offroadr35

so Bob after all your experience which pads do you recommend for the PCCB's? Stick with the yellows all the time? My car is used about 80/20 street/track. Also how much should a set of pads cost? How much do the steel rotors cost? I'm just trying to make sense of everything. I have read your other thread about your PCCB maintenance and try to do everything you said, mainly making sure the holes stay open at all times.

I have to believe that with the GT2, some GT3's, some TT's, and now all Turbo S's wearing PCCB's it's only a matter of time before the price for a set of rotors becomes reasonable.

Lastly, it sounds like you've swapped out your pads and rotors about a million times. Do you think you could post a tech article on the quickest way to do it...at least the pads.

Thanks
-Steve

Sloth

Here is another question for Bob or anybody that might know... What do you use to push the pistons back into the calipers when fitting the new pads to PCCB rotors??

offroadr35

i would assume a C-clamp like on most calipers but don't listen to me...

Bob Rouleau

Steve - There are three kinds of pads for PCCB:

Black (Comfort) pads - nice pedal feel, low noise and very good stopping power. Do not use on track however they disintegrate. Porsche issued a bulletin about this.

Green (Race) pads - suggested for track use. Anecdotal evidence is that they fail under load (two reported cases on this board) and you ruin the rotor(s) and potentially your car.

Yellow (Sport) Pads - supplied with GT2/3 from the factory when PCCB equipped. Slightly gritty pedal feel when new, take a long time to break in but the only alternative to the Blacks or Greens. I used the Yellow pads exclusively on PCCB.

The Yellow pad is also standard equipment on the GT3 without PCCB. The front pads are identical PCCB or not. The rears are slightly different because the iron rotor is 330 mm in the rear compared to 350 mm for the PCCB.

With cast iron rotors failure to break them in a lot has resulted in premature failure of the GT3 iron rotors due to excessive cracking. Cracks are caused by high temperatures and a glazed pad overheats the rotor.

Sloth - changing pads on a 911 is a pleasure compared to most cars. While you can buy piston spreaders, my favorite tool for gently pushing the pistons back into the caliper is a worn pad I just removed. Turn the pad vertical and use it to gently lever the pistons back into the caliper. Easy and no extra tools are required. The biggest hassle is getting the heavy duty keeper spring which sits on top of the caliper off and back on. Takes pretty strong hands and the average woman need not apply.

Changing pads - Tools: A metric socket wrench (for the bolt) a pair of long nose pliers (sometimes useful for the pad sensors) and a big screwdriver (if you need to pry up the used pads and or pry up the keeper spring).

Carefully (very) remove the pad wear sensor which is fragile. Remove bolt which runs through the top of caliper. Remove the keeper spring on top of the pads (try not to distort it much - you'll see why). The pads can then be pulled up out of the caliper. Note that there is an anti vibration gizmo (sort of bell shaped) which goes between each piston and the pads. Sometimes one or more will fall out. Do not panic, just push it back into place.

Use the worn pad to gently lever the pistons back into place. Drop in the new pads. If they don't fit, a piston is sticking out too far. Repeat the levering above. Replace the sensors, if your pads are not equipped with the slot for the sensor (many race pads) tie-wrap the sensor to the wire that it comes from such that it is out of harm's way. Replace the bolt through the top of the caliper (6 piston front calipers have this, rears will have a clevis pin - non GT cars will have a clevis pin front and rear) and finally snap the mongo flat keeper spring back into place. Note if the spring is not tight enough, you will get a clunk from the front end which will make you think your sway bar is loose. If you have this, bend the spring to make it push down harder on the pads. I found this out only after the dealer went nuts trying to fix the "clunk" from the front end of my wife's GT3!

If you break a sensor (this happens fairly often) If the wires are still making contact you won't have a red light on the dash. If they do break , you have two choices. Replace the sensor or, short the two wires to the sensor. The sensor is normally shorted and when it touches the rotor friction breaks the connection and your brake warning light comes on. Think of it like a fuse.

After replacing the pads, be sure to pump your brake pedal! Don't be surprised if it goes to the floor the first couple of pushes - that's normal. After a couple of presses the pressure will be re-established and you're done.

Other hints - before installing new pads on a rotor which has been used before, take a few seconds and file a 45 degree bevel on the edges of the pad. Apply a small blob of hi-temp anti seize on the back of the pad - this helps prevent squeal.

Rgds,

bob_dallas

I just use a pair of adjustable pliers (water pump pliers or whatever you want to call them). After you remove the retaining pin and the spring but before taking the old pads out...take your pliers and adjust them so the jaws are fairly wide open but will just fit BETWEEN the two pads (you are using the backside of the plier jaws, then just pry the handles apart. This works for me every time and is quick and easy. Takes a little bit of strength but not too bad - especially if you have fairly long handled pliers.

I agree that the keeper spring or whatever that thing is called is a beeotch to get out - especially on the fronts. Definitely the hardest part.

FixedWing

No. I had much higher pad usage and dust than with the cast iron brakes. I didn't have the hole plugging problem that Bob descibes but I did see other PCCB rotors which suffered from this.

And again, most of the damage done to my rotors, and most of the pad wear, came on the street on long holiday trips. Not on tracks.

I wouldn't even get half of the 5,000 miles out of a set of pads.

Stephen

Mongo

wow, this is probably the best PCCB thread I've seen on this board. Thanks Bob and everyone for shedding light on their experiences once again with more detail



What a great read so far!

Andy

cosmos

So basically the main cause of Iron rotor failure is failure to break in the pad when new?

What percentage of Iron rotor cracking is out there?

Any preventive maintenance for the Iron rotors?

macfly

So basically the main cause of Iron rotor failure is failure to break in the pad when new?


I'm not sure this theory rings true, as I did the first 1,200 miles in my car with the very greatest of ease, keeping things below 4,000rpm, and driving as if the car was made of glass. Having done a super gentle break in (over two weekends) I then started heading to the track, but it took me a full seven tack days at Willow to even get going at a good pace, as I was on the learning curve of it being my first rear engined car, the alingment was way off and I was limited by the mediocre OEM tires.

At 3,600 miles I swapped to Pagid RS19's and MPSCups, that is when the car really came into it's own, and blew my mind as a track star. My driving pretty much consists of going to the track, track days and coming home, and the very ocassional canyon run. My brakes had a very, very gentle break in / bed in period, and Willow as a track is known for being easy on brakes, but now at 6,300 miles they are junk.

BrianPA

Would you reccomend switching to these pads immediately? What do they cost? What should I lot for in terms of signs of premature rotor wear from crappy factory pads? I was pleased with the performance of the factory pads but wasnt aware of the risk of premature rotor failure.

This is for iron discs btw.

Mr. RS

Bob,

I took your advice re bedding the brakes in but they still show severe wear. SInce my last post the car has been back to have the pads changed as they had started to break up.

Opinion has changed and now it looks like the disks will last until the pads need replacing again (maybe 6K miles).

Still not overly pleased, really did think that the technology had been nailed down inthe early cars, guess I was wrong!

P.

cosmos

So it seems that no matter which rotor one goes with (Iron or PCCB) they both seem to turn to dust (no pun intended) within about 6000 miles of use, if one uses the car as intended.

The question now begs, what do you do about it? Do you have to replace the rotors every 6000 miles? Can you buy better rotors? Different pads?

I am sure everyone is thinking what I am, what do you do if you want to drivie the car thru the canyons and take it to the track on the weekends, but not have to replace the rotors every 6 months????

Z06

AP has a 2 piece rotor that will fit on the front of the GT3, soon they will also have a rear set and they will outlast both Porsche PCCB and steel rotors.

cosmos

Got a part number and a price?

I have been running PFC pads on the M3 (Also had Big Brembos) and they were magical. Anyone run 098/01 PFC pads here?

macfly

what do you do if you want to drivie the car thru the canyons and take it to the track on the weekends, but not have to replace the rotors every 6 months????

There are several options on the way.
1.) A full floating kit with aluminum hats & changeable steel discs are on the way from Alcon, should be here late this year or early next. They will work with the GT3 E Brake. (This is fact)
2.) The AP front kit, which is a help, but only a partial solution due to change in brake bias etc.
3.) Brembo are said to have the parts in their parts bin to put a full floating lit together, everything except the rear hat with E Brake, and apparantly they are working on developing that and getting it out now. (nb: this is rumour, not fact.)

$.) Keep buying the discs. I have been told that if you buy the Cup car discs from Porsche 'MotorSports' division they are about $300 a corner, and they'll fit right onto our cars. That is a lot cheaper than the regular $800 a corner from your local dealer.