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Audi Rear Brake Pad and Disc Replacement
 
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Pelican Technical Article:

Audi Rear Brake Pad and Disc Replacement

Peter Bodensteiner

Time:

1 1/2 hours

Tab:

$100

Talent:

***

Tools:

7mm Allen wrench, brake pad retraction tool

Applicable Models:

Audi A4 (1997-01)
Audi A4 Quattro (1997-01)
Audi TT (2000-04)
Audi TT Quattro (2000-04)

Parts Required:

New brake pads

Hot Tip:

Make sure car is supported correctly on jackstands

Performance Gain:

Better braking

Complementary Modification:

Flush brake fluid

Replacing the rear brake pads on the A4 is roughly similar to replacing the front pads. Rear pads tend to wear more slowly than front pads, which means they may need to be changed less frequently. 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 pads with full-thickness, new pads. 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. I found this difficult to do without a special tool. Of course there is an official, factory approved special tool, but less expensive alternatives can be found. Some claim that you can retract the piston by hand with the right combination of pushing and turning, but I was unable to make this solution work. In the end, I recommend getting your hands on the tool that is designed for the job, as it makes the procedure easy and simple.

You'll need to have the rear of the car off the ground, or at least the corner you're working on. Loosen your lug nuts first and then jack the wheel up and off the ground. Remove the wheel and you're ready to go.

PLEASE NOTE: This article shows the Quattro rear brake discs. FWD rear discs have press-fit rear wheel bearings. You must replace or transfer the bearings if you need to replace the disc rotor. It may be less costly and certainly faster to complete the job if you buy both new rotors and bearings and have the races pressed into the disc rotors before starting the work.

I'll cover adjusting the parking brake first.
Figure 1

I'll cover adjusting the parking brake first. Some sources claim that you must do this as part of replacing the rear brake pads, while others do not. It's not hard to do, particularly in a Quattro, and it's something you may want to do independently anyway, so I've included it here. The first step is to lower your parking brake handle and then go inside the rear seating area of the car. Open the ashtray on top of the center tunnel and lift straight up to remove the ashtray and cover as one unit.

This gives you access to the parking brake mechanism.
Figure 2

This gives you access to the parking brake mechanism. The red arrow points to the "compensator mechanism," which has a series of small holes in it. Take a small screwdriver or a similar tool and push it through one of the holes on the mechanism.

The screwdriver will hold the compensator mechanism in place as you adjust the parking brake cables.
Figure 3

The screwdriver will hold the compensator mechanism in place as you adjust the parking brake cables. Just remember to remove the screwdriver when the job is done and before you start yanking on the parking brake handle.

On the Quattro, the adjusters for the parking brake are outboard, just ahead of the rear wheels and just inside of the side sills of the car.
Figure 4

On the Quattro, the adjusters for the parking brake are outboard, just ahead of the rear wheels and just inside of the side sills of the car. On FWD cars, the adjusters are under the center-rear of the car, in the tunnel that accommodates rear drivetrain parts in the Quattro models. You'll need to get the car up in the air enough to work underneath--make sure to support it properly. See jacking up the car for more information. Once you've located the parking brake adjuster, you first need to remove this metal clip. Needle-nose pliers or a flat-blade screwdriver should do the job.

Use an 11mm wrench to hold the cable at the hex flats on the end of the adjuster.
Figure 5

Use an 11mm wrench to hold the cable at the hex flats on the end of the adjuster. Grab the black portion of the adjuster (it is the piece with the narrow ridges on one end. Turn it so that it moves gradually toward the front of the car. You can turn this by hand.

Eventually the adjuster will move enough that this red O-ring will appear.
Figure 6

Eventually the adjuster will move enough that this red O-ring will appear. You don't want to go further than this, as it will expose the inside of the adjuster to dirt and water, i.e., the things the O-ring is designed to keep out. Back the adjuster out the opposite way until the O-ring is no longer visible.

Re-insert the metal clip into the same groove from which it came.
Figure 7

Re-insert the metal clip into the same groove from which it came.

Turning to the rear brake itself, this is what you'll see once you remove the wheel.
Figure 8

Turning to the rear brake itself, this is what you'll see once you remove the wheel.

The caliper is held to the caliper mounting bracket with two bolts.
Figure 9

The caliper is held to the caliper mounting bracket with two bolts. Actually, the bolts thread into the ends of caliper slider pins, which themselves can be removed. Use a 13mm socket or wrench on the end of the bolt and hold the slider pin in place using a 15mm wrench placed on the flats between the tab on the caliper and the rubber boot, as shown.

Same thing on the bottom bolt.
Figure 10

Same thing on the bottom bolt. It's a little harder to get at the 13mm bolt with a socket and ratchet on this one because of the parking brake mechanism on the back of the caliper.

This is what the bolts that thread into the slider pins look like.
Figure 11

This is what the bolts that thread into the slider pins look like. Note the blue threadlocker compound on the end of the bolt--the new pads should come with new bolts to replace these bolts. The replacement bolts should have some thread locking compound pre-applied to the bottom threads in a similar manner.

Use a screwdriver and/or other pry bars to work the caliper loose.
Figure 12

Use a screwdriver and/or other pry bars to work the caliper loose. It may take a bit of rocking back and forth to free up the caliper.

When the caliper is free, you should see something like this.
Figure 13

When the caliper is free, you should see something like this.

Simply remove the old pads.
Figure 14

Simply remove the old pads.

The brake rotor rotates independently of the hub.
Figure 15

The brake rotor rotates independently of the hub. In order to keep things aligned, you can thread one of the wheel bolts back through the rotor and into the hub.

Remove the rubber cap concealing the bleeder screw on the back of the caliper.
Figure 16

Remove the rubber cap concealing the bleeder screw on the back of the caliper.

Place an 11mm box-end wrench on the end of the bleed screw, place some tubing over the screw end and connect it to a container to catch the fluid.
Figure 17

Place an 11mm box-end wrench on the end of the bleed screw, place some tubing over the screw end and connect it to a container to catch the fluid. Then loosen the bleed screw. Keep the bleed screw open while retracting the caliper piston - this way any dirty fluid will be removed from the braking system rather being pushed back into the braking system. This will also keep you from causing the brake fluid reservoir under the hood to overflow.

As mentioned earlier, some sources indicate that you can retract the caliper piston by hand using a pair of pliers.
Figure 18

As mentioned earlier, some sources indicate that you can retract the caliper piston by hand using a pair of pliers. You're welcome to try it - insert the tips of the pliers into the two notches in the piston face to give you the grip you need. I was able to rotate the piston using this method, but was not able to apply enough force to the piston to force it to retract.

This is a special caliper piston retractor tool.
Figure 19

This is a special caliper piston retractor tool. The round pad at the left pushes on the piston; the flat, slightly arched piece pushes against the inside of the caliper opposite of the piston as the handle is turned.

The magnetic disc on the left attaches magnetically to the foot of the tool, and the two prongs on its surface fit inside the two notches in the face of the caliper piston.
Figure 20

The magnetic disc on the left attaches magnetically to the foot of the tool, and the two prongs on its surface fit inside the two notches in the face of the caliper piston.

Here the tool is in place, now on the passenger side of the car.
Figure 21

Here the tool is in place, now on the passenger side of the car. While you turn the handle clockwise, the part of the tool between the thumb and forefinger must be turned as well to maintain tension on the piston. Essentially, the foot pushes on the piston while the plate pushes on the "fingers" of the caliper. The pressure going in two directions gradually expands the distance between the piston and the fingers, making room for the new pads. Simply keep going until the piston is retracted all the way. Then tighten the bleed screw back down, remove the tubing, replace the rubber cap, and dispose of the old brake fluid properly.

You should remove the slider pins from the rubber boots in the caliper support bracket to inspect and re-grease them.
Figure 22

You should remove the slider pins from the rubber boots in the caliper support bracket to inspect and re-grease them.

Here one of the slider pins is ready to be reinstalled, with a new coating of grease.
Figure 23

Here one of the slider pins is ready to be reinstalled, with a new coating of grease. The new rear pads are also in place in the background.

Simply insert the slider through the rubber boot.
Figure 24

Simply insert the slider through the rubber boot.

Put the caliper back in place.
Figure 25

Put the caliper back in place. Note that the springs on the new pads need to be underneath the caliper and not poking through the gap.

Replace the two 13mm bolts that thread into the ends of the guide pins.
Figure 26

Replace the two 13mm bolts that thread into the ends of the guide pins.

Remember to use the new bolts supplied with the pads, and tighten them to 26 ft-lbs.
Figure 27

Remember to use the new bolts supplied with the pads, and tighten them to 26 ft-lbs. Hold the pin in place with your 15mm wrench while you tighten the bolts.

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Comments and Suggestions:
Jim Comments: Wife had a right rear flat, ruining the tire with 9000 miles Replaced tire noting that brake pads were worn way down. Replaced both sides with new pads though left side was only HALF WORN. Fronts were still fine.
Clearly that r/r brake had been not releasing all the way. I will replace both discs and pads again.
My question regards wheel bearing? Should those be repalced as well or 2nd question will the difference in milage on the tire cause ABS problems. No light is on? Thank you
December 1, 2016
ChrichardsM6 Comments: This article shows the Quattro rear brake discs. You should mention the FWD rear discs have press-fit rear wheel bearings. You must replace or transfer the bearings if you need to replace the disc rotor. I think it may be less costly and certainly faster to complete the job if you buy both new rotors and bearings and have the races pressed into the disc rotors before starting the work.
November 26, 2015
  Followup from the Pelican Staff: Thanks for the additional info. We appreciate it. I will have the article updated.
- Nick at Pelican Parts
 
ChrichardsM6 Comments: Does it matter which direction you rotate the caliper piston? Some of the tool kits supply 2 threaded rods with left and right handed threads.
November 15, 2015
  Followup from the Pelican Staff: Yes, it depends on the vehicle model. Follow directions for your specific vehicle. - Nick at Pelican Parts  
Dollup Comments: I've changed rear pads, but brakes feel very spongey, is there anything I've missed?
September 19, 2015
  Followup from the Pelican Staff: If you didn't open a brake line, maybe one of the rear calipers is seized. - Nick at Pelican Parts  
Chrichardsm6 Comments: What extra steps and tips might you have for removing the disks rotors? Perhaps you should soak the caliper holder bolts and the disk with penetrating oil prior to the work. It may be difficult to remove these if there is much corrosion. If you cannot hit the disks with a mallet from the inside, a puller may be required.
September 8, 2015
  Followup from the Pelican Staff: Thanks for the input on the article. Good tips. - Nick at Pelican Parts  
Chrichardsm6 Comments: Why would you adjust the parking brake if it works well, even with the thin pads? Answer: The compensator is designed to take the cable slack out as the pads wear. You have to reset it all the way back to nearly exposing the o-ring to have some slack in the cable with new pads. If you don't, you will have the parking brake on when you install the new pads and may have a difficult time installing the calipers.
September 8, 2015
  Followup from the Pelican Staff: Thanks for the additional info and feedback. We appreciate it.
- Nick at Pelican Parts
 
KF Comments: Awesome info and clear pictures to follow.
Are A4 and TT Quattro year 2001 range ecentially the same if not very similar?
June 16, 2015
  Followup from the Pelican Staff: Says it applies to that vehicle:

- Nick at Pelican Parts
 
Anthony Comments: do the rear brakes on a '99 audi a6 avant have one or two sensors? my old brakes have two but the replacement parts I got aftermarket only have one sensor
December 22, 2014
  Followup from the Pelican Staff: If you had two, i would replace them both. Do not omit one, as the warning light will come on. - Nick at Pelican Parts  
Moomba Comments: Cheers for this, the bolts on mine are proving tricky, seems like I'm not the only person struggling with them though. Great, clear photos and concise descriptions - I'll be checking out your site again.
March 5, 2014
  Followup from the Pelican Staff: The bolts can seize pretty good.

Thanks for the feedback. Glad we could help.
- Nick at Pelican Parts
 
Ryno Comments: On the front brakes how do u know if you need the sensor or not
February 11, 2014
  Followup from the Pelican Staff: If the warning light is ON, you need the sensor. Or if it breaks during the repair. - Nick at Pelican Parts  
dave Comments: audi a4t 1997 my lift front brake get heat ?
how comme that getting heat?
October 18, 2013
  Followup from the Pelican Staff: The caliper could be stuck on. Or a restricted brake hose not allowing proper fluid flow, keeping the caliper clamped longer than it should be. - Nick at Pelican Parts  
The Goonie Comments: awesome write up and information.

This is so very helpful, and much appreciated.

Thank you!
June 10, 2013
  Followup from the Pelican Staff: Thanks for the kudos - Nick at Pelican Parts  
Rufus Comments: Great info for the home mechanic...thanks keep up the good work.
February 9, 2013
  Followup from the Pelican Staff: Thanks for the kind words. - Wayne at Pelican Parts  

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