PCCB question...

Is it true that the PCCB brakes are warrantied for life? This is the info I got from my sales guy I keep seeing all this talk about them only lasting 1500 miles and I'm begining to have my doubts. Are the rotors and pads warrantied or just the rotors or neither? If anything is warrantied how long does the warranty last and what are the terms? Do the replacement rotors really cost $8000? What about pads?

I have heard the same and would be curious to know more. FWIW... from my research the 1500 mile thing came from hard track use by a group of testers set to destroy the brakes. I have also heard about some issues with the first generation of PCCB. However, it is to soon to tell about the second gen PCCB brakes fitted to the GT3. I would hope that PCNA would stand behind this expensive option if they were to wear prematurely.

Read the last two paragraphs on this Porsche web site page: Pccb brakes I think rotors and pads should be considered consumables, like tires. To expect Porsche to replace these parts at no charge is expecting too much in my opinion.

Is the cost for rotors in fact $8,000 though? If so I think it's porsche that's expecting too much. I was just going by what my salesman told me.

The PCCB option by itself is over $8000 on the GT3. I would hope that rotors by themselves are a lot less than that. However, I have heard that a set of rotors is about $8000. I am hoping that the price comes down as technology improves and as Porsche tools up to meet demand. I hope I have to wait the advertised 100,000 miles to find out.

The factory option is $8K but if you seen the prices for the PCCB upgrade kits for the TT, the list is around $18K and the lowest I've seen them advertised for is over $12K. The rotors are clearly the most expensive part, since the calipers and pads are the same as the steel rotor cars. Individual parts are always more than a kit price, so I think the $8K price I've seen listed on other boards is pretty accurate. Porsche says the rotors will last 100K miles but there is no special warranty coverage on the brakes. Also if you read you warranty book closely (page 8, I think) anything that happens due to track use is excluded from warranty. So don't expect PCNA to cover the cost of these rotors if you wear them out on the track. Karl

So are the rotors covered for 4 years 50,000 miles? Like i'm really going to tell them I was on the track!

The stock brakes on the Porsche are already exceptional. They can almost lock up the tires even at high speeds. I suppose you could even lock them up if you really stood on them. Or at least on the C4S. I have not heard of fading being an issue. A complete replacement, rotors and pads and labor, is $1700.00. Those are Porsche prices with no haggling nor research. I can understand why you would want PCCB on a race car. Heck, rumour was you could run the 24 hours of LeMans on one set. I don't mean to be a wet blanket, but why would you want such an expensive thing on a street car if the stock brakes are so good?

OK... I am starting to get buyers remorse here. Just got off the horn with an area parts dept... I figure I could purchase 4 944's by the time I replace all four rotors. Heres hoping they last as long as claimed... No offence towards the 944, they are great cars.

Ok so what was the result? How much are they?

If I understood correctly, it worked out to be just over $12k per set... ouch!

Oh my god. Horse****! I might have to change my order! This may sound stupid but is it possible to just throw on steels after the first pair of PCCB rotors wear out if you can't claim it as warranty?

From page 8 in the warranty book: "This Warranty Does Not Cover: ... The replacement of expendable maintenance items (such as ... work brakes) when the replacement is not due to a defect in material or workmanship." No way they are going to cover the rotors if you use them up after 5000 miles. You won't have to tell them you tracked the car, they'll figure it out fast enough. You can switch back to the steel rotors, since the calipers are the same but why waste the money? Karl

I thought there was something different other than the rotors something about floating hats or something on the calipers?

If this application is for the new GT3 you can use the same front calipers as the PCCB and use the same P90 pads. All you would need for the fronts are a set of 330mm GT3 steel rotors. For the rears you will need the GT3 calipers that have the correct offset for the 320mm steel rotors, you can use the P90s pads for the rear. GT3 PCCB rear rotors are the same diameter as the fronts 330mm. GT3 rears in the steel rotors are 320mm, the calipers are the same construction just the offset is different for the 10mm diff in rotor diameter. Hope this helps.

Hmmm... What if I were to just use 330mm GT3 steel front rotors in the rear? If that won't fly any idea how expensive it would be to modify my PCCB setup to use steels in the rear? I want to order the PCCB for resale value reasons on the car and see how long they last but if they do wear out I think I'd need a home equity loan to get some rotors for my car. $8k for brakes is insane. I might expect to pay that on a McLaren F1 but $8k for brakes on a $100k car is insane.

I guess you could if they offer a gt3 330mm steel for the rear. The new GT3 has 320mm steel rears. 320mm would be much lighter. Ther rear calipers are around $600 apiece. The PCCB P90 pads work great with the steel set up. Abit soft but easy on the rotors. All the GT3 with steel rotors are being delivered with the same P90 pads as on the PCCB's. Most of the core GT3 owners are getting the steel set up, all the Porsche Cup Cars have the steel for track set ups. I think theres still needs to be more improvements with the PCCB's. Heres what they look like when they get cooked.

What I was saying is... IF the car is originally equiped with PCCB which 330mm all around, and the steel front rotors are 330mm why not use front steel rotors all around as replacements for the PCCB? Would that be feasible?

I also chose the PCCB for the resale. I am thinking one of two things is going to happen... either the price for the PCCB rotors will come down in the long run or there will be a way to switch to steel rotors. I saw the photo that Oak posted (along with several others) while lurking around at Rennteam. I think they were sent to somebody there, but with little exclamation as to what happened. But looking at the pad, one could speculate that someone took them beyond there useful life.

The steel rear rotors on the GT3 are 330 mm. The fronts are 350 mm as in the PCCB. There are no 320 mm rotors in Porsche's lineup at this time.

Viken, My bad, you are correct. I have these 350mm and 330mm on my turbo! I got the stock front turbo rotors sizes mixed up. Front 13.79"/1.34" thick = 350mm Rear 13.00"/1.10" thick = 330mm brh986, I don't think that would be feasible, due to the different thickness of the rotors. It would be a nice if Brembo would make a direct replacement two piece floating rotor. You maybe able to find an aftermarket two piece floating rotor. I have been looking but haven't been able to found a replacement.

Oh boy that's unfortunate. Hopefully these issues will work themselves out so I don't have to sell my daily driver to replace my brakes!!!!!!!!!

brh986, you should be fine for street and occaisional track use. I wouldn't worry about it. Most of the guys that have the PCCB's are very happy with the performance. Although a few have mentioned some wierd braking sounds.

OT but love that body kit and wheels Oak, what are they?

Thanks, they are just the factory Aerokit and the HRE 843's, brushed centers and polished lips.

I was about to change my '04 TT Cab order to remove the PCCB option when I read the short rotor-life postings. Some users with REALLY short life experiences (like 1500 miles) on the track contrasted to 100,000 or 150,000 mile expectations from Porsche factory sources really got my head spinning. How could they both be correct? Here's my theory: The really quick-to-burn-up guys were fooled by the lack of fade. Most racers are sensitive to fade, and adjust their driving so that they can work around it by not going in as deep, etc. However, they consider fade as an enemy holding them back, not a friendly warning of impending mechanical doom. With iron rotor brakes of the standard sort, the fade shows up before one can really hurt the rotors. Change the fluid and pads, and, bingo, one is back in good shape to try again. Apparently, ceramic brake rotors don't fade nearly as early or as much under really heavy conditions, and it may be possible to badly hurt them, without the traditional danger signs appearing first. If the car keeps stopping, one keeps going in deeper and deeper, until ...? Catastrophic thermal overload. The rotor becomes the fuse! I propose that track use of PCCB may be an intellectual exercise that is very unusual for the average racer and may require painful acclimatization. With 95% street driving and a few DE events, I am no longer much worried about PCCB rotor life in my situation. I kept the TT Cab order as is, with the PCCB option on the list.

"I don't mean to be a wet blanket, but why would you want such an expensive thing on a street car if the stock brakes are so good?" because the PCCBs are 1/2 the weight and it's all unsprung savings.

Now thats a theory I can live with...

Exactly. 40 lbs in unsprung savings is equivalent to what in sprung weight? 5 or 10 times that?

I have just about the longest experience that anyone has had with PCCB's. So far, about 48,000 km on them. For the problems I've experienced search here and on Rennteam.com for "PCCB". My front rotors have been replaced once under warranty (ABS damage to the inside surfaces). Also, the wear rate was quite high. The bigger problem is that they still do not have pads which will survive the heat. The worst damage I've done to the pads has been in hilly conditions without really trying. If you use the car hard, expect to replace the pads very frequently. Once they have been overtemp they are garbage. I've demanded that they remove the PCCB's and retrofit the car to its original cast iron brakes. PAG has so far refused. I'm 100% sure that sooner or later this will end up in litigation. Oh, it is a misconception that the GT3 has been delivered with "second generation" carbon ceramic rotors. Development was not completed in time for this. I don't even know if current GT3's are getting them. PAG talked about them but didn't actually deliver them. But in any case, the additional cooling of the second generation will do nothing to solve the ABS problem. I have had both systems on my car so I can confirm that on bumpy roads the lower unsprung weight is noticeable. Stephen

Wow. All I can say is THAT SUCKS! Is this the typical expirience? Is there anyone here that has PCCB that doesn't have terrible noise and premature wear problems? And FixedW a question on the ABS thing, you say "There has been no solution to this problem and the promised (but I believe not yet delivered) second generation rotors do not cure this problem. " - how do you it's not cured by second gen rotors? My car isn't getting built until around april '04, maybe they'll fix it by then?

PCCB rotor failure is caused by two different methods. The first is by getting the rotors over their design temperature. When this happens the rotors literally start coming apart. The fibres in the rotors start sticking up and being ripped out. This can happen very quickly and be quite destructive. The second is due to the high frequency of the ABS system on the 996. The rotors are pounded by the ABS until bits start chipping off them. By the time they were replaced, the inside surfaces of my rotors looked like extremely rough sandpaper. Not smooth at all. Needless to say, the pads don�t last very long once this starts to happen. The second generation rotors are claimed to provide better cooling through 30% additional airflow (they changed the vanes inside the rotors I believe). This probably is sufficient to solve the rotor overheating problem. But it does nothing to solve the ABS problem. I don�t know of even any attempts at this time to fix the ABS problem. Noise is only really an issue once the pads have been destroyed through overtemp. An employee of the importer described the sound as being similar to metal-on-metal after someone forgets to change the pads. Drive through town and everyone will look at you. People who start to J-walk immediately get back on the curb the second you touch the brakes. I could live with even this if it wasn�t for the terrible pulling of the car as the pads heat up unevenly. The crispness of the new pads is completely gone. When you pull them out they look like brownies that have been in the oven for about two months. Whether you have good or bad experiences with this system boils down to how you use the car. If you never drive it hard then they will actually last many times longer than will the cast iron system. Stephen This is ABS damage. The rotor looked a lot worse than this by the time it was replaced. Not smooth at all. This shows a rotor where the surface has gotten too hot, the fibres have stuck up and been ripped off hence the pattern. This isn't exactly general temperature failure of the rotor but it is on its way there. Add a little more heat and the rotor would have really started to come apart. But compared to the ABS damaged rotor surface, this surface is still relatively smooth. Note the dark patches on the rotor. That's pad transfer from the overheated pads. These were the first set of P40 pads. You can see from the crazing why the pads on the other Rennteam pictured Porsche broke up. In fact, later sets of P90 pads looked considerably worse than this. This set was replaced very quickly with P90 pads. The importer actually told me that he was afraid to let me use the most recent set of P90 pads while he waited for replacement pads to come in. They looked that bad. And I had only taken the pads on a holiday trip to Sicily and back. One trip through the Alps was enough (on just a little French single-lane "D" road!). Some pads have worn out unevenly (similar to the other Rennteam photos). That's risky because it is possible to wear out the pads without the sensor tripping. Metal on the rotor will destroy the rotor. For large versions of the above look here: http://www.986host.com/gallery/Fixed...otor_14?full=1 http://www.986host.com/gallery/Fixed...otor_05?full=1 http://www.986host.com/gallery/Fixed...rbowong?full=1

WOW. Holy smokes!!

For those of us that already have the PCCB rotors... anybody know the correct way to break in and bed the pads and rotors? I know I have read it before somewhere, but I can not find it now. TIA

I'm the guy that first posted the 1500 track mile life for PCCBs. That number came from Porsche Motorsports when I ran into a group doing pre-LeMans testing at Sebring. They also specify a different compount brake pad for track use which can be ordered thru them. For details ask your dealer's service department about the tech bulletin on track use of the GT2 (I don't think there's a corresponding GT3 bulletin yet). For PCCB break in info I think we need to hear from watt - he seems to have much better luck with the brakes on his GT2 than FixedWing does. BTW, when changing wheels on a car with PCCB rotors it's a good idea to use two of the wheel guide bolts that you can thread into the hub. Hitting the rotor with a wheel while mounting it is _not_ a good thing.

FYI this info is from PCNA about the racing pads: Brake Pad For Racing Use (only for racing or racing circuits): Installation: These pads can only be retrofitted (at the racing circuit). Not for street use. Properties: Reduced wear on the pad at high operating temperatures. Identification: All pad side areas are light green. (Sold each, not as set) 996 351 940 92 Front Axle Brake Pad/1 ea. 996 352 930 90 Rear Axle Brake Pad/1 ea. These pads (for racing use) are only available from Porsche Motorsports North America (PMNA).

Hahahaha The only problem with that is that Watt is using the technique that I suggested to him. Excerpted from my email to Watt: I've had good luck with this technique ... as you can see! Very true!!! (Photo taken in Turkey following a blowout.) Stephen

Fixedwing is correct. There have been many discussions on the ABS controller in PCCB applications, and to my knowledge no firm decision has been taken. The issue, as I understand it, is that there are clearly two different programming requirements (CB vs Steel), and there is a great reluctance to fit different systems, since the changeover costs would be quite high (New controller, solenoids, ABS Pump - among other changes), and the possibility of the owner/operator changing rotors at some time without making those changes. Until such issues are resolved, PCCB use is, IMO, for those "early adaptors" out there (like my dad and his 70's "beta" tapes....) J

Where do you get those pins? How do you get them out once the wheel is on so you can put the lugs nuts on?

brh986: The GT3 uses wheel bolts, not studs (as with all current production 986/996 models). The toolkit should come with one wheel guide bolt and your dealer's parts department can order a 2nd one for you.

Hi JeffES, I'm hoping you can expand on your statment above.. I can easily understand why you would want different ABS calibrations for the PCCB brakes vs. Cast-Iron rotors (steel rotors aren't used on cars anymore... (read more here) ). With a completely different relationship of pressure to braking torque, and I'm sure a completely different temperature dependency as well, the ABS is going to have a hard time doing proper control on a PCCB car, when it was originally calibrated with the cast-iron rotors. This seems evident by FixedWing's experience that the ABS system caused the wheels to carry a lot more slip when he had the PCCB's on his car, compared to when he had his original iron rotors. Since ABS is only a partially closed-loop control system (it directly controlls brake fluid volume, yet it's feedback signal is wheel speeds), it heavily depends on calibrations that help it predict how much fluid it needs to remove when a wheel goes to lock, or how much it needs add back to a wheel to get it back to the optimum slip level. If the PCCB brakes have a higher friction level than the Iron Brakes, then most likely what you are seeing is that the ABS is removing too much pressure initially when the wheels go into slip, then a few ms. later it is adding too much pressure, which cause the wheels to go into more slip than optimum. The result is a lot more pressure change than needed - what is often nicknamed "bang bang" control, which is better than nothing, but is not optimum for vehicle stability or parts durability. Anyway, what I don't understand from your statement, is why you would need so many changes just to change the calibrations on the ABS. Really, the only change should be needed in the electronic software. At worst case that means a new electronic control unit, at best case most new ABS/TC/DSC (PSM) systems can be reprogrammed over the vehicle communications bus. I don't see why the hydraulic unit, or solenoids, or pump would really need to be changed at all. (FWIW, these are all part of one unit part these days anyway). Can you fill us in more about what would require such a drastic hardware change? Cheers, Keith '95 968CS

Extremely interesting post Keith! I have noticed a significant difference in the feel of the ABS system on the PCCB brakes vs. the cast iron brakes. With the PCCB's there is much more tyre squeal. The car is noticeably less stable. If I do not get off the ABS it is impossible to make the car turn-in. It feels as if the ABS is being more aggressive. What I didn�t realise until now was that this might actually have been exasperating the ABS damage to the rotors! The �bang bang� control that you describe would be exactly the wrong thing. In fact, I wonder if they were to re-calibrate the ABS system would this entire problem just go away? Is this an example of PAG pinching a few pennies in development at the expense of their loyal customers and in the process, earning a potentially great new technology a lousy name? Stephen

Someone said that they fixed the over heating damage problem but the ABS problem still remains (not sure if that's true about the overheating)... Is it possible that if they fixed this ABS problem the rotors would last much longer than 1500 miles on the track?

stephen, the progressive, repeated braking method you suggested to me has worked great on all 3 pccb cars i have owned. i just bedded the gt3 that way. the only issue i have is cold lack of braking in the gt2, but not in the gt3. the 3 must have a "comfort" pad. i have been hitting the brakes hard in the gt2 doing 700 mi high speed runs to Nevada and they work nicely and actually get better as they get warmer. as i said elsewhere, my senior PCNA executive swears to me they have had 1 claim in USA, a car mag "trying to ruin them on the track". i think yours were faulty or my 3 sets were particularly good, and the statistics are with 3:1.... altho' not conclusive. and maybe euro pccb is different than usa???

The standard pad for the PCCB equipped vehicle is F:996.351.948.01 R:996.352.948.90 the pads have a yellow finish on the lateral surface. The pads are for "Sport Driving Street Use" according to Porsche. Also according to Porsche: "Suitable for circuit use. However, this entails very high operating temperatures and results in higher pad wear compared to the pad for circuit use" The comfort pad is black. F:996.351.947.01 R:996.352.947.01 This pad is according to Porsche: "Only suitable for normal street use"

HerrTraction, Koblenz in your sig - what a neat city. As to your points, First - the "warped rotors" article you reference is very questionable. I'll let it go with the comment that if you walk into any kitchen and inform the chef/cook that cast iron doesn't't warp, they'll either laugh at you or hit you on the head with one of their castoff cookware pieces.... Second - your description of the ABS process w/ PCCB seems to be spot on. If the pulse cycle is optimized for a given friction range (iron), then if (and I repeat IF) the friction range for PCCB is outside of that pulse cycle, then..... ouch! Third - you're right. Today's systems typically integrate all components of the ABS system (unlike some early systems). As to the change of system components, my thought is that if (there's that word again) the differences in pulse cycle and fluid pressure changes are that great (between PCCB & Iron), then perhaps the unit components may require some changes. If you examine the data on the specific sub assemblies you will find that there are specific performance ranges on each component. If indeed PCCB units can be damaged by the ABS system as currently calibrated, then the PCCB's optimum operational parameters may be outside what is available with only a software change. FixedWing - I tend to support your statement: "Is this an example of PAG pinching a few pennies in development at the expense of their loyal customers and in the process, earning a potentially great new technology a lousy name?" Thus my "early adapter" comment earlier in this thread. I also believe (does anyone have any real data on this) that the different pads are a bit of a "stop gap" solution.... Sorry for the lengthy post, and I hope this makes sense. J

Of course, I can't spell "don't".... (sigh)... J

Jeff, Thanks for your reply. Koblenz is nice, a bit sleepy, but notable by being only 50km from the ring (going there momentarily) Rotors: I'll buy you a beer if you can tell me who makes Porsche's rotors (besides Textar), and a reference indicating they're made of steel. I'm not a rotor expert, but I understand steel rotors warp even more readily than cast iron... Hydraulic Hardware changes: From going from cast iron to PCCB it seems that less pressure variation, and therefore less fluid flow changes are needed. Because of this, the isolation, dump, and supply valves of the current ABS/PSM unit should work fine. All the accumulators should then be big enough, and the pump will be sufficient capacity. It's possible that a differently configured Hydraulic unit * could * use slightly smaller orifices in the valves, slightly smaller accumulators, slightly smaller pumps and possibly a smaller pump motor... but it's by no means necessary for this instance, IMHO. Most VM's use the same hydraulic unit across a whole model range of vehicles (for instance, all Passats or all F150's), even though there are slightly different weights and brake sizes between some different models. These differences are accounted for in calibration differences. Most modern systems can accomodate 2 or more calibration sets in the same ECU, which are then even be selected when the vehicle starts acorrding to a telltale from either the communications bus, or from a hardware signal (two pins jumped or something) .... this could also be possible for our scenario - a sensor or a jumper that tells the ABS which calibration set to use for the brakes that are installed. OK, N�rburgring beckons (open all day today), so I'm off. Cheers, Keith

Something else that flashed through my brain earlier this morning....� If the ABS calibrations are affected by this, then the PSM calibrations will also be affected. For yaw control, the PSM controller calculates exactly what size (counter) moment it needs to affect on the vehicle, then calculates what pressure that would be (based on brake size and friction). Then it applies the brakes by opening the valves for just the right amount of time that it thinks (again through calibrations) that it needs to get the desired pressure. This is even more critical than for ABS, because you typically want to get "the exact right pressure, right away" when the vehicle is about to spin. Too much, and the intervention is intrusive, not enough and perhaps the car gets a little looser. In our instance, since the PCCB brakes have higher friction, then the PSM system will probably feel more intrusive than with the cast-iron brakes on, since it will be getting a bigger torque value from the wheel than it thinks.. FixedWing, have you felt this at all? I'm assuming that you don't engage PSM nearly as much as you engage ABS Cheers, Keith

Traction, No, my understanding is that virtually all rotors today are cast. If I implied that steel rotors are used, I apologize. As far as the same units used across model ranges, you're right - and it's a major issue today. The use of common systems across a range of weights and sizes has raised flags in steering systems, braking systems, and even HVAC systems. The question still is unanswered then - does the current ABS unit have the capability to optimally control both the "Metal" and the "PCCB" hardware? If so, would changes be required in only the calibration (software), or in both the calibration and components. I'd be surprised to learn that the current ABS hardware, with no changes whatsoever, could handle both PCCB and cast iron systems on the same car. Any insights??? J Would there be an impact on PSM? Sure! An incorrectly calibrated unit anywhere in the system(sensor or output) would have a negative impact on overall performance.

This is most likely a real stupid question but since I am on the list for a GT3 for next springs delivery and I did plan to order the PCCB brakes for their lightweight (not resale value). I was wondering if the ABS can be turned off? Most cars I have seen with some form or traction control allow that to be turned off but I don't think I have ever seen this apply to the ABS?

No. The ABS system cannot be disabled at the user level. PSM (Porsche Stability Management) can be disabled (push button), but PSM is currently not available on the GT3. J

I didn't think you could shut off the ABS. I just got the latest Autoweek last night and there is a small blurb on the 04 GT2, it mentions that PCCB is standard and that there is a new ABS program to go along with it ( as well as more power and 7lbs less weight). Hopefully this will address the ABS part of the concerns with the PCCB brakes and will also be included on other 911 versions using the PCCB Brakes?

RE PSM - I guess this is not as much of a point to worry about, as most PCCB cars are GT2's and GT3's which don't have PSM available. The only way to find out if a hardware change is absolutely necessary or not, is to find out from Porsche or Bosch. My educated guess (from professional experience, but not including work with Porsche or Bosch systems) is that the difference could be sufficiently managed with calibrations. Could you perhaps get yet an additional small improvement from changing the hardware too? Perhaps. My educated guess is that you can get at least 90% of the way to "optimum" with calibration changes. So here's an interesting question for the GT3 and GT2 owners - how many of you would consider PSM if it was an option for your cars? Would you pay $2k ? $5k ? The number of GT2's that have been completely written off due to accidents is quite high in Europe. Some friends and I have theorized that this could have been prevented or reduced with PSM availability... Yet other friends argue that PSM would take away from the "pure Sports Car" image of the GT2 / GT3. Cheers, Keith

i would not pay a dime. gt2 is correct the way it is. for psm you can buy TT and get 4wd as well

I'm with watt, not even remotely interested in PSM!

I would take it if it could be entirely disabled! Unfortunately from what I'm told even when it's turned off it tends to reactivate itself. IF you could entirely turn PSM off it would be incredibly stupid and arogant to refuse it. Granted you don't want it on the track but for casual driving around on the street it's a very good thing.

HerrTraction: If PSM on a GT3 offered the capability to disable it completely for track use I'd be interested. I know my brain isn't as engaged in driving when I'm on the street vs. the track and for those times I like the extra insurance. And being as it tends to rain a lot here in FL, let me tell you that driving at Sebring in pouring rain with a PSM equipped car gives you a new appreciation for the capabilities of the system. 64lusso: The Bosch 5.7 ABS system in the new GT2 is just updated to the same version as the new GT3. Quoting from the GT3 Product Information book: "This updated system provides a more rapid response and greater sensitivity than the three-channel technology (5.3) used in the original GT3. Another advantage of version 5.7 is its four-channel layout, i.e. all four wheels are mananged on an individual basis."

Can't help but wonder then if the ABS system's operating parameters are why PSM is not available on the two wheel drive cars that can be equipped with PCCB? Thoughts?? J

As far as different units vs. calibration only, I refer to my experience with the GM C/K vs GMT 800. GM engineers/managers approved the use of similar ABS hardware across several varients of the full sized pickups, relying on calibration only to handle the differences. The real world experience was quite different though, forcing a re - examination of that line of thought. Today, there are several different ABS hardware components found across the GMT 800 line. My question/observation still stands - can every part of the existing ABS hardware work optimally with the very different friction coefficients of cast vs PCCB brakes? I'd like to see data to back that up.... J

JeffES: Part of the marketing on the GT2 and GT3 is they're cars for the driver that doesn't want to be coddled by electronic aids. And the lack of PCCB for the standard 2wd 996 line may be more to do with parts avaialbility or product positioning as I _think_ I've seen comments in print that Porsche eventually expects to offer it on all models (probably not the Cayenne though ).

Steve, Good point on product positioning. I too have heard the "rumor" about PCCB on other products, but I would speculate that having a compatible ABS system is an issue.... Also - enjoy that GT3! I've driven the previous version, but can only imagine how great this new one is! J

I agree that the ABS is not set correctly for PCCB. I have been on the brakes hard at speeds of up to 190mph and have had the front wheels lock and the ABS cycle at these speeds. This has never happened in any other ABS equipped cars I've had (including a 993 RS). I believe that the sensitivity for the ABS is not calibrated correctly for PCCB. Oh and I would love to have PSM, so I could turn it on when driving on wet, winding, leaf strewn english roads with the wife on board. Just would have to be able to completely turn it off when wanted. Guy

AFAIK there is one HCU for all light duties, and one HCU for all heavy duties, (both 3 channel) and then a 3rd HCU for the vehicles with stability control (4 channel). What information do you have otherwise? Which part proved not to be robust to the varation? Isolation valves ? Dump Valves? Pumps? Motor? I don't think the difference in going between 996 Iron brakes and 996 PCCB is nearly as much as going from a vacuum boosted GMT800 1500 4.8 to a hydroboosted GMT800 3500 Duramax dually ?? Back in the late 80's, and early 90's, Audi used the exact same ABS unit, hydraulics and calibrations, on all their models!! I stated before, I don't know. I don't have direct experience with Porsche's Bosch units, sorry. I can only offer my educated guess. Perhaps you can explain more why you think otherwise ? Which parts need to be changed and why? Regarding no PSM on the GT3 or GT2, perhaps it has something to do with the LSD that is in those cars as well? After discussing this in another forum before, there was a general consensus that the cost of setting up PSM for the GT2 / GT3 (integration with the LSD, as well as a full re-calibration effort) was too high for the commercial benefit... And not like Porche (nor Bosch) have a abundance of engineers sitting around, so it may have also been a workload issue as well. Cheers, Keith

HerrTraction: The 40th anniversary 911 comes with a true LSD and PSM so they can be made to work together. The LSD in the anniversary car is set for 22/27 rather than the 40/60 of the GT3 (and I think the GT2) though so there may be a limit on how much lockup you can have in an LSD and still use PSM. And before brh986 comes along and asks what 40/60 means, Porsche uses an asymmetrical LSD with different lockup under acceleration and decceleration. In the GT3 it's 40% and 60% respectively.

You're right - a weak LSD will not pose a large interference to ABS or PSM Yaw-Correction inteverventions. However a strong LSD will cause more problems especially when trying to hit individual rear wheels for understeer control. Cheerss, Keith

Oh this thread is getting very interesting indeed!!! First, I'm amazed that you say the GT2 is not correctly configured for PCCB's. This car is standard with PCCB's! Is it possible that the PCCB brakes were not ready at the time of testing and therefore all of the development was done on cast iron rotors??? We know that they had trouble delivering the ceramic rotors at the beginning of production and that they weren�t ready even for testing much prior to that. On my Turbo, I have not had the experience of my brakes completely locking up. They do, however, get very close to this point. In the dry the tyres squeal and there is very little directional control left. So far, no problem in the wet but I have to wonder how ideal this is for safety? Now more interestingly, I have found that the PSM sometimes over controls the car. Previously I had put this down to my reacting at the same instant as the PCM and the corrections being duplicitous. But now, in light of the information in this thread, one has to give serious consideration to this being the real reason. On the coefficient of friction of the ceramics vs. the cast iron brakes, this varies a lot on the PCCB's depending on the condition of the brake pads. If they are new then the pressure is lighter. If the pads are shot, then the brake pressure required is considerably greater. This also has to interfere with the ABS/PSM system. Also, this must affect the front/rear balance as the rear pads do not become overheated to the degree that the front do. PSM obviously isn�t an issue on the current GT2 and GT3. But it is on the Turbo, C4 and C2 � all of which now come with PCCB brakes as an option. I think I�m a reasonably capable driver. But I wonder what will happen to the average Joe driving a C4 in the rain when something nasty happens? Stephen

HT - Yes, and many (myself included) believed that to be an issue w/the big Audis braking capability. As far as the trucks, remember that the length (routing) and diameters of the brake lines themselves are a hardware issue, and had to be resolved (longer runs meant lower pressures, etc)... J PS - FixedWing - there is no question that PCCB's were "rushed to market" - there was a real attempt on the part of some at PAG to beat DaimlerChrysler to market w/ the composite ceramics....

This is very interesting indeed, could it possible that Porsche had done initial testing with out regards to the weight difference between PCCB and cast counter parts? The unsprung weight difference and rotating mass has to come into factor. If I recall, the first GT2's had arrived with cast rotors due to the PCCB's being not available at the time of production, but these owners were promised retro fit when the PCCB's were available. I wonder if some of these owners know if the ABS software and hardware had been addressed when the exchange had been made. Or if Porsche had just exchanges the rotors only. It seems that under aggressive driving the ABS and possible braking pressures are much too aggressive for the PCCB rotors. Under normal and moderate driving condition these "off calibrations" would not be so evident and could be the problem. This could be the reason why the first sets seem to have the most problems, hence Porsche has upgraded the new ABS software and hardware. I know it's too early to tell with the new PCCB on GT3's I think time will tell.

Jeff, I see only one performance change in the ABS hydraulic components for GMT 800 from it's introduction. The 20 series trucks were moved from the 10-series HCU to the heavy duty 30-series HCU (only difference is larger accumulators) in mid-year 2002. There have been a few other changes to the HCU's from time to time for cost or packaging optimisation, but no performance-affeting changes that I can see except for what I mention above. If two HCU's can cover the entire breadth of the GMT800 range from C10 to K30 (and a third for optional 4-channel stability control), then I think with the same weight (roughly), same wheels as before, same tires, same wheelbase, I don't see such radical changes *needed* for the ABS Hardware! Besides look at it this way. They released these vehicles into production with the same ABS unit all together in the first place. Therefore either they meet all the safety regulations, or Porsche is cheating. Making a calibration-only change to be less agressive in braking for PCCB applications could only improve the performance from what is already "production". Cheers, Keith

HT, your're making my point for me. I'm the one saying that broadbased applications do NOT work out well at the extremes, and I do believe that the change from iron to PCCB DOES fall under the heading of extremes! I just don't know how a simple change in software can change the time AND VOLUME of pressure (last time I checked, the pressure of any fluid in any system is set by it's mechanical attributes). Until I see some data to change my opinion (yes, I fully admit it to be an opinion), I would say that the change in components does constitute a major change - requiring new parameters in pad application time, pad force, and point of activation. Otherwise, why the problems???? Respectfully, J

Oak, If I understand our esteemed experts correctly, it isn't so much that the ABS pressure is too great but that it is not correct resulting in continuous corrections and unnecessarily high pulse rates. Has Porsche upgraded the ABS software and hardware? From the explanation I saw earlier this seemed like a change but not necessarily one intended to address this issue. More a matter of bringing the system into conformity across more of the product line. And most critically, I don't believe there are any new Porsche PCCB rotors yet. Porsche AG has talked about it, put out press releases, etc. but my understanding is that it wasn't yet ready for the release of the GT3. I don't even believe current GT3's are coming with the supposedly improved ceramic rotors. Someone know differently? Stephen

Jeff, Perhaps I should have pointed out that the only difference between the "light" and "heavy" HCU's for the entire GMT800 range is the low pressure accumulators, which are in now way related to the speed, or timing of the fluid cylcing.. The pumps, motors, and the orifices of the hydraulic valves that can effect the applying and releasing of pressure/volume are all the same. And since the PCCB should require (from what we can see) *less* volume, then in effect the accumulators would be "oversized", the only harm there is when you have a brake failure on one circuit, which is primary a "regulations" requirement. And it apparently meets "regulations" now..... Jeff, If you have a brake system without ABS at all, then for certain, the mechanical attributes of the braking system are the only thing controlling the pressure (that and the driver ) The driver can chose to add, hold, or release pressure from brakes with his foot. How much goes to each brake in proportion to the other, is decided by the mechanical components of the braking system. With ABS, what you are adding is the ability to do the following: A) Reduce the pressure from what the driver is requesting with his foot B) Hold the pressure at a desired point at or below what the driver is requesting with his foot C) Reapply the pressure up to what the driver is requesting with his foot. And the bonus is that you can do this separately for each individual wheel (the rear wheels usually being controlled either exactly the same (3-channel) or very close to the same (even in 4-channel the rears are not completely independently controlled for stability reasons) So then, what controls when the pressure is released, how much is released, how long the lower level is held, when the pressure is re-applied, and how much pressure to reapply? SOFTWARE. The mechancial components of the HCU (hydraulic control unit if I haven't explained my abbreviation by now) do impose limitations on that, such as the maximum rate which you can reduce pressure, and the maximum rate that you can apply pressure, and the minimum size of incremental steps that you can have. For example, lets go through a simple ABS cycle on one wheel with two different cars, each being correctly calibrated for their brake calipers, rotors, and rotating inertia.. We'll call it them Iron and PCCB. 1: Driver applies brakes gradually 2: The brake torque starts to exceed the traction ability of the tire on the road surface, and the wheel starts to slip. 3: When the amount of wheel slip exceeds what the software deems "optimal", the isolation valve is shut, and the caliper is isolated from the master cylinder, preventing any further fluid volume from reaching the caliper Iron: 1000 psi PCCB: 800 psi 4: When the wheel slip continues to exceed the software deems "optimal", the dump valve is opened, which releases fluid volume from the caliper into the accumulator. From the characteristic of the wheel speed behavior, the software calculates exactly how much pressure it wants to reduce (based on calibrations), and then opens the valve for just the right amount of time (based on calibrations) to let the appropriate volume out for the desired pressure reduction: Iron: 300 psi reduction to 700 psi, dump valve open for 7ms PCCB: 200 psi reduction to 600 psi, dump valve open for 5ms (Repeat step 4 if needed) 5: The wheel stops going into further slip, and starts to recover back to vehicle speed. Based on how fast the wheel recovers, the software calculates when it wants to start adding pressure back to the caliper, and how much it wants to add. This is done by opening the isolation valve for a short period of time, allowing fluid volume to flow from the MC to the caliper. The software then caclulates how long it needs to open the valve to allow the right amount of fluid volume to flow to acheive the desired pressure. Iron: 200 psi increase to 900 psi, iso valve open for 5 ms PCCB: 100 psi increase to 700 psi, iso valve open for 2 ms (Repeat step 5 if needed) 6. If wheel starts to go back into too much slip again, go back to step 4. OK, this is a VERY simplified description of how it works. But you can see in all cases, that the software controlled WHEN and HOW MUCH pressure to increase, hold, and decrease, and then the software determines WHEN and HOW LONG the valves are opened and closed to move just the right amount of fluid volume for the desired pressure change. " new parameters in pad application time, pad force, and point of activation" *can* be acheived by recalibrating the software And since amount of fluid flow is going to be decreased for PCCB, the HCU compmonents sized for the Iron brakes will be more than capable of providing the fluid flow rates requried. Cheers, Keith PS, Please excuse any typos above, as it's friday eveining and time to go do this...

Ok, where and how did you get that data??? It's not widely published! Or are you using "example" figures. Also - where did you get the data on friction coefficients on iron vs. PCCB?? I've done extensive searches and been unable to get verifiable, repeatable data on this! From Bosch I can only get the following: pressure bleed pahse @ 20 ms, and buildup (in steps) typically @ 200ms. If indeed your data is correct, then does not the issue of a slow pressure build up in the brake cylinder become an issue bc the the deceleration switching threshold would not have responded? Is not the size of that unit (pump capacities, etc) a mechanical issue??? Remember that fluid must be pumped back into the resivoir - if it's (fluid) stays in the accumulator, then pedal pressure will drop as the system cycles. I'll have to dig it up, but I seem to recall that some (not all) Bosch systems separate the brake booster from the ABS unit (it's been some time). PCCB is, no doubt, still not fully sorted out. Sounds like "we're" getting there, though! Enjoy the beer - I'm having a very well shaken bit o'syrup, ice, mint, and a very good burbon - perfect for an incredibly humid evening!! J

Just thinking out loud here, but perhaps the issue of PCCB durability is related to the pad release time. May sound crazy, but it would be great to see the friction data and the precise ABS control cycle chart. Simply put, can the standard system get the pads off of the rotor fast enough? Would have to have mighty big outlet valves then (to reduce pressure more quickly), and a larger accumulator (to reduce the pulsing force)..... Thoughts??? Or is this julep just getting to me??? J Darn it - looks like rain. So much for a nice evening outside.....

JeffES, this is a good question, as the P90 pads with my cast iron rotors do feel much stickier than with the stock brake set. I could see this also being a problem with the ceramic tendencies and extreme temps. The hammering and high temp fusion between the pads and rotors causing the failures. Ever see ceramic parts fuse together at high temps? Instant fusion, this could be some of the problems, not enough gasses in between the pads and rotors maybe causing the problems also along with heavy handed hammering of the ABS. Maybe Porsche may have to try dissimilar type compounds, as the P90 pads have ceramic compounds. I would think the rate of speed maybe more of a question of Pad compound and make up, or the ABS cycling.

oak, stephen we just checked my brakes at 6,000 miles after 3400 mi of heavy brake high speed trips. they are perfect

Jeff, The pressure I used in my "ABS Cycle" were "example" figures, just trying to illustrate how different calibrations in the software can leade to different amounts of fluid being dumped and re-applied. WRT to CoF for Iron vs. PCCB, I don't have any data, sorry. Porsche or Pagid are most likely the two places for that, and I doubt they'll spit it out. The timing of ABS activity is highly variant on what surface you're on, the rotating inertia of your wheels (and brake rotors), and then the effectiveness of the ABS algorithm and calibrations. WRT to GMT800 data, well we'll just say that its not available on the internet Can you expound on "then does not the issue of a slow pressure build up in the brake cylinder become an issue bc the the deceleration switching threshold would not have responded?" ? I dont think it's an issue at all since PCCB brakes with higher friction and lower rotating inertia should require that less fluid needs to be returned to the cylinder in the same amount of time. I'm not sure what the "deceleration switching threshold" is, is that Bosch/Porsche ? Pumping is also not an issue, since less fluid is being dumped and re-applied, the pump has a lot less work to do than with iron brakes. You are correct, most Bosch (and all other suppliers) units have separate brake booster, MC, and ABS unit. There are always a few units which try to combine them together for packaging. Also now, a lot of systems are using the ABS pump to provide additional "emergency boost" in panic situations. WRT to trying to release the pads off the rotor faster, it's a good brainstorm, I hope the mint Julip was good However the goal is never to completely release the pads off the rotor - its just to reduce the pad force to a level that the wheel will be slipping at an optimum amount. During ABS the pad should stay connected to the rotor the whole time, its just the force that holds it to the rotor that varies. Again due to PCCB higher friction and lower inertia, it should take less fluid release to recover a spining wheel than the iron brakes. The net effect is that using the same HCU, the PCCB system will be able to reduce braking force faster than the iron system. If you completely dump enough fluid out to let the pad off the rotor, then you're not braking that wheel any more and you'll lose a lot of stopping distance. That's not what we're trying to do. Sorry for the rain, it was drizzly here too, at least the hefewei�en was good Cheers, Keith

FWIW... I looked closely at the PCCB brakes while at the Leipzig facility for the CarreraGT day. Both the TT and the GT2 (along with the CGT) were equiped with the PCCB brakes and the green pads. There was no one rotor that looked to be in bad condition, and that was after several groups before us.

As time goes by, both the production of the discs and the ABS system will change, and wear issues will be solved. The earliest adaptors are of course, the "pioneers". J PS - HT - your flow example is way off. If you read the post, I'm referring to flow rates, not absolute pressures. Do you not realize that perhaps the standards of ABS systems (pad pressures, rebound rates, etc.) ARE part of the CCB issues?

Hi Sloth, That Turbo rotor looks pretty good. It looks basically like my second set of rotors looked when I initially got the car back from PAG (I suspect they weren't totally new � the originals were completely smooth when I got them). I would term that normal wear levels. But compare that to the photo of my own first rotor. The only thing I'd point out is that the patches of darker and lighter areas. That's transfer from the pads. So the pads have been warm in the past. I�d be interested to see the condition of the pads. I think what all this comes down to is that there are just different styles of brake usage. We know that even on the track two drivers who have equal times will drive in different ways and will make different use of their brakes. I know and freely admit that I'm hard on brakes. Part of this might have to do with the fact that I've been driving around Europe in a relatively carefree manner with diplomatic plates. I�m not alone. I�ve heard lots of stories from others. My friend Ulf was getting 10 laps out of a set of pads at the N�rburgring in a GT2. Ulf is a amateur racer and has a reputation for being fast and competent. Some people here seem to be taking it as a matter of pride � that they are somehow being accused of not being fast if others are having brake problems when they are not. I don�t think that is really right. I think it is possible to be very quick without being hard on your brakes. It is just a matter of style. In fact, maybe the fastest among us are the ones that don�t overuse their brakes? Stephen

Stephen, I agree with you... that turbo rotor is a far cry different than the photos you posted earlier. All the cars equiped with the PCCB's had the green pads, and they all seemed to be in pretty good shape with a lot of life left on the pads. These cars have also been run for the last few days at the Leipzig test track by a few different drivers. Granted it is difficult to tell just how long those rotors and pads have been on the specific car, and what the car is being used for when not being tracked by CGT customers. The brakes on CGT 's looked the same in terms of wear and they were being driven by the engineers as well as the factory race drivers Sasha Massen and Timo Bernhardt. Like you say... different folks and different driving styles.

Hi I am new to the Rennlist and a little late to this thread, but I find it very very interesting! Oh, and hi Keith and FixedWing! I have a GT3 RS on order and am considering ordering the PCCB... Naturally this thread is making me think long and hard about it... What I wonder is this: 1) What is the chance that some of FW's problems are related to the PSM? I.e. how many owners of GT3's with PCCB have had these kind of problems? 2) To what extent is the problem mitigated with the Green racing pads? 3) To what extent does the lower weight of a GT3 RS help the problem vs the heavier TT or GT2? 4) Given that my brake components tend last longer than other peoples, how much will my "gentler" braking help? 5) Finally since these systems are in continual development, will a brand new GT3 RS to be delivered late this year have better components? In other words will the combination of the above factors be enough to mitigate the problems and I should go for the PCCB? In response to Keith: no I don't want PCM at all. I wouldn't pay a cent for it and quite enjoy that my current GT3 CS (mk2) is a "pure driver's car" so to speak. I simply don't want the interference of it. That's why I don't like the Ferrari 360 but prefer the 355, that's why I stopped looking at the Gallardo when I found out that is has ESP, ASR, ABD, ETC, ETC. These cars are fantastically capable - but I want to do the driving! In fact I don't even like the ABS! I know it is way better in the rain as a safety device, but I hate the interference. On the old 968 it was so old and crusty that it almost never did anything. But on the new GT3 I have on a number of occasions, both on road and track, experienced the equivalent of brake fade from the ABS. In sudden or hard stops (or on bumpy track?), the car suddenly takes much longer to stop and I loose feel in the brake pedal. Very scary and very unpredictable. On a dry track I would much prefer to be able to feel the car start to loose traction and adjust the brake pedal pressure myself like I would in a race car. That gives me the control I want over the car. Maybe my ABS system in the GT3 isn't working properly, but it certainly hasn't impressed me those couple of times when I almost went into a car in front of me or almost went off the track. Anyone else have similar experiences? Thanks, -Christian

I think we need a new anaolgy for PSM: Rather than think about it as a driver aid intent on reducing your driving pleasure, think of it as a condom. When using it on familiar ground, say a wife or regular girlfriend, it may interfere a little but it can prevent undesired consequences. When using it on unfamiliar territory, it can save your life. That wasn't too crude now was it?

Good one

It's not a "PSM" issue, but it does seem to be an ABS issue. Just a guess here, (based on earlier items) - since the friction levels are similar (in none of my PCCB literature is there mention of shorter stopping distance(s)) to the iron brakes, perhaps the tendency of the pads to "rest" on the rotors during the "pulse" is causing some of the wear issues. I've heard (and made) some of your comments on ABS when driving on a rough track (Sebring). When a tire is "airborn" as long as it can be on such a track, it's easy for the pads to stop the wheel, thus pressure is released. Trouble is, that's the moment traction is regained - so the system has to play "catch up", and this leads to some interesting pedal feedback. The PDE, when at Sebring, had many issues with the ABS/PSM interface in dealing with the rough surfaces there. For track use, I would like to see an "off" switch - IMO. J

I'm still trying to decide whether to order PCCB on the GT3 RS. And I'm still confused. And I have to choose soon! Has anyone other than FixedWing had problems with the PCCB? If so, what was the car and the circumstances? Thanks, -Christian