[nathansvt]

I put the Porterfield R4S pads on and drove about 300 miles to a track day. I ran 2 days on those pads on a medium-tight course. When I pulled the pads on the second day (forgot to change 'em until I felt griding) The rears were half gone and the fronts were down to the backing plates (ugh).

The rears had perfectly even wear, on each side of the caliper and on each side of the car. The passenger side front was also even wear, down the plates on both sides of the caliper. So I went over to the drivers side and the outboard pad was also on the backing plate. What strikes me as REALLY odd is that the driver side inboard pad still has about 1/4 to 1/3 of the pad left. I bled the caliper to see if it was due to a bubble, but I got clear fluid from both sides. Any thoughts on why this may be happening? I didn't notice any uneven wear when I pulled the factory pads off the first time, at about half-pad.
I would expect uneven wear (on the inboard side) with a floating caliper, but I thought our fixed calipers should reduce the tendency to wear one side more than the other.

poor quality pics here:
http://www.sti-buki.com/forums/showt...=&threadid=248

[timb]

I would have thought bubble, like you. Anyway, how did the RS4's perform?

[FT@SGP]

Hello Nathan,

I saw the post yesterday at NASIOC and read it, but did not have a clear idea of what it might be, so I did not respond. However, I asked someone else who has more experience with brakes, without showing the photographs; and he mentioned that something might be cloging the brake lines, resulting in uneven distribution of fuild across inner/outter calipers. Again, I am no brake expert, so I cannot even judge if that is feasible; but I do trust the person who provided the information.

You might just want to take it to the dealer and get their opinion as well.

[nathansvt]

they were ok. I was happy with their performance but they wore more quickly than the stock pads, which was a bit of a surprise. I'm now running the R4S in the back and Cobb Racing up front. I like the feel of the cobb racing better, and because it never really gets cold here they bite enough for street use, esp with the porterfield in the back. I know I'll get more rotor wear with the cobb racing pads, but since the backing plates scored the rotor a little bit I'm planning a replacement soon anyway. Noise with the porterfields is non-existent. The cobbs squeal a little, but not enough to bother me.

[nathansvt]

Originally Posted by FT@SGP

Hello Nathan,

I saw the post yesterday at NASIOC and read it, but did not have a clear idea of what it might be, so I did not respond. However, I asked someone else who has more experience with brakes, without showing the photographs; and he mentioned that something might be cloging the brake lines, resulting in uneven distribution of fuild across inner/outter calipers. Again, I am no brake expert, so I cannot even judge if that is feasible; but I do trust the person who provided the information.

You might just want to take it to the dealer and get their opinion as well.

That might be correct, although it seems that the problem would then be internal to the caliper. The pistons on both sides run off one incoming brake line. I did re-bleed the caliper and hopefully that will be enough to fix the problem. I'll certainly be checking the wear over the next couple months to keep an eye on it.

[wrcdave]

Install some brake ducts to help cool down the brakes. On a track with short straights the brakes can't cool down enough so they will wear at a much faster rate. Also make sure your using ATE super blue or AP600 brake fluid. Good luck.

[TrackRat]

Hi Nathan SVT,

I have experienced the the same wear paterns in my 65 mustang race car. This car has a similar brake "architecture" when compared to the STi. Both have fixed 4 piston calipers. I usually wear out the left front pad on the Mustang before the others.

Most road courses run in a clockwise direction and consequently have more right turns than left turns. I'd bet the cost of an oil change that the circuit you drove on went in a clockwise direction, or had some monster right hand turns at the end of a braking zone.

As a result of this loading, your left front tire does a large amount of work on these circuits. Since the brake pads are pushed back into the caliper by the action of the rotor (once you release pedal pressure), any flex in this highly stressed left front tire/wheel hub/rotor assembly will cause wear on the outboard pad in particular. The flex can be a result of the normal flexing of the hub or even the axle stub. Something to check would be your front wheel bearings; too loose a bearing set-up would undoubtedly contibute even more to this condition. I believe however, that you bearings are fine- you are just seeing the normal wear and tear of track driving.

You will also see heat "checking" of the rotor first on that same outside face. Checking is the fine array of cracks that usually appear radially on the rotors after you use them "in anger" for a while. As long as they do not connect, you are generally OK. Once these little cracks start to connect and look like a "road map", toss 'em and put on a new set. Correctly "seasoning" rotors and "bedding" pads will give you good, long life to both. You have to consider that rotors and pads, -especially fronts- are a consumable item when track driving.

WRC Dave said to put brake ducts on the car, and I believe that is good advice too. Anything you can do to cool the rotor and pad will help with longevity.

My Mustang is an old Canadian Touring car and has the stock Kelsey Hayes 4 piston calipers and relatively small stock rotors that were used in 1965. This car is significantly "underbraked" compared to the massive binders on the STi. As a consequence, I see the limits of brake fluid, pads and rotors much earlier on this car.

I have a March Date with my STi at lime Rock. This will be my first track outing with the STi. I am going to put on Porterfield R-4 pads (not R-4S pads) bleed with Motul and give it a whirl.

Yours in the smell of hot brakes,

TrackRat

[tecnic1]

I torched a set of R4-s in 3 days @ VIR in my ITR. I was not impressed with those pads.
I found the ferrodo DS2500s to be much better street and track pads for a little less $.

[nathansvt]

thanks for the opines. I dont think my problem was cooling, although you can seldom have too much cooling. I was running ATE superblue and am pretty happy with it. I've run motul in the past, but it get moisture-soaked too quickly for a street-strip car IMHO. I'm actually pretty familiar with brakes since I used to track my 4800lb Lightning (with wilwood kit). That's a lesson in brake management for sure. In any case, my concern was less with absolute wear than uneven wear. I did expect a bit more out of the porterfields given the life of the stock pads and the relatively light weight of the STi.

Has anyone done ducts on an STi? I crawled under the car this weekend to see if there was an easy way to tap into the foglight holes but it looks like you'd have some really tight turns that would hurt velocity (and you'd have to cut fenderwell?).

Also, I think trackrat may be correct. I was running clockwise. Maybe I'll try the ferrodos next time. The Bobby Archer guy at the track suggested them as well.

[TRM]

Originally Posted by nathansvt

Has anyone done ducts on an STi? I crawled under the car this weekend to see if there was an easy way to tap into the foglight holes but it looks like you'd have some really tight turns that would hurt velocity (and you'd have to cut fenderwell?).

Also, I think trackrat may be correct. I was running clockwise. Maybe I'll try the ferrodos next time. The Bobby Archer guy at the track suggested them as well.

yep, TrackRat is always good for some firsthand related experience. been on track with him too - great guy.

the STi does have a duct for each front rotor, albeit not very funtional. it looks as if they just tried to take advantage of the fact they had to put the plastic splash protectors on the underside. perhaps this could be improved on with some minor modifications?

[nathansvt]

I saw that. I like how it tapers down. Since they dont have much volume and there's not a duct pointing directly to the hub it looks like they decided to make up the difference with a velocity chute. Of course, the 'lip' on the flap probably induces a lot of turbulence which would hinder flow. Also, it looked like the direction of the airlflow would strike the inner wall of the tire going straight and the tread when turning inward. So, you really only get good cooling when the wheel is canted outward. It's a better solution than nothing but there's room for improvement.

The main problem I see is that you can't do much in the way of additional ducting on this intake, because there doesnt seem to be enough clearance to run any flex tubing. You may be able to increase flow a little bit by adding a bulged pan the bottom, but you'd give up some ground clearance.