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2005 Audi A6 C6 Brake Discs Replacement (Pictures)

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2005 Audi A6 C6 Brake Discs Replacement (Pictures)

 
Old 10-23-2017, 05:39 AM
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Default 2005 Audi A6 C6 Front Brake Discs Replacement (Pictures)

My front brake discs were worn and braking feel at high speed started to lose quality. My brake pads got worn too recently and needed to be changed so I decided to also change the brake discs while I'm at it. It is recommended to change your brake rotors along with new brake pads.

The parts you need:
- 2 Brake rotors: 4F0615301E
- 2 Front brake pads sets: 4F0698151D
- 2 Brake disc securing T-30 screws: N 10648301
- 4 Brake caliper mount 21mm bolts: N 90876802

The tools you need:
- Penetrating oil
- Anti-seize compound (Read comments for more info)
- T-30 screwdriver
- Bearing pulling tool (at least 33cm wide when spread)
- 21mm (torque) wrench
- Caliper piston compressor tool
- 3/8" Drive 7mm Hex Bit Socket
- Flat head screwdriver
- Sand paper
- Sucking tool: Syringe or Baster
- A container for excess brake fluid
- Sand paper

Difficulty level: Medium

The time it will take you: Half a day or less if you have all the necessary tools

It's not a bad idea to make sure of the size of your brake disc before ordering.






Once you have all the parts and tools, jack-up the car and remove the wheel.




Turn the ignition on and turn the wheels to the opposite side of the side you are working on. I started with the driver's (left) side so I turned the wheels to the right.
Turn the ignition off and remove the key to lock the wheels.




Inspect the hardware





IMPORTANT NOTE 1 - REMOVING THE BRAKE CALIPER: Follow the instructions in my other thread to remove the brake caliper: https://www.audiworld.com/forums/a6-...tures-2900416/


Brake caliper removed. Showing the brake caliper mount securing bolts (2).




Now you need penetrating oil.




Apply penetrating oil at the base of each brake caliper mount bolt. The bolts have a thick washer so make sure you apply the oil at the base.




With a hammer, gently tap about 20 times on each bolt to encourage penetration and separation




You need a 21mm wrench to remove the brake caliper mount bolts




To unbolt on this side, I have to push down. To avoid falling down and causing damage to my hands, I used a hammer with plastic ends to apply force.
On the other side, you will have to pull up which is easier and won't require a hammer's help.




Unlike in this picture, do not use the hammer alone. Hold the other side of the wrench with your left hand to prevent the wrench from bouncing back to your face.
I had to use my left hand to take the picture, that's why you are not seeing it




Use your hand to remove the bolts once they are loose enough.




The brake caliper mount is off.







Time to remove your brake disc Torx screw




Use a T-30 to remove it




Brake disc securing Torx screw removed




If your brake disc was not removed for a long time, it has a big chance to have seized with the mount. Mine was never replaced. 12 years!!!
Use a bearing pulling tool to pull it off.




Disc off.




Here is a video I recorded while doing the other side. In this video I forgot to remove the T-30 brake disc securing screw so it broke. I noticed only later when trying to place the new rotor. I had to have the broken bolt drilled out which wasted my day. I did not have a drilling tool and all the shops were closed yesterday Sunday. It took me hours to find one to borrow and god that screw is tough!

Lesson learned: Always use a checklist and follow it carefully


Here is the video



Showing the brake disc mount.




Clean up the brake disc mount. Use sand paper to scratch off any debris if necessary.




Showing OLD vs NEW discs, bolts and screws




Time to place the new disc. Apply anti-seize to the disc mount. Edit: Seems like anti-seize is not needed here. Check the comments!




Anti-seize applied. Edit: Seems like anti-seize is not needed here. Check the comments!




Place the new disc on the mount.




Apply anti-seize to the new disc securing screw and place it. I did not have a torque tool so I screwed it in just well enough.
Edit: Seems like anti-seize is not needed here. Check the comments!







Apply anti-seize to the new caliper mount bolts. Edit: Seems like anti-seize is not needed here. Check the comments!




Install the caliper mount. Start installing the new bolts with your hand, then tighten with the 21mm wrench. I did not have a torque tool so I bolted them in just well enough.




Installing bolts with hand.




Tightening with wrench.




Brake caliper mount installed.



IMPORTANT NOTE 2 - INSTALLING THE BRAKE CALIPER: Follow the instructions in my other thread to install the brake caliper: https://www.audiworld.com/forums/a6-...tures-2900416/


Showing OLD vs NEW brake pads.




Showing new brake pads inserted in caliper on the side (See important note 2 above for detailed instructions).




Showing caliper securing bolts (See important note 2 above for detailed instructions).
Edit: Seems like anti-seize is not needed here. Check the comments!




Brake caliper installed (See important note 2 above for detailed instructions).







It's good to have a backup ride, just in case




Install the wheel.




Wheel installed.




ONE SIDE IS DONE!
Now move onto the other side and repeat the same steps.












Once complete, insert your key, turn the ignition on, position the wheels straight, turn the ignition off and remove the key. Place the wheel, depress your brake pedal several times, test your electronic parking brakes, adjust your brake fluid level and go for a test drive. Don't forget to bed in your new rotors and pads. The first week, try not to brake too hard and keep a more than safe distance away from the car in front of you.

Drove this morning to work, brakes are working great.

Resources used:

Last edited by kelisko; 12-06-2017 at 01:26 AM.
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Old 10-23-2017, 05:39 PM
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Nicely done. Nothing prettier than brand new brake rotors!
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Old 10-23-2017, 11:52 PM
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Originally Posted by 4Driver4 View Post
Nicely done. Nothing prettier than brand new brake rotors!
Thanks!
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Old 10-24-2017, 06:55 AM
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Great post that should be a sticky on the "How-To" section of the site: https://www.audiworld.com/how-tos/c/brakes-39963/
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Old 10-24-2017, 07:53 AM
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Thank you Kelisko! Great write up!

I actually have all 4 new rotors and pads sitting and need to install them... this is a perfect write up for me and others to follow.

If possible, can someone post the torque rating for all bolts?

Last edited by Nightlifephantom; 10-24-2017 at 07:58 AM.
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Old 10-24-2017, 08:16 AM
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Originally Posted by raj99 View Post
Great post that should be a sticky on the "How-To" section of the site: https://www.audiworld.com/how-tos/c/brakes-39963/
I appreciate. Just checked that page, the rotors replacement section is very vague and rather confusing!
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Old 10-24-2017, 08:27 AM
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Originally Posted by Nightlifephantom View Post
Thank you Kelisko! Great write up!
I actually have all 4 new rotors and pads sitting and need to install them... this is a perfect write up for me and others to follow.
If possible, can someone post the torque rating for all bolts?
Sure! Yes, torque specs would be a great addition. I need to invest in precision tools (torque wrenches). I just don't know where to start. If somebody knows how and where to find good ones with adapters that are flexible and usable with existing bits, please share.

Off-topic message to you: I was in Germany last week. I purchased my discs and pads at one of Frankfurt Audi dealerships. Rather expensive compared to ECS. I also purchased a used side mirror glass on eBay-de. 89.85 euros delivered the next day to my hotel room. So my driver's side mirror glass is fine now. Thanks for your help.

Last edited by kelisko; 10-25-2017 at 12:33 AM.
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Old 10-24-2017, 10:46 PM
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Nice write-up and pics. Here the specified tightening torque values for both type of brakes used on the C6 A6:
* 321 mm disc (FN3):
Caliper Ribbed Bolts: 190 N-m
Guide Pins: 30 N-m
* 347 mm disc (FNRG60)
Caliper Ribbed Bolts: 196 N-m
Guide Pins: 30 N-m

Some comments/suggestions on your write-up for consideration. These comments are based on my experience performing brake R&R service on the (7) VAG cars I have owned over the years.
Removing the Disc/Rotor
If you are replacing the brake disc/rotor, you really don't need a puller to remove it. You can knock it off by striking the back side of the rotor using a ball peen hammer (or similar tool) and rotating it as you strike it. The disc/rotor will eventually pop right off the hub.

Tightening Bolts
Per the Bentley Repair Manual, all torque values are based on dry bolt threads. If you add an anti-seize compound (which is not necessary), you should reduce the installation torque because the compound acts a a thread lubricate. Tightening a bolt to the specified torque value for a lubricated bolt might actually break it because the preload will be greater than the same bolt with dry threads. Also, the green on the caliper ribbed bolt threads shown in your photo is the OEM material than actually acts as an anti-seize compound for these bolts.

Anti-Seize on the Hub Interfacing Surface
Although applying this compound to the surface might eliminate the sticking of the rotor to the hub the next replacement, it might actually cause another issue because it will attract dirt and brake dust. When I have replaced rotors, I wire brush the hub surface clean and leave dry. On the next rotor replacement, I just knock the old rotor off as I indicated above.

Last edited by A6Gary; 10-28-2017 at 10:37 AM. Reason: Correct rotor size for each brake type
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Old 10-25-2017, 12:31 AM
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Originally Posted by A6Gary View Post
Nice write-up and pics. Here the specified tightening torque values for both type of brakes used on the C6 A6:
* 314 mm disc (FN3):
Caliper Ribbed Bolts: 190 N-m
Guide Pins: 30 N-m
* 321 mm disc (FNRG60)
Caliper Ribbed Bolts: 196 N-m
Guide Pins: 30 N-m

Some comments/suggestions on your write-up for consideration. These comments are based on my experience performing brake R&R service on the (7) VAG cars I have owned over the years.
Removing the Disc/Rotor
If you are replacing the brake disc/rotor, you really don't need a puller to remove it. You can knock it off by striking the back side of the rotor using a ball peen hammer (or similar tool) and rotating it as you strike it. The disc/rotor will eventually pop right off the hub.

Tightening Bolts
Per the Bentley Repair Manual, all torque values are based on dry bolt threads. If you add an anti-seize compound (which is not necessary), you should reduce the installation torque because the compound acts a a thread lubricate. Tightening a bolt to the specified torque value for a lubricated bolt might actually break it because the preload will be greater than the same bolt with dry threads. Also, the green on the caliper ribbed bolt threads shown in your photo is the OEM material than actually acts as an anti-seize compound for these bolts.

Anti-Seize on the Hub Interfacing Surface
Although applying this compound to the surface might eliminate the sticking of the rotor to the hub the next replacement, it might actually cause another issue because it will attract dirt and brake dust. When I have replaced rotors, I wire brush the hub surface clean and leave dry. On the next rotor replacement, I just knock the old rotor off as I indicated above.
Gary, great addition! These are good points. I will definitely take them into consideration next time. But I have a few concerns.

Torque specs: If I am not mistaken, the caliper ribbed bolts are the thin ones used to secure the caliper, correct? And the guide pins are what? Need more precision here, please.

Puller: I did not plan to use a puller. I did try the knocking method at first and it did not succeed. I spent about 15min knocking and twisting to no avail. Then I remembered I had the puller which I eventually used.

Anti-seize: I never thought the use of anti-seize could impact the torque load! So what's the recommendation here? Not to use anti-seize at all?
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Old 10-25-2017, 10:57 PM
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Torque Specs
The caliper ribbed bolts (called a combi bolt in the ETKA) are a M14 x 1.5 x 38 bolt. The ribbed "washer" on the bolt head is thin, but that doesn't really matter. What matters is the material strength (or grade) of the bolt. The installation torque of 190 N-m (140 lb-ft) develops an approximate preload of 15,270 lbs, using a 0.2 friction factor for dry threads. For the M14 x 1.5 thread, the tensile area is 116.13 mm^2 (0.18 sq inch). With this preload, the tensile stress is 84,833 psi, which means that the material yield strength must be at least 100,000 psi to prevent yielding of the material. If the threads are lubricated, such as with the anti-seize compound, the friction factor would be less. For example, if the factor dropped to 0.15, the preload would then be 20,360 lbs and the resultant tensile stress would be 113,100 psi, which is greater the assumed yield strength of 100,000 psi. When you exceed the yield strength, the bolt material stretches (yields) and can lead to failure if it strains to the ultimate strength. This example is the reason why one should follow the OEM torque values when tightening fasteners on a vehicle, especially since the typical user has no knowledge of either the bolt material or the deign loads for the joint. The guide pins are not as critical, hence they have a very low installation torque.

Anti-Seize
As I note in the above example, you shouldn't use anti-seize or any other lubrication on high strength bolts unless the OEM specifies the bolts to be lubricated. For comparison, the crank bolt that secures the timing belt gear on the 2.8L V6 engine is specified to be lubricated, and is a one-time use bolt because the bolt stretches after it is installed. The caliper ribbed bolts are not a one-time use bolt, so they should be installed dry.
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