqued to spec, not by feel. A full big brake kit also means new hoses or adapters and a complete bleed, which is where most people hand the car to a shop.

Frequently Asked Questions

Will bigger rotors alone make my RS4 stop shorter?

Not on the first stop. Peak stopping distance is limited by tyre grip and pad friction, not rotor diameter. Larger two-piece rotors change how consistent the car is on the fifth and tenth stop, and they take rotating weight off the axle. If you want a shorter single stop, change the pad compound and the tyre.

Which EBC compound should I buy for a street RS4 I never track?

Redstuff if clean wheels and quiet operation matter most, Yellowstuff if you drive hard on the road and accept more dust. EBC states Redstuff uses aramid fibres rather than steel fibre so the dust does not etch wheel finishes, and that Yellowstuff is not a low-dust material.

Can I use Yellowstuff on a track day?

EBC no longer recommends it for most track use, because the reformulated copper-free material needs a longer bed-in and you should not arrive at an event with new Yellowstuff pads. EBC points track users to Bluestuff instead, citing its much faster bed-in and higher fade resistance.

Do the 380 mm rotors need spacers?

The GiroDisc front set ships with caliper spacers, because the factory caliper has to sit further out to reach a 380 mm friction ring instead of the 365 mm original. Fit the supplied spacers; do not try to run the larger disc in the standard caliper position.

How do I know if my car has cast iron or ceramic front discs?

Look through the wheel. A cast iron disc shows the usual grey machined friction face and will surface-rust overnight in the rain; the optional ceramic disc does not rust and is a different material altogether. The pad sets listed here are catalogued for cast iron rotor cars only.

Is there a brake recall on the 2006-2009 RS4?

Not according to NHTSA. A recall query for the 2007 RS4 returns two campaigns, both covering the passenger frontal air bag inflator. Check your own VIN on NHTSA's site, since campaigns are added over time.

Sources

1. GiroDisc - Audi B7 RS4 380mm front rotors - the 365 mm factory rotor size, the 380 mm two-piece construction, 6061-T6 hat, 12 drive pins, curved vanes and the 22.6 lbs versus 25.5 lbs weight figures.
2. GiroDisc - Audi B7 RS4 rear rotors A2-100 - rear two-piece construction, 10 drive pins, class 12.9 hardware and axial and radial float.
3. EBC Brakes - Redstuff ceramic brake pads - aramid fibre construction, no steel fibre, ECE R90 approval, the MIRA stopping distance test and the passenger-car-only application.
4. EBC Brakes - Yellowstuff fast street pads - the 400 C green fade threshold, the 2021 copper-free reformulation, the longer bed-in and EBC's current track guidance.
5. Brembo - GT kit - monobloc caliper construction, two-piece floating discs on an aluminium bell, the 40 percent thermal shock figure and road and track positioning.