PSC

This wasn't the first time brakes used hard.

I was careful with the brakes first 100 miles, then increasingly hard on them up to say 400 miles. Since then, another 400 miles pls, they have had plenty of working and the session they 'faded' on was relatively easy on them.

And I can't believe that after 800 miles, they would suddenly go like this because still bedding in.

If so, must be common problem ie every GT3 owner with ceramics on this Board will have experienced it?

PSC

My dealership rang this morning (after stroppy email from me saying why's it taking so long and why am I not being better kept informed) to say didn't know whether brakes had been bled but they had finally managed to replicate fault so I got the impression they now now believed me.

Evidently several technicians tested brakes last week but behaved perfectly. Then on Sat one of them had an Eureka moment (prob a 'Oh ****' moment) as brakes failed.

They are proposing to replace servo and PSM but I'm rather surprised that Porsche GB don't want car shipped back to Reading so they can fully evaluate what's going on, perhaps in conjunction with Factory.

I've never heard of brake failure on a modern car, let alone the latest GT3 RS which should have the most capable, reliable brakes on the market.

I assume this is an extremely rare issue and now that my dealership have verified that fault exists, I thought Porsche would be wetting themselves.

Or perhaps I'm overreacting.

John Boggiano

Well at least you're doing a better job of keeping us informed than Porsche are doing for you...

I suppose this is now yet another thing to worry about when speccing PCCBs.

allegretto

You are NOT over-reacting. This is a potential life-threatening situation. You want a new system, from the pedal to the rotors, and it to be "certified" as working perfectly. Otherwise you need "help". No one likes even talking to attorneys unless they have to, but I think you have to.

If you run someone down or hurt yourself you must have this info "on record". No joke.

chris walrod

Green fade would present a hard pedal, but nothing happening kind of dynamic.

Wow, this could be a scary situation. Glad you got it back to the workshop.

Scott 1996 993c2

WOW ... that'd be some disturbing feeling allright.

Scott

cviles

I know it's not a GT3, but Porsche does use a lot of the same parts across their entire line...

I had a similar problem with the brakes in my 987S. Came in hot to 10a at Road Atlanta, and the pedal squished to the floor. I have no idea how I kept the car on the track.

Afterwards, I spent two hours trying to bleed air out the brakes in the paddock, but nothing got my pedal feel back. It would firm up a little but as soon as I put firm pressure, the pedal would sag to the floor. Eventually, the dealer diagnosed this as a faulty valve in the master cylinder. They drained the whole system, replaced the cylinder and good as new since. My tuner says a lot of 997s that see hard use have had similar failures, so maybe that's something else to check.

LERA GT2

I am having the same issues described in this treat. I have been taking it easy "breakIn" and yesterday afternoon I had the GT3's PCCB oil and filter change. I went for a hard backroad drive this morning and the brake pedal went to the floor!!

Any suggestions?
PSC, did you get it solved?
Is it just air on the lines?

Carrera GT

"Stroppy?"

You're an Aussie? (Or a Brit with a broad vocab?)

It's not all that rare inasmuch as the GT3 is rare, so one or two instances represent a meaningful sample.

I had a similar "spongey pedal" (997 GT3 with PCCBs) and the dealer tech said I was the second case and since then, there's been another one or two I've heard of from all over the planet as I variously learned about the new car.

It seems to be associated with the ABS pump (which bleeds itself under normal operation) and the cure is to use the factory electronic tool ("PIWIS") to cycle the pump and fully bleed the system, flushing it with fresh fluid.

As for "bedding" the ceramic rotor is using the same pad compound as the steel rotor. The bed-in process is the same and the objective is to raise the temperature of the rotor and the pad, burn off the surface and heat the resin in the pad compound enough to transfer pad compound uniformly to the rotor surface.

Some brake manufacturer sites explain this in more detail. In short, most "warped" rotors are actually just suffering from over-heating and an irregular surface caused by careless brake usage (over-heated brakes stopped with the foot holding the pad to the rotor causing patches on the rotor surface.)

LERA GT2

In regards to brake fade, I will try to report the details in case it can be of help to others:

I am driving a 997GT3 with PCCB brakes. I broke In engine, drive train and brakes as follows:

Up to 4500rpm until 500 kms – highway driving – Soft on brakes
Up to 5500rpm until 700 kms – highway driving / back roads – easy on brakes
Up to 6500rpm until 1,000 kms – highway driving / back roads – medium on brakes
Up to 7500 rpm until 1,200 kms – highway driving / back roads – hard on brakes

Oil / Filter change

Up to 8,400rpm – Aggressive on Clutch – High Revs Heel & Toe – Test ABS

After I started driving the car a little harder (from 1,000 kms on), the brakes started to felt spongee. I even noticed that brake action was deeper in the pedal travel (perfect for heel & toe). Then noticed the pedal going down a little farther, but never drove it hard for long period of times.

Today, after the hard drive and having the same strange feeling, I decided to test the ABS and went for 6 –8 hard (ABS test) stops from about 100kms / 60mph. Little by little, the pedal was going down deeper and deeper. Same exact feeling as when you do not cool up the brakes after a hard track session.

After cooling down, brakes are back to “normal”.

Chris R.

PSC, this is obvioulsy a major problem and I just would not feel safe if you continued driving that car. My Cyaman S has great brakes and has never in 10,000KM had the problem you describe. I we switch. I'll just feel better that way.

In all seriousness, there has been some good thinking here: slave cylinder not working correctly ands or the ABS purging itself could potentially caused your problem. I had a similar issue on an Audi a while back after changing to stailess lines; the brakes were very spongee for a while no matter how many times I bled it. It turns out i had to actually brake hard enough to activate the ABS and for it to purge itself (cycle itself). This may not be your case but at least you're not totally alone.
Good luck and if you want a car with safe brakes, lemme know!

BobbyC

I concur with Carrera GT's observations...likely the ABS issue he raised. Agree it's not brake fade...don't think anyone here can drive PCCBs hard enough on the street to cause "fade". Knock-on-wood mine have 2k miles and pedal feel is still solid, actually too solid.

Hope you sort this out. Cheers!