maximu5

Guys I need some help.

I recently swapped my PCCB discs on my 997 GT3 for Alcons (380 mm front 350 mm rear). I was able to keep the original yellow calipers. I run the Porsche Motorsport thick pads or P50. All in all I have done a day at the Ring (not too tough on brakes) and some 6 hours at Spa since the change.

Today I found that on each front side one of the brake pads had worn totally unevenly (whilst also on each front side one pad has worn nice and even) : some 8-9 mm left at the top and worn to the metal at the bottom. The pistons all still move nicely. I didn’t have such uneven pad wear with my PCCBs. How can the switch to steel discs cause this ?

I also noticed that on the yellow calipers, the imprint of each piston on the pads is of the same diameter, whilst on Cup calipers, the imprint of the (top ?) piston is of a larger diameter. I am told this is to reduce uneven wear. Anybody know if this is relevant and if so I could use Cup calipers on my 380 steels at the front (preferably in yellow, but that is a secondary issue)

I cannot go on going through the thickest pads in just 2 track days, so I am considering fitting Cup calipers because I am told they wear pads more evenly.

Thoughts ?

Tom

rodjac

I had wear problems with the pads and PCCB rotors on my 997 GT2. At least the wear pattern was the same on all four front pads--a lot of wear at the bottom and not much at the top. This was with stock pads. With P50 pads the wear was more even but still with more wear at the bottom. When I switched to Brembo iron rotors and Pagid Rs19 pads the wear was not uneven at all but that was only with one track day. With you having only one pad worn badly I would think that maybe the brakes needed bleeding or there was a problem with a piston.

NoSubEDU

Makes sense...the leading edge will wear faster.

Opposite for rears since the caliper is reversed.

maximu5

Rodjac,
thankls for your suggestions.
However, for it to be a piston problem, pistons on both left and front side would have had to failed at the same time. That is very unlikely.
I also cannot imagine the brake fluid needs bleeding, because the pedal feels as firm as always.
best
Tom

Greygt3

This is normal wear for the PCCB yellow calipers. Take the pads out and flip then to even the wear pattern. Every 997 PCCB owner I know that tracks his car has this problem.

sws1

Doesn't sound like normal wear to me. I understand PCCB causes slightly abnormal wear, but 9mm at one end and nothing at the other sound excessive.

maximu5

I realize I may not have been clear enough : I swapped my PCCB discs for Alcon steel discs, whilst keeping the yellow PCCB calipers. At the same time I also tried for the first time P50 (Pagid green) brake pads. I have never, ever had such uneven wear. This must have something to do with either the swap to steels or the p50 pads or both, because the phenomenally uneven wear happened on both front sides.

I was wondering if anybody had ever bother with 997 GT3 Cup calipers, since they are said to have different sizes of pistons and cause less uneven pad wear ?

997gt3north

- aren't the P50 pads for ceramics, maybe try r19s? and see if you get the same thing?

- you have a unique braking systems (caliper, rotor, pads) combination that probably has not undergone any testing by anyone

- there is no question that the yellow rotors with stock pads on ceramic rotors produce a wedge pattern (sometimes it can be rather significant in size)

- i think i'm correct in that the ECU is suppose to be adjusted to know whether the car is running ceramics or iron rotors (there is obviously something that porsche found - maybe try this)

- there clearly is a reason that porsche used different piston sizes on the cup rotors

maximu5

@997gt3north,

I am trying now what you are suggesting : other pads (rs29) and I will report back.

You are right that the combination is probably pretty unique and my suspicion is that somehow the p50s don't work properly with steel discs (although I think there are others on here who have swapped PCCB discs for steels)

If the rs29 also wear equally unevenly I will try the Cup calipers

best

Tom

sws1

Many have swapped PCCBs for steels, but they made the appropriate pad changes as well.

Stephen Fisher

I have the Performance Friction front rotors and RS14 pads. I had tons of pad at top and almost worn to the metal at the botom (first pad change at the track).

Is this a function of the Performance Friction Rotors? Any suggestions?

Thanks.

SF

MJones

Has something to do with "heat" as well..

Terry L

I have exactly the same wear pattern with the steel brakes, red calipers and RS 29s. All four pads are the same, nothing at the bottom and fat at the top. Flipping the pads could even the wear but you won't have much brake pad contact until the pads wear all the way down to the opposite taper. This doesn't seem optimal. It is not clear to me why this is happening. The leading edge may get a little more wear but it shouldn't look like this unless maybe the calipers are flexing.

crispenigl

Sounds like a defect to me :P

sasportas

I have the exact same front pad wear which I'm told is completely normal considering the mounting position of the caliper and the camber of the front wheels. Also, if you run a 2-piece front rotor, the tappered wear is accentuated.

Does anyone have a "rule" or limit as to how far you let the pads get worn at the inferior (or leading edge) before you replace?

I'm just curious.

Thanks