My PCCB again *update*
Discussion
Back in April you might recall my GT2 PCCB woes. Bought from an OPC it was generally accepted by everyone I asked that the brakes were looking worn out. Bristol and Reading both inspected them, however, and unsurprisingly declared them servicable and backed that up in writing so all things considered I went ahead with the purchase.
Since then I've had no problems with them at all in 3k miles. Apart from one time I think they faded on the road but I'd not been going that hard so I don't really know why. I've sure been using them plenty hard with no problems since then.
A few weeks ago the car was used in the evo magazine Scary Cars issue, and I asked their guy to go gently with them at first until he was sure they were ok and after a few laps he was braking really hard and reported absolutely no problems, though he mentioned they were "showing signs of cracking" in the article. Interestingly cracks are normal in manufacture so even new ones may be cracked, though mine aren't cracked at all, they're delaminating.
They look identical today 3k on as they did when I picked up the car.
For peace of mind on the forthcoming trackdays I'm planning, I've had the setup replaced with steel and looked carefully at the ceramics comparing them with Porsche internal use diagrams and photographs used to assessing them.
Sure they're pitted but all the pits are tiny (<1mm) and there are no bare areas (I've seen bare areas on real disks and the documentation and mine have nothing like this). The documentation suggests that any area of 1cm squared indicates failure. The pads were appearing to wear normally too instead of being ripped to shreds as is suggested.
My conclusion is that a certain amount of pitting is quite normal in use. It is where the ceramic friction surface comes off in tiny pockets revealing the substrate and doesn't mean they'll explode into a cloud of dust the first time you use them hard.
The pitting isn't exactly good news though because it does show they've been used hard and/or wrongly but it certainly isn't the end of the world.
But no matter, the steels are bedding in and feel strong so I've got no issues. When I sell the car I'll refit the ceramics.
My honest opinion from experience and from what Porsche have said is that pitting doesn't signify they're knackered and that if anyone is about to buy a car with a certain amount of pitting on the PCCB disks don't worry desperately about it.
SM
Since then I've had no problems with them at all in 3k miles. Apart from one time I think they faded on the road but I'd not been going that hard so I don't really know why. I've sure been using them plenty hard with no problems since then.
A few weeks ago the car was used in the evo magazine Scary Cars issue, and I asked their guy to go gently with them at first until he was sure they were ok and after a few laps he was braking really hard and reported absolutely no problems, though he mentioned they were "showing signs of cracking" in the article. Interestingly cracks are normal in manufacture so even new ones may be cracked, though mine aren't cracked at all, they're delaminating.
They look identical today 3k on as they did when I picked up the car.
For peace of mind on the forthcoming trackdays I'm planning, I've had the setup replaced with steel and looked carefully at the ceramics comparing them with Porsche internal use diagrams and photographs used to assessing them.
Sure they're pitted but all the pits are tiny (<1mm) and there are no bare areas (I've seen bare areas on real disks and the documentation and mine have nothing like this). The documentation suggests that any area of 1cm squared indicates failure. The pads were appearing to wear normally too instead of being ripped to shreds as is suggested.
My conclusion is that a certain amount of pitting is quite normal in use. It is where the ceramic friction surface comes off in tiny pockets revealing the substrate and doesn't mean they'll explode into a cloud of dust the first time you use them hard.
The pitting isn't exactly good news though because it does show they've been used hard and/or wrongly but it certainly isn't the end of the world.
But no matter, the steels are bedding in and feel strong so I've got no issues. When I sell the car I'll refit the ceramics.
My honest opinion from experience and from what Porsche have said is that pitting doesn't signify they're knackered and that if anyone is about to buy a car with a certain amount of pitting on the PCCB disks don't worry desperately about it.
SM
Lagerlout said:
So, can you feel any difference in the handling due to the increase in unsprung weight with the steels?
Well I've only done three hundred miles so far but I think straight away I noticed it seemed to feel different on the road perhaps a bit more stable I don't know. Honestly it might be psychological. Frankly I've asked nothing of it handling wise as yet because I'm dawdling about (<150mph) bedding in the steels.Weight of each disc is (IIRC) 10.8Kg steel, 4.2Kg ceramic.
SM
The ceramic discs on my car looked very much like the original posters description, never had much confidence in them though, changed the pads, bedded them in properly, first time I used them in anger they ripped one side of one disc off. Now has steel Alcons on and what a transformation, the best brakes I have ever had by a mile.
Was it the inside face? I've seen quite a lot of sets of PCCBs and sometimes the inside face seems far more worn than the outside. In my case they're pitted evenly both sides.
Maybe the inside face of yours was outside the 1 square cm threshold and well on its way to failure while the visible outside face was ok?
When you say ripped off one side, what actually failed and how quickly? Did you come steaming up to a roundabout at 150mph, lean on the brakes at the "1" marker and have the disks explode into a puff of dust? or did they fail during the course of a number of stops like that during a track day?
If a track day, did you let them cool off for a couple of laps before coming in from each session?
The EVO driver sure wasn't taking any prisoners with his braking and my disks looked identical afterwards.
SM
Maybe the inside face of yours was outside the 1 square cm threshold and well on its way to failure while the visible outside face was ok?
When you say ripped off one side, what actually failed and how quickly? Did you come steaming up to a roundabout at 150mph, lean on the brakes at the "1" marker and have the disks explode into a puff of dust? or did they fail during the course of a number of stops like that during a track day?
If a track day, did you let them cool off for a couple of laps before coming in from each session?
The EVO driver sure wasn't taking any prisoners with his braking and my disks looked identical afterwards.
SM
Hi; I ran the pads in as per manufacturers instruction, followed this with a 80 mile trip to Donnington. Open pit lane evening so I took a good 2 laps warming the brakes steadily, several hard laps followed by 3 cool down laps. Everything OK. Went out 20 mins later followed the same warm up laps as before, 2nd hard lap coming down the long straight 150+, pressed the stop pedal started to slow then pedal went to floor, pumped the brake again, vibration massive grating noises but luckilly car did continue to slow just enough to get me ass over tit round the s onto the start finish straight, came in the pits. OSF VISIBLE side of disc was fully delaminated and the rough of the disc had taken the pad straight down to the metal. before this the discs appeared used but servicable with NO delamination. The ALCONS I have replaced them with are so much better stoppers and instill 100% confidence. S for the record my ceramic discs looked fine and had seen new pads and track days before, but on this occasion they chose gave up for no reason!! Take care out there....
Edited by PHOENIXUK on Friday 7th September 10:56
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