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'Brake' the Audi Squeal Habit

August 05, 2009

Audi owners may complain of squealing brakes. This Tech Tip describes a procedure for reducing squeal and may be used for both front and rear disc brake systems.

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Service Procedure:
Note: Before proceeding with any of the following steps, check the overall condition of the brakes. Verify that the brake discs and brake pads have not reached their wear limits, and if serviced according to the following procedure, will not reach their wear limits as a result of this procedure.
Warning: Never use compressed air to clean brake dust from a brake system. Use proper eye and respiratory protection devices when servicing brake systems.

Applicable Models:
2003 - 2007 TT
2006 - 2007 A3
1996 - 2007 A4
1998 - 2007 A6
All A8
Q7 1997 - 2007

Required Materials:
Plastilube Moly3 or suitable equivalent
Brake Disc Cleaning:
1. With the wheels removed, mark the position of each brake disc in relation to the hub so that the brake discs can be reinstalled in the same position. Work on one brake at a time to avoid mixing up parts.

2. Using a power disc-type sander with an 80-grit sanding disc, clean both sides of the removed brake disc (see Figure 1).

3. This should result in a crosshatch pattern (see Figure 2).

4. Lightly sand the brake disc in a clockwise direction using the leading edge of the sanding disc. Then, continue sanding in a clockwise direction using the trailing edge of the sanding disc.

Brake Pad Cleaning:
1. Some front/rear brake pads may have an adhesive (sticky) backing, which helps adhere the brake pad to the brake caliper. If the vehicle is equipped with this type of a pad, remove this sticky backing and any residual adhesive from the backing plate of the brake pad and brake caliper. Some front/rear brake pads have an anti-vibration backing plate (non-sticky). Do not remove this type of backing.

2. Clean the face of the pad with sandpaper (see Figure 3).

3. Slightly chamfer edges with a file (see Figure 4).

Brake Caliper, Cleaning:
Note: The following steps require a thin coat of Plastilube Moly3 (or suitable equivalent) high-temperature brake grease to be applied to various areas of the brake components. This grease must never come in contact with the brake friction surfaces of the pads or discs.

1. Thoroughly clean all contact points where the brake pad backing plate makes contact with the brake caliper and/or the brake carrier (see Figures 5 and 6).

Reassembly:
1. Reinstall the brake discs in their original position. (See Brake Disc Cleaning, Step 1.)

2. Prior to reinstalling the brake pads, apply a thin coat of Plastilube Moly3 (or suitable equivalent) high-temperature brake grease to all contact points (Figure 6) where the brake pad backing plate makes contact with the brake caliper and/or the brake carrier.

3. For brake pads that have springs (common on rear brake pads), apply a thin coat of Plastilube Moly3 high-temperature grease to the springs where they make contact with the brake caliper.

Courtesy of ALLDATA: Ed Dorowski, ALLDATA Editor and Jeff Webster, ALLDATA Technical writer.

Comments (7)

Comment by:
Paul
6/29/2010
11:32 PM

clean the caliper piston and edges where the pad contacts the caliper. put a light film on the piston where the pad contacts the piston and lube the sids of the pads. The noise will be gone and wont return.

Comment by:
Philscbx
11/21/2009
9:05 AM

I think one key item is missing that will solve all your squealing. Simply use the correct SS pad shim that applies pressure to the forward edge of pads first as brakes are applied.

Comment by:
Osa
9/8/2009
4:01 PM

A gradual vibration developed during using brake whiten speed of 80-60Km/hr Mechanical technician said it comes from the waving of the drums grinding made to the drums and brake pads replaced but the same vibration happen again after one week grinding repeated 3 times again with no useful Drums changed to new one the same case happened after the same period (one week) Brake pads used for Hyundai Santa Fe which same as for KIA Sorento Please your advice to solve the problem will be highly appreciated Car made: KIA Model: Sorento Year : 2006

Comment by:
Gary
9/5/2009
9:43 PM

Sorry but the web site is limiting the number of words, please paste this to the previous email (There are 3 parts total).... the vehicle from about 30 to about 5mph, then let off and re-accelerate back to 30. Do this over an over again until your foot gets tired. The more you baby the pads for the next few days the longer the burnish and the better the pads develop (BEEP, D3EA, CofF and other tests have proven an extended burnish works). You can get more info on this procedure at... www.StopBrakeNoise.com Hope this technical information helps and the explanation of why we have brake noise is of benefit.

Comment by:
Gary
9/5/2009
9:41 PM

This was clipped on previous email... every brake service. Stay away from sand paper because as it wears, the grit level changes and different patterns can be created on the same vehicle.) 3. Scrub the rotor clean with soap and water, to demagnetize it and flush off the metal particles still there from the cut or cross hatch. Do not use bathroom or kitchen soap, they contain oils that penetrate the porous surface of the rotor and will contaminate the pads later) 4. To further reduce the tension on the surface during the burnish, apply the OE Approved Silencer Brake Conditioning Treatment to the rotor to "soften" the mating surface and extend the burnish period even further. Note there are many imitations of this product the market, be careful you have the real version as it is the only one approved for brakes. (Note that the application of products to a pads surface (IE, products like BG distributors and others sell), will void all manufactures warrantees and actually cause damage to the bonding agents they are held together with. There have been cases where pads break apart and the pieces lodge themselves in a manor that locks up a caliper. I can assure you OEM's support the position that "anything on the pad only compromises the original design" no matter what an after-market supplier says, just ask one of them.) 5. Apply a "real synthetic" based boundary lubricant, Ceramlub is the product endorsed and sold by Bendix. It is rated at 2800 degrees and has over 50% solids to support the pads during application. Typically, most all brake lubricants on the market are low temperature petroleum or silicone based and have little to zero solids content. They will not last under the extreme pressure and temperature brake pads, rotors and calipers experience 6. Of most importance is the final break in procedure, it must be perform properly. Although you do need to make at least 30 to 50 pedal applications, your do not want to completely STOP the vehicle each time. Just tap the pads and slow the

Comment by:
Gary
9/5/2009
9:37 PM

Gentlemen, There are a lot of comments here, but most honestly miss the true reason we have brake noise. Surface finish of the rotor is essential to create a proper burnish of a new pad, as discussed above, lubricant is also very important. During the initial burnish period, up to the first 500 stops, the pad is heated and cooled and this up and down cures the friction material. If this takes place to quickly, is aggressive and to much heat is involved, the pad get harder than it should be. It's a proven fact the longer, softer and less aggressive the burnish is... the better the pads develops and higher the level of its performance. In the example above, when you have a pad that starts to make noise after it has been on the road for a while it was burnished to quickly, overheated and most importantly, the lubricant used was the wrong one. Unfortunately it is impossible to unharden a pad, so permanently getting rid of brake noise is just not going to happen. Technically, noise is an in result of harmonic vibration (a condition called slip-stick), but it is also true that the softer the pad is (after the burnish) the less harmonic distortion it creates during application of pedal pressure. Therefore, the way to eliminate brake noise is to never have it (harmonic vibration) occur in the first place. You must create a softer pad from the beginning so that it does not get as hard, like wise you need the right lubricant too. Here is the procedure and products needed to accomplish a top brake service.... 1. Cut a used rotor with round brake lathe bits to produce an ultra smooth finish. If measured, the Ra should be 30 to 35 at this point. Note that a new rotor is generally between 45 and 70, so just buying a new one with not give you the proper number. (If using a new one start with step 2) 2. Crosshatch the smooth surface with a tool called the Flexhone for Rotors to create a new Ra between 40 and 42. Anything rougher will be detrimental to the burnish, you must hit these numbers on ever

Comment by:
jim
8/6/2009
9:23 PM

just use bg products anti-brake squeal on pads,apply to new or used problem sloved trust me it works,never grind rotors