No matter what position of your vehicle they are, the condition of the brakes on your Audi S4 is critical. Without them, your sport sedan is a liability to yourself and everyone around you. On all cars, the brakes will be larger at the front to prevent the rear of the car from slowing quicker than the front, causing you to lose control. The reduced force applied to them means they will last longer than the fronts but are just as critical to stopping performance. If you're using the Quattro all-wheel-drive system in the snowy conditions it excels in, knowing your brakes are in proper order is a necessity.
Modern disc brakes are cheap, reliable, and easy to maintain. Replacing the pads and rotors is a job you can accomplish with simple hand tools and an afternoon. The rear brakes on the B8 S4 aren't anything special, just bigger versions of what you'd find on a GTI. Follow along with the DIY to understand just what it takes to service your rear brakes.
Audi models and years applicable:
Symptoms of worn B8 Audi S4 rear brakes:
- A grinding coming from the rear, under braking
- Juddering or a vibration coming from the back, under braking
- Deep grooves on the rotor surface
- Dark-colored deposits on the rotor surface
- The vehicle's steering pulling to one side, under braking
The effects of worn brake pads and rotors on the rear won't be as noticeable as the fronts. With that said, they will still make it apparent when they need to be changed. Because the rear brakes are smaller than the front brakes, they will be cheaper to replace.
Don't drive your Audi if you can't change the brakes yourself. The safest action would be to park the car until you can have a qualified technician do the job.
How much will it cost to replace B8 Audi S4 rear brake pads & rotors?
The kit we used in this video will cost you around $160. For that, you get two new rotors from Zimmerman and a set of TRW pads. The set screws can get pretty mangled when you remove them, so grabbing a couple of extras isn't a bad idea, especially when they'll run you around $1 a piece.
However, to retract the electronic parking brake, you need a scan tool capable of talking to the engine computer and telling it to do so. The best scan tool for the job that we offer is the Autel MX808. It will do anything your modern Audi requires for servicing and will run you just about $460. If you're looking for a cheaper option, you're only other choice is the MD808. It isn't as capable as the MX but will still retract your parking brake. This unit will cost you around $300.
How long will it take to replace B8 Audi S4 rear brake pads & rotors?
Replacing the rear pads and rotors on your Audi S4 is very straightforward. Vehicles in areas with prominent road-salt use may have a more challenging time removing parts, but there is very little to remove. With the right tools and parts, the pad and rotor replacement should take you about an hour.
Parts required to replace B8 Audi S4 rear brake pads & rotors:
Tools required to replace B8 Audi S4 rear brake pads & rotors:
- T30 Torx Bit Socket
- 13mm Socket
- 17mm Socket
- 18mm Socket
- 13mm Wrench
- 15mm Wrench
- Torque Wrench
- Hook Pick
- Channel Locks
- Wire Brush
- Scan Tool
Steps required to replace B8 Audi S4 rear brake pads & rotors:
Step 1: Release the parking brake
The high-end scan tool required for this job, like the MX808 we use, can go into the engine computer and retract the electronic parking brake. Turn the ignition on and plug in the scan tool. Select the "service" option, and then select the "EPB" option.
After that, select "Audi," then "automatic selection." Let the tool read the car's computer to get its VIN. Once it has the VIN, select "OK" and then choose your Audi's model year. After that, chose which body style you have and which engine you have.
At the next screen, select "Hot function" and then "Parking Brake." Once you're there, follow the prompts to release the electronic parking brake.
Step 2: Remove the caliper and pads
Jack up the rear of the Audi and remove the lug bolts with a 17mm socket.
Use a 15mm wrench to counter hold the guide pin while using a 13mm socket to remove the guide pin bolts. You may have to use a 13mm wrench for better leverage on the lower guide pin bolt.
Then, pull up on the caliper and wiggle it off of the pads and bracket. Rest the caliper on the suspension arms to keep any strain off of the brake line.
Lastly, slide the old pads out of the caliper bracket. Use a flathead screwdriver to pry them out if you're met with resistance.
Step 3: Replace the rotor
You can't replace the rotor without removing the caliper bracket. To remove the bracket, use an 18mm socket to remove its two mounting bolts.
Remove the bolts and pull the bracket off of the knuckle. Then, use a T30 Torx bit socket to remove the rotor's set screw. At this point, corrosion will likely be holding the rotor to the hub. Hit the rotor face with a hammer to break it free from corrosion, but thread in one of the lug bolts before doing so. The bolt will catch the rotor from falling off of the hub.
Next, use the wire brush to clean the hub of any corrosion. Once cleaned, fit the new rotor and keep it in place with the set screw. Use a T30 Torx bit socket to tighten the screw.
Refit the caliper bracket and thread in its two bolts by hand. Then, use an 18mm socket to torque the bolts to 100Nm plus 90°.
Step 4: Install the new pads and refit the caliper
Remove the old anti-rattle clips from the bracket and pop on the new ones. Then slide the pads into the bracket.
You need to carefully use a pair of channel locks to squeeze the piston back into the caliper before you can fit it over the new pads. Place one jaw on the piston and the other on the small bolt. You will crack the caliper if you put the jaw on any of the plastic surfaces.
With the piston retracted, fit the caliper over the pads and onto the bracket. Thread in the two mounting bolts by hand to avoid any cross-threading, and always place the fatter bolt on top.
Use a 15mm wrench to counter-hold the caliper a 13mm socket or wrench to drive in the bolts. Then use the 13mm socket to torque the bolts to 35Nm.
With the caliper torqued, refit the wheel. Use the 17mm socket to finish driving in the lug bolts after you've threaded them in by hand. Torque them to 89 ft-lbs.
Step 5: Reset the parking brake
You should have left the scan tool hooked up as instructed. Following the last two prompts, turn the ignition on and press "OK." It will then take the parking brake out of service position and learn where the piston needs to sit with the new pads. Follow the next prompt asking you to apply the parking brake, and the job is done.
B8 Audi S4 Rear Brake Torque Specs:
- Audi Caliper Bracket Bolts = 100Nm or 71.4 ft-lbs, of torque plus 90°
- Audi Caliper Mounting Bolts = 35Nm or 26 ft-lbs, of torque
- Audi Lug Bolts = 120Nm or 89 ft-lbs, of torque
That's how you change the rear pads and rotors on your B8 Audi S4. If you don't know how to bleed the brakes but would like to, click here. If you're interested in more DIYs for your Audi, you can visit fcpeuro.com and subscribe to our YouTube channel.
Owner of a flat-six swapped 1998 Impreza 2.5RS and a 1973 Porsche 914. Horizontally opposed views, only.