Brake Block=Hell of a difference in braking!
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Joined: Mar 2001
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Just a friction fit between the strut tower bar and the nose of the master cylinder.
Frankly, I'm somewhat amazed that the critical dimensions vary so little from car to car, and The Block seems to fit fine for all.
<img src="http://pictureposter.audiworld.com/17157/theblock.jpg">
<img src="http://pictureposter.audiworld.com/17157/theblock.jpg">
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Elder Member
Joined: Mar 2001
Posts: 11,968
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Some suggestions ...
In order of preference,
1. Bleed the brakes very VERY thoroughly. If necessary, take it to the dealer and ask them to bleed the brakes, including the ABS system. It's truly amazing what a few bubbles of air can do to pedal travel.
2. If that fails, consider a more aggressive street pad. Based on <a href="https://forums.audiworld.com/a8/msgs/81590.phtml">This Comparison</a>, I recommend the Ferodo DS2500. Since it has a coefficient of friction ~40% higher than OEM pads, much less pedal effort (and travel) will be required for the same stop, or a much quicker stop is possible with maximum pedal effort.
3. Upgrade the rear rotor with the <a href="https://forums.audiworld.com/a8/msgs/16643.phtml">Stasis S4 kit</a>. Stock brake bias is a bit nose heavy, the slightly larger rear rotor puts brake bias where it should be, with a noticeable improvement in braking once the rears are doing their share of the work.
Hopefully all three won't be necessary to enable ABS activation in a max effort stop on a dry road.<ul><li><a href="https://forums.audiworld.com/a8/msgs/38595.phtml">My 9 Step Ordeal</a></li></ul>
1. Bleed the brakes very VERY thoroughly. If necessary, take it to the dealer and ask them to bleed the brakes, including the ABS system. It's truly amazing what a few bubbles of air can do to pedal travel.
2. If that fails, consider a more aggressive street pad. Based on <a href="https://forums.audiworld.com/a8/msgs/81590.phtml">This Comparison</a>, I recommend the Ferodo DS2500. Since it has a coefficient of friction ~40% higher than OEM pads, much less pedal effort (and travel) will be required for the same stop, or a much quicker stop is possible with maximum pedal effort.
3. Upgrade the rear rotor with the <a href="https://forums.audiworld.com/a8/msgs/16643.phtml">Stasis S4 kit</a>. Stock brake bias is a bit nose heavy, the slightly larger rear rotor puts brake bias where it should be, with a noticeable improvement in braking once the rears are doing their share of the work.
Hopefully all three won't be necessary to enable ABS activation in a max effort stop on a dry road.<ul><li><a href="https://forums.audiworld.com/a8/msgs/38595.phtml">My 9 Step Ordeal</a></li></ul>
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Not unique to the A8/S8, or even Audi's.
Master cylinders are usually mounted to a flexible firewall. A Google "master cylinder" "brace" search results in 250,000 hits!
Here's the solution for <a href="http://evasivemotorsports.com/merchant2/merchant.mvc?Screen=PROD&Store_Code=EM&Product_Cod e=DRIVE-MC-BR">Honda/Acura</a>, another for <a href="http://www.300degree.com/hard_parts/brakebrace/">Porsche</a>, etc etc. This mpg <a href="http://www.driveroadrace.com/driveRR/movies/mov00076.mpg">Video</a> shows the Honda's master cylinder movement. The magnitude of the problem varies from car to car, but almost every car will benefit to some degree from whatever unique mechanical solution is required to keep the master cylinder from moving. You'd think that automakers would have sorted this out by now :-(
The Honda Brace
<img src="http://evasivemotorsports.com/merchant2/graphics/00000001/drive_master_cylinder_brace.jpg">
Here's the solution for <a href="http://evasivemotorsports.com/merchant2/merchant.mvc?Screen=PROD&Store_Code=EM&Product_Cod e=DRIVE-MC-BR">Honda/Acura</a>, another for <a href="http://www.300degree.com/hard_parts/brakebrace/">Porsche</a>, etc etc. This mpg <a href="http://www.driveroadrace.com/driveRR/movies/mov00076.mpg">Video</a> shows the Honda's master cylinder movement. The magnitude of the problem varies from car to car, but almost every car will benefit to some degree from whatever unique mechanical solution is required to keep the master cylinder from moving. You'd think that automakers would have sorted this out by now :-(
The Honda Brace
<img src="http://evasivemotorsports.com/merchant2/graphics/00000001/drive_master_cylinder_brace.jpg">