cjk

<center><img src="http://pictureposter.audiworld.com/79872/hre_546r_up_close.jpg"></center><p>Previous owner had these brakes installed- Alcon Type B's I think- 4 pot.

So I need new rotors and pads for the front...anyone have any in stock?

Also- opinions on a good street/minor track pad?- I am running Pagid Blues- to aggressive for me I think with the around town-daily driving I do.

Thanks for the input!

ryoung

IMHO, the Pagid Blue is unacceptable for track use, except perhaps for an autocross. If you find that this pad is too aggressive for the street, you have no chance finding a dual-use street/light track pad.

For an excellent and less aggressive street pad, I'd recommend the Pagid RS4-2-1 Black, but don't expect it to survive on track.<ul><li><a href="https://forums.audiworld.com/a8/msgs/81590.phtml">Pad Comparison</a></li></ul>

cjk

...the previous owner had the brakes put on 4 years ago- rotors atleast...maybe I am at the end of the road on those. That is my biggest hoop to jump through next- finding another set of rotors. I email stasis- no reply...

Are the FerodoDS2500 better then the Blue's? Thanks, your input is greatly appreciated!

ryoung

Also, the DS2500 squeals a bit on some cars (though I've never had the problem). I think you'll prefer the Pagid RS4-2-1 Black. For about 1-1/2 year, I ran with the Pagid RS4-2-1 Black in the front and the Pagid Blue in the rear, and I was very pleased with the performance,

BTW: If you go with the Pagid, make sure you don't get the Pagid RS14 Black. This is a track only pad. Also, Ryan is the other brake guy; this is Randy :-)

cjk

I didn't really have any problems with the Blues...I just didn't realize how fast the brake pads, and rotors wear out is all.

I know this isn't probably a concern for you- but out of the pads you like best- which shed the most dust?

More or less- I like the Blues- just didn't realize I needed to replace them so soon. Coming from a Evo which had 14k miles on it- my pads were in great shape.

Thanks again! Randy :P

ryoung

You're right, brake dust isn't really a concern, but both the Pagids and Ferodos are all dusty enough to require regular wheel cleaning. I really couldn't say which is best or worst, they're all pretty bad.

I haven't noticed rapid pad and rotor wear with any of these pads. How are your (OE?) rear pads/rotors holding up? Has your Alcon setup shifted brake bias forward enough that your front brakes are doing more work than they should? Perhaps go thru the brake bias calculations are see what you have. I find I get the best performance with a brake bias of 2.2-2.3, but that requires running grippier pads in the rear even with my larger than stock rear rotor. Combinations that have worked well for me are,

1. Pagid RS4-2-1 Black front / Pagid RS4-2 Blue rear

2. Pagid RS4-2 Blue front / Pagid RS4-4 Orange rear (the combination currently on the car, and it doesn't squeal)

3. Pagid RS4-2 Blue front / Ferodo DS2500 rear (probably the best balanced combination)

I'd prefer the DS2500 in the front, but I can't find a grippier pad for the rear without going to a very aggressive track pad. In any case, if you get the rears doing more work, the rear pads and rotors are lower cost replacements.

kday

Can you elaborate on how to do the bias calculation?

ryoung

This calculator is a modified version downloaded from 2K2S4's site, an S4 forum member's web site. Since then, the link to his site has died (I'm glad I kept a copy of the calculator), and he's changed his user name several times, but I believe he's now mpwolf.

In any case, the calculator is easy to use. Enter piston diameters, rotor diameter, pad friction coefficient, and system pressure. All the items in bold will be calculated.

For caliper piston diameter, check the Stasis web site for the Alcon specs, and the Bentley for the rear caliper. I use 1000 psi for a typical system pressure. There's also a good <a href="http://www.stoptech.com/whitepapers/brakebiasandperformance.htm">Brake Bias Whitepaper</a> on the StopTech site.

Let me know if you have any questions.<ul><li><a href="http://pws.prserv.net/usinet.Young/BrakeBiasCalculator.html">Brake Bias Calculator</a></li></ul>

kday

That's interesting. Running the numbers for my urS4 I get this:

Stock bias = 2.0
- Front: 40/45 mm, 276 mm rotors
- Rear: 43 mm, 269 mm rotors
Big reds + A8 rotors bias = 2.1
- Front: 36/44 mm, 314 mm rotors
- Rear: 43 mm, 269 mm rotors

All assuming identical compound F/R.

The 2.0 factory bias seems too rear-heavy, but I guess this is compensated for by the brake proportioning valve.

I guess the reason the 993TT calipers work so well on this car is the smaller pistons largely compensate for the change in bias due to the larger rotors.

ryoung

Is there a brake proportioning valve? I think Audi's just rely on rotor and caliper piston sizing.

You mention that the 2.0 factory bias seems too rear-heavy, which sounds exactly correct. On track with my S8, a 2.2 brake bias normally feels very good. If I slide the rear around too much on corner exits, the rear tires overheat, and the back end starts getting squirrely under straight line braking. With the overheated rear tires getting greasy under these conditions, the 2.2 bias becomes too rear-heavy.