Fitting New Rotors on an A8
09-30-2002, 11:27 PM
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Fitting New Rotors on an A8
Hi all, I am new to the A8 and would like some info on fitting rotors to the front. Question 1: how do the calipers come off. Question 2: how do the rotors come off........ Best Regards JOHN
PS) thanks for the info Randy.
PS) thanks for the info Randy.
10-01-2002, 03:57 AM
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On an S8 ...
.
John,
I don't know how different the A8 is from the original S8 Brembo's or my Alcon's, but replacing front rotors on my car is reasonably simple.
1. Remove the brake pads.
2. Remove the caliper (two large hex recess cap screws) and hang the caliper out of the way. Hang it from a piece of twine or a short bungie cord; don't let it hang by the brake lines.
3. You may have to rap the old rotor with a mallet if it's rusted on, but the rotor should now just slide off.
4. Lube the hub with some brake caliper grease (to prevent rusting the rotor to the hub next time) and reverse the above procedure. Also I use a couple drops of blue Loctite on the threads of the cap screws.
5. You'll have to push the caliper pistons back whether you're installing new pads or not. Keep an eye on the brake fluid reservoir when you do this. You're pushing fluid back from the caliper to the reservoir and definitely do not want to overflow it. This is likely to happen if you've topped up the reservoir as the pads wore. If necessary, you can remove excess fluid with a turkey baster, or my method -- use a bit of clear flexible tubing to siphon out the excess.
Hope this helps,
John,
I don't know how different the A8 is from the original S8 Brembo's or my Alcon's, but replacing front rotors on my car is reasonably simple.
1. Remove the brake pads.
2. Remove the caliper (two large hex recess cap screws) and hang the caliper out of the way. Hang it from a piece of twine or a short bungie cord; don't let it hang by the brake lines.
3. You may have to rap the old rotor with a mallet if it's rusted on, but the rotor should now just slide off.
4. Lube the hub with some brake caliper grease (to prevent rusting the rotor to the hub next time) and reverse the above procedure. Also I use a couple drops of blue Loctite on the threads of the cap screws.
5. You'll have to push the caliper pistons back whether you're installing new pads or not. Keep an eye on the brake fluid reservoir when you do this. You're pushing fluid back from the caliper to the reservoir and definitely do not want to overflow it. This is likely to happen if you've topped up the reservoir as the pads wore. If necessary, you can remove excess fluid with a turkey baster, or my method -- use a bit of clear flexible tubing to siphon out the excess.
Hope this helps,
10-01-2002, 05:37 AM
#4
Randy's procedure is close, but the A8 differs a little......
1. Before removing brake pads the caliper/pad assembly must be removed as a unit- see Randy's step #2. Note- the two hex recess screws may be covered with a rubber dust cover. (reinstallation torque is 22 lb.-ft.). Also, be careful of the electrical wear indicator wire that goes to the pad- it is easy to break.
2. Once the caliper/pads are removed, there are two bolts that hold the caliper carrier onto the steering knuckle that must be removed (might be pretty tight- use 1/2 drive breaker bar).
3. Remove the rotor per Randy's step #3- plastic mallet is recommended.
4. Follow the remainder of Randy's instructions, with the addition of reinstalling the caliper carrier after the rotor and before the caliper (get it tight- spec is 140 lb.-ft.!). You may want to use brake grease on the contact portions of the caliper /pad carrier and apply brake-specific RTV behind the brake pads to help eliminate brake squeal (both products available at local parts store- Bendix makes good stuff). One note of caution- if you mouth siphon the brake fluid, be VERY careful- it is poisonous (I use the turkey baster method- my wife hasn't missed it yet)! From Alldata-
"Brake fluid is poisonous. It must never be extracted using suction by mouth through a hose.
If brake fluid contacts skin or eyes, flush or wash adequately to prevent irritation. Get medical attention if necessary."
5. If your brake fluid hasn't been replaced in the last two years, then now would be a good time to do that too. Be sure to use the correct fluid! "Use only fresh brake fluid conforming to US Standard FMVSS 116DOT4. Genuine VW/Audi brake fluid conforms to this specification." A complete flush will require around 2 liters of fluid.
If you take your time and do a good job, expect to spend 30-40 minutes per wheel to complete the job.
2. Once the caliper/pads are removed, there are two bolts that hold the caliper carrier onto the steering knuckle that must be removed (might be pretty tight- use 1/2 drive breaker bar).
3. Remove the rotor per Randy's step #3- plastic mallet is recommended.
4. Follow the remainder of Randy's instructions, with the addition of reinstalling the caliper carrier after the rotor and before the caliper (get it tight- spec is 140 lb.-ft.!). You may want to use brake grease on the contact portions of the caliper /pad carrier and apply brake-specific RTV behind the brake pads to help eliminate brake squeal (both products available at local parts store- Bendix makes good stuff). One note of caution- if you mouth siphon the brake fluid, be VERY careful- it is poisonous (I use the turkey baster method- my wife hasn't missed it yet)! From Alldata-
"Brake fluid is poisonous. It must never be extracted using suction by mouth through a hose.
If brake fluid contacts skin or eyes, flush or wash adequately to prevent irritation. Get medical attention if necessary."
5. If your brake fluid hasn't been replaced in the last two years, then now would be a good time to do that too. Be sure to use the correct fluid! "Use only fresh brake fluid conforming to US Standard FMVSS 116DOT4. Genuine VW/Audi brake fluid conforms to this specification." A complete flush will require around 2 liters of fluid.
If you take your time and do a good job, expect to spend 30-40 minutes per wheel to complete the job.
10-01-2002, 06:17 AM
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Since discretion is the better part of valor ...
.
the turkey baster would be the preferred method.
I use clear tubing to siphon out any excess fluid so that I can see it coming. You're absolutely right, you certainly do not want a mouthfull of brake fluid !!
the turkey baster would be the preferred method.
I use clear tubing to siphon out any excess fluid so that I can see it coming. You're absolutely right, you certainly do not want a mouthfull of brake fluid !!
10-01-2002, 07:46 PM
#7
Re: Just curious - Does anyone know what the lesser part of valor is?
DISCRETION IS THE BETTER PART OF VALOR - Exercise caution, don't take unnecessary risks. Proper judgment is better than unwarranted bravery. The proverb has been traced back to Caxton's `Jason' (c.1477) and was popularized by Shakespeare in `King Henry the Fourth, Part I' (1597-98) and by Beaumont and Fletcher in `A King and No King' (1619). First attested in the United States in Benjamin Franklin's `Poor Richard's Almanac' (1747)..." From the "Random House Dictionary of Popular Proverbs and Sayings" by Gregory Y. Titelman (Random House, New York, 1996).
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10-02-2002, 09:12 AM
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Re: Randy's procedure is close, but the A8 differs a little......
Hi Skiracer, would you hapen to have the torque settings in Newton Meters ie: 22ft/lbs and 140ft/lbs. Also would anyone have a picture or drawing of the position of the Fixing Screws for the calipers?, many thanks to all who help JOHN A84.2
10-02-2002, 05:29 PM
#10
1 lb.-ft. equals 1.356 Newton-meters, so 22 lb-ft=30 N-m and 140 lb-ft=190 N-m
<center><img src="http://pictureposter.audiworld.com/24433/front_brake_diagram.jpg"></center><p>Here is the diagram of the front brakes- item #8 is the brake carrier bracket (#10) hold down bolt (only one is shown, but there are two.) On my car, I had to remove the bracket to remove the disc, but try getting yours off before removing the bracket- it may work.