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Audi A4 Rear Brake Rotor Replacement
 
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Pelican Technical Article:

Audi A4 Rear Brake Rotor Replacement

Steve Vernon

Time:

2 hours2 hrs

Tab:

$20 to $70

Talent:

**

Tools:

13mm wrench or socket, 15mm wrench, caliper piston compressor

Applicable Models:

Audi A4 (2002-05)
Audi A4 Cabriolet (2003-06)

Parts Required:

Brake rotors

Hot Tip:

Check your brake pads when replacing your rotors

Performance Gain:

Better braking

Complementary Modification:

Caliper rebuild, brake disc replacement, install stainless steel brake lines

Like many modern manufacturers, Audi shares components and even platforms across its many model lines. This article is based on one of those shared components but the work may have been performed on a different model than your vehicle. While some fasteners and other hardware types and sizes may be different, all of the information you need to safely complete the project is included in this article. If you have any questions, comments or feedback please contact us using the comment section below or join us on one of the world's best automotive forums for additional assistance.

Replacing the rear brake rotors on the Audi A4 is an easy DIY job. Rear rotors tend to wear more slowly than front rotors, which mean they may need to be changed less frequently. The rear pad does not have a wear sensor on it, so make sure to check the pads and rotors every 10,000 miles. Also, the rear brakes incorporate the parking brake, which is essentially a cable-operated method of squeezing the brake pads against the rotors, as opposed to the primary hydraulic system.

Another difference is in the method used to retract the caliper pistons, which must be done when replacing worn-out rotors with full-thickness, new rotors. In the front, you can simply push the pistons straight back into the caliper. On the rear, the pistons must be pushed and turned at the same time. There are several options available to you here. You can buy the tool (Pelican Parts sells them) or most local auto parts stores have a free or minimal tool rental program.

Remember, brake rotors should only be replaced in pairs. Replace either both front rotors, both rear rotors or all four at a time. The same rule applies to the brake discs that should be checked each time you replace your brake rotors.

Begin by safely raising and supporting your vehicle. Then remove the rear tires. Please see our article on safely raising and supporting your car.

This photo illustrates the rear brake system.
Figure 1

This photo illustrates the rear brake system. You can see the rotor (red arrow) the caliper (green arrow) and the brake pads (yellow arrow, one showing, and one on the other side of the rotor).

You will need to remove the parking brake ball end (red arrow) and cable clip (green arrow).
Figure 2

You will need to remove the parking brake ball end (red arrow) and cable clip (green arrow). This will allow you to remove the cable from the caliper and allow you to remove the caliper from the vehicle.

Release parking brake.
Figure 3

Release parking brake. Begin by pulling the ball end (red arrow) up and out of its mount.

Use a flathead screwdriver and unclip the cable stay (red arrow) from the bracket.
Figure 4

Use a flathead screwdriver and unclip the cable stay (red arrow) from the bracket.

The clip (red arrow) will pry off with moderate pressure.
Figure 5

The clip (red arrow) will pry off with moderate pressure. Do not loose the clip. I like to put it back on the c able for safe keepings once I have removed the cable.

Push the cable (red arrow) back out from the mount (green arrow) and let the cable hang free.
Figure 6

Push the cable (red arrow) back out from the mount (green arrow) and let the cable hang free.

You will need to remove the two 13mm bolts from the caliper (red arrows).
Figure 7

You will need to remove the two 13mm bolts from the caliper (red arrows).

Use a 16mm wrench to counter hold the guide pins (red arrow) while removing the bolts (yellow arrow).
Figure 8

Use a 16mm wrench to counter hold the guide pins (red arrow) while removing the bolts (yellow arrow).

The bolts (red arrow) are micro-encapsulated from Volkswagen and are considered single use only.
Figure 9

The bolts (red arrow) are micro-encapsulated from Volkswagen and are considered single use only.

Pull the caliper (yellow arrow) off from its mount leaving the brake pads (red arrow).
Figure 10

Pull the caliper (yellow arrow) off from its mount leaving the brake pads (red arrow). Depending on the condition of the pads and whether they have anti-squeal backs you may need to use a fair amount of wiggling and force to get them off.

Hang the caliper up out of the way (red arrow) with a bungee cord or piece of rope.
Figure 11

Hang the caliper up out of the way (red arrow) with a bungee cord or piece of rope. Never let the caliper hang by the brake line.

Remove the old pads (red arrows) from their clips (yellow arrows) in the mount.
Figure 12

Remove the old pads (red arrows) from their clips (yellow arrows) in the mount.

Remove and clean the clips (red arrows).
Figure 13

Remove and clean the clips (red arrows). It is a good idea to replace these when changing your pads.

There are two 8mm Allen bolts (red arrows) holding the caliper mount to the hub.
Figure 14

There are two 8mm Allen bolts (red arrows) holding the caliper mount to the hub.

You will probably need a proper 8mm Allen bit and socket to remove the bolts (red arrows).
Figure 15

You will probably need a proper 8mm Allen bit and socket to remove the bolts (red arrows).

With the bolts removed, remove the mounting bracket and clean any rust and debris from it.
Figure 16

With the bolts removed, remove the mounting bracket and clean any rust and debris from it.

Remove the rotor from the hub (red arrow).
Figure 17

Remove the rotor from the hub (red arrow). You may need to give the "hat" of the rotor a couple of whacks with a mallet to free it up. Some rotors may have an Allen screw holding them to the wheel hub but the standard rotor is just held in place by the wheel lug bots and the brakes.

Clean the mounting area of the flange with a wire brush (red arrow) to give you a good clean and flat mounting surface.
Figure 18

Clean the mounting area of the flange with a wire brush (red arrow) to give you a good clean and flat mounting surface.

If your rotors where warn you will need to push the caliper piston back into the caliper to make room for the thicker rotor, especially if you are also installing new pads.
Figure 19

If your rotors where warn you will need to push the caliper piston back into the caliper to make room for the thicker rotor, especially if you are also installing new pads. On the rear caliper, the pistons must be pushed and turned at the same time. There are several options available to you here, but you will need the use of a special caliper piston tool. You can buy the tool (Pelican Parts sells them) or most local auto parts stores have a free or minimal tool rental program. The tool consists of several "pucks" that have pins (red arrows) that sit in the notches (yellow arrows) in the piston. Place the right puck for your piston on top of it.

Install the rest of the tool and slowly compress the piston while it is turning back into the caliper.
Figure 20

Install the rest of the tool and slowly compress the piston while it is turning back into the caliper.

Before you begin compressing the calipers, check your brake fluid reservoir.
Figure 21

Before you begin compressing the calipers, check your brake fluid reservoir. Compressing the caliper piston which will cause brake fluid to travel back up into the reservoir and you need to make sure there is room for it (red arrow). Carefully clean around the reservoir before you open it, as you do not want any dirt or debris getting into it. Be prepared to use a turkey baster of fluid pump to extract some of the brake fluid if necessary. Make sure whatever you use is clean; you do not want any contaminants getting into the fluid. The caliper is now ready to install new pads. Installation is the reverse of removal. You also may want to spray the back of the brake pads with some anti-squeal paste. This paste basically keeps the pads and the pistons glued together and prevent noisy vibration. Some brands of pads may come with anti-squeal pads already attached to the rear surface. Anti-squeal pads can also be purchased separately as sheets that are peeled off and stuck on the rear of the pads. When finished with both sides, press on the brake pedal repeatedly to make sure that the pads and the pistons seat properly. Take care not to push the brake pedal all the way to the floor, as you can actually damage the master cylinder by driving the piston into usually unused portion of the master cylinder and damaging the seals. Also make sure that you top off the master cylinder brake fluid reservoir if necessary. Brake pads typically take between 100 and 200 miles to completely break in. It's typical for braking performance to suffer slightly as the pads begin their wear-in period. Make sure that you avoid any heavy braking during this period.


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Comments and Suggestions:
Tom Comments: A4 B7 2008 2.0T Cab is right hand thread. Hope that helps.
October 30, 2016
  Followup from the Pelican Staff: Thanks for the additional info and feedback. We appreciate it.
- Nick at Pelican Parts
 
tom Comments: I see your wind back took is a left hand thread. On an A4 B6 I read they were clockwise retract right hand thread. They make both tools. Any thoughts? BTW Great Instructable!
October 27, 2016
  Followup from the Pelican Staff: Both tools are available, depending on the caliper retraction rotation. - Nick at Pelican Parts  
JeMa Comments: What are microenapsulated bolts? I called my Audi dealership parts department, who weren't familiar with them. What could happen when I reuse these bolts in my guide pins?

Nice guide here with great photos, by the way.
February 15, 2016
  Followup from the Pelican Staff: That is a fastener with pre-applied threadlocking compound. If reused they may come loose. - Nick at Pelican Parts  

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