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Discussion Starter · #1 · (Edited)
I recently converted my PCCB equipped Boxster (aka Cayman Cabriolet) to Girodiscs.

First of all, BIG thanks to Craig at Rennstore!!!

I have had brake problems from day one with the PCCBs. On the street they are fine and on the track they aren't. Somehow too much heat gets into the calipers and boils the fluid causing no to low brake pedal. It may be my braking technique, although not a single instructor has said I was doing it incorrectly. After a few code brown moments, however, one loses one's trust in the car slowing at the last moment and one then leaves enough time to get in an extra pump or two to get a brake pedal back.

So, is that PCCB or not? I don't know.

What I do know is that, even from Suncoast, a replacement set of PCCB rotors costs $16,500. So if you wear one or more out, pick up a pebble and crack one or whatever, that's just too worrisome for me.

Craig let me know that Girodisc now has a set of rotors that are the exact replacement for Cayman/Boxster PCCBs. I won't state the price here, you need to contact him for that in case he has a sale on or something, but let's just say that you can buy all four for less than half the price of a single PCCB rotor.

And these are very high quality units. Heavier than PCCBs? Yes. The rears not as much as I would have thought. The fronts are pretty heavy -- remember, they are 350mm diameter and 34mm thick.

Replacement was completely straightforward so there isn't any need to go into all those details here. A bit of searching this site will reveal how to go about it if you don't already know.

How do they feel? Great so far. I am starting with a new set of street pads. I think I can feel the extra weight in the front, but just barely. And I know that feeling will go away as I get used to them. Braking effort is virtually indistinguishable from the PCCBs.

In a couple of weeks I will change the pads to RS29s for the LSRPCA DE on May 1 and 2. At that time I will clean the rotors of the street pad material and properly bed in the new ones. I know a DPS officer who will (he says) keep me out of the pokey as I bed in the 29s.

Oh, and I will run Ti shims behind the 29s and see if we can keep the heat into the rotors where it belongs. Maybe I can have real brakes this time!

I will report back with those results after the DE.

Thanks again to Craig at Rennstore. He is a delight to work with and a great resource.

I hope you find this of interest.

Best,

- Mark
 

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Also, I hope you flushed the stock fluid and put in high temp like Motul or SRF prior to this endeavor. I've had a good amount of track time with the pccbs and have never had an issue with the proper fluid and the motorsport pad.
 

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Discussion Starter · #4 ·
Ken,

Yes, I am using the stock calipers. So now the car basically has GT3 brakes and iron rotors. The ceramic rotors are in boxes above the shop office area. If I ever sell the car, the next guy gets a choice of rotor, albeit not for free.


RingSport,

I ditched the stock bug juice a long time ago. The last attempt at using the ceramic rotors was with SRF and even it would allow a mushy pedal after two or three laps. That is, mushier than it is all the time. (Why oh why can't non-GT3 folks get a real brake pedal feel? Please listen, PCNA! We like firm brakes, okay?)

So now it's Girodiscs, stock pads for street use, RS29s for DEs with Ti shims and Motul 600. Results on DE forthcoming after our May 1,2 event at TWS.

Best,

- Mark
 

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I'm thinking about making the TWS event too. I just need to find the time to flush the fluid and put on another set of tires.
 

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Mark,

What year is your Cayman Cabriolet? Was your PCCB the same as the latest generation? I 've heard Porsche has improved the PCCB from the first generation that they first came out with.
 

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Discussion Starter · #8 ·
It's a MY 2007 -- same everything as the Cayman S except I can put the top down...

and really hear that Borla SCREAM!!!

And yes, these are the second generation of PCCBs. The first ones suffered major degradation issues.
 

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I have had these 350mm 2-piece PCCB replacment rotors on my CaymanS Since Janurary. They are a well made, high performing product.
I really appreciate the folks at Griodisc for making them custom for my car. Glad that other Cayman owners are taking advantage of this great product.
 

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Discussion Starter · #12 ·
Hey I want those rotors too!

Err. Oops -- wait just a doggone minute! Yeah, I remember now. I already have them.

Anyway, considering the replacement cost just in case I ever were to sell the car and needed the OEM rotors, I don't see any way I could let them go.

There is that old saying about money talking and all, but it would take a lot to get me to do that.

Thanks for listening and for your interest.

Best,


- Mark

PS: A quicky update: The pedal still goes mushy (more so than usual) on the track after a few laps. A visit with another Porsche dealer yielded these suggestions:

1. Bleed brakes and use AP fluid.

2. Upload programming for iron brakes as opposed to the ceramic ones. (in the ABS unit, I guess???)

3. Report back...


So I guess we shall see.

PPS: I got a ride in a 2010 Turbo w/PDK. The car had GIAC, Champion intake and Tubi exhaust. Wow. Just wow.
 

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Discussion Starter · #14 ·
Mark,

How are you determining for certain that you are boiling the fluid?
The pedal goes mushier than usual. The only way that can happen is for heat somewhere to cause vapor to form in the system. The only source of heat I know of (unless the ABS motor can do it and I have never heard of that) is at the calipers.

And given that the front pads are cracked and the rears look like new tells me that it's in the fronts. I do know that front pad cracking is fairly normal. The bias is not adjustable and isn't controlled by the ABS, so I don't know what else to do.

I imagine that I need some braking pointers as I know non-pro/advanced drivers tend to use brakes to little and too long, but I haven't had an instructor, ever, tell me that I am so bad at it that it's my fault.

I did get a ride in a Boxster Spyder at the last DE that was driven by the Porsche pros from Atlanta. Damn! Those things are fast! But those guys could make my car a zillion percent faster too.

What they do is just nail the brakes really really hard and then get off of them.

I have gotten kind of gun shy about doing that in mine because I don't trust them to be there. After a few times when the pedal goes to the floor tends to cure one of really late braking...

Best,

- Mark
 

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I can pretty much guarantee that you cannot boil SRF in 3 laps unless you are doing repeated 150MPH to 0 stops.

Have you done the master cylinder test? With the car off, pump the brake pedal until it is firm, then press firmly on it and hold it for a while. It should not move to the floor.

Have you had the dealer check the brake booster system? There was at least on person on this board that had the same symptoms as you are experiencing and it turned out to be a broken part in the brake booster.

Mainly, my point is that you have a fault in your brake system that is abnormal and it needs to be fixed.
 

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Discussion Starter · #16 ·
I can pretty much guarantee that you cannot boil SRF in 3 laps unless you are doing repeated 150MPH to 0 stops.



I wouldn't think so either. But it does.



Have you done the master cylinder test? With the car off, pump the brake pedal until it is firm, then press firmly on it and hold it for a while. It should not move to the floor.




Yes, and it goes down but not to the floor. They (Porsche) say it's normal.





Have you had the dealer check the brake booster system? There was at least on person on this board that had the same symptoms as you are experiencing and it turned out to be a broken part in the brake booster.




To my knowledge, no one has checked that. I will be taking the car to the dealer for the next bleeding and will ask them to check it out. Thank you for that!




Mainly, my point is that you have a fault in your brake system that is abnormal and it needs to be fixed.



I know. That's why it's been back half a dozen times. They cannot recreate the symptoms on the street and aren't too sympathetic about track use. It's very frustrating.

Again, I appreciate the thoughts.

Best,

- Mark
 

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When they bleed it, ask them to note the following:

- For each caliper, how soon do the bubbles show up?
- Do the bubbles show up for all calipers? Is there a difference in the amount of bubbles between them?
- Basically, note the amount of bubbles and time it takes to see bubbles for each caliper in the order of the bleeding.
- Also note the color of the fluid as the calipers are bled.

If the bubbles show up immediately, and then stop soon, then I'd agree, you are either boiling the fluid, or there is breach in the caliper seals and letting air in. Also, if the fluid is darker or cloudy at first and then clears up, then it sounds like the fluid is boiling.

If the bubbles take a while to show up, then the air is getting in further up the brake system, like the ABS module or the brake booster or the master cylinder.

Good luck!
 

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My Girodiscs are actually coming off the car and the stock rotors going back on, I just can't take the pulsing vibration that I get from these any more. :) Once they come off I'll check for warpage and see if I can't pinpoint the problem, but it has gotten to annoying to ignore... I also didn't find any difference at the track really with the Girodisc's either other than again the pulsing and vibration that occurs which doesn't install a lot of confidence and is distracting at times. Maybe I got a bad set or maybe I'm hard on them I don't know, but time for a change...
 

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Mark, how is it going for you? Ken, you adopted a very early set + appear to have pad deposit issues.
I sent the rotors back to Girodisc and they resurfaced them and checked them and said they weren't warped but they weren't sure what was causing the vibration, so I have a cleaned up set in a box should I want to reinstall them, or I might sell them, I haven't made up my mind, heck I've only had 1 track day on my factory replacement rotors to date so it isn't like I've needed something more at the moment. :)
 
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