Only have an RS 60 with PCCBs but had a soft peddle yesterday with a spirited drive over Sonora pass. I have driven in the mountains for years and usually easy on brakes, however I was purposely breaking into corners while descending just because these are so good and thought they should take it. Never rode the bakes at all. Just corner breaking.

Peddle remained soft all the way down until I pumped them once and it seemed to come back. Actual breaking never reduced, just a soft peddle.

I was guessing, moisture in the break fluid. Is this possible?

Car was built in Feb. of 08 and has 4700. After they cooled down, all is back to normal.

 

Sounds like you'd benefit from a fluid swap; try ATE Super Blue.

 

I have about 25K total miles and maybe 25 track days.

But this was not a "wore out" issue, I overheated the brakes and cooked the internals. This happened in a single day on all four corners.

I ran the pads down to the wear sensors, which is bad for heat xfer (although you'd think Porsche would think of that when they decide when the wear indicator should get tripped).

If you have PCCBs and want to abuse them on track, I would suggest only running pads down to 1/2 to 1/3 thickness, which kind of sucks because they are hard to change, and you could easily go through >50% of pads in a two-day track events.

 

Thanks for sharing your experience. Just trying to learn something here. So in this case the problem is NOT related to what brake fluid you are using right?
Reason I asked: I don't understand how using better brake fluid would prevent what happened here, which is excessive heating of the components from lots of braking.
Does the brake fluid participate in brake cooling in any way?

 

As I noted above, the brakes never got soft or otherwise complained. As such, I don't think it had ANYTHING to do with brake fluid.

Similarly, I don't think brake fluid has anything to do with cooling. I think brake fluid "goodness" comes from having a high boiling point.

One minor exception: since brake fluid was squirting (in small volumes) around the seals and vaporizing on my pads, I suppose the brake fluid was HELPING with cooling, but I wold not recommend this particular brake cooling technique.....

 

I am comtemplating on doing the same with drilled rotors.

Has anyone got feedback on how the brembos feel compared to stock? Is there really a big improvement?

 

I will report back after I get some track time, but around town they feel less "linear" under mild braking. By that I mean a slight input will not produce much braking, but then you get some "bite."

They seem pretty linear under medium braking.

It will just take a bit of getting used to, I think. I really LOVED the PCCBs in terms of feel, but I need to live with the Brembo GT setup for a while, including some hard braking before I give an informed opinion.

Note also that I have the race pads on, which I am sure is contributing to the progressiveness of the brakes (or lack thereof) in street use, especially when not up to proper operating temps for those pads.

 

would love to know how the pccb equipped cars at PSDS are making out, and what kind of wear/longetivity they're seeing.

 

The stock fluid has a relatively low boiling point compared to some of the better racing fluids, such as super blue. I think that is where your issue is, you basically boiled your fluid. When the fluid boils, everything starts to overheat and melt, the viscosity changes and it starts leaking around seals. I've done it myself, very easy to do at a 'momemtum' track like limerock with a lot of cornering and braking zones.
Moral of the story; fresh brake fluid flush once a season with a good hi temp fluid.

 

Wait until you take yours to the track a few times, esp a short track, then really carry some speed into the corners with some heavy braking...you'll see what I mean, it will become very clear!
Having 15" brembos with stock fluid would have the same result at the track. Heavy chevy is right, the pccbs won't show any signs of overheating for a long while, nature of the beast.
Unless you drive in the green run group, anybody taking a relatively heavy, hi hp, awd car to the track, like a 997tt, def needs some decent brake fluid.
Chris, the psds cars all run the super blue fluid, they get a lot of life outta their pccbs.
c

 

Good to know. I thought I read somewhere that the folks down there said they have been bullet proof. Not saying they're not being honest, but you never know

Plus, they see the full gamut of drivers there from rookies to very good, so those brakes are having everything thrown at them.

 

Chris,
Thanks for the helpful info & explanation. It makes sense.

 

Since I like to track my GT3 with PCCBs, I only use Castrol SRF. I run at Carolina Motorsports Park and VIR for the most part. CMP is known for being hard on the brakes, even with the new configuration. I've never felt any brake fade, or had any negative brake experiences using my PCCB's with stock pads. I do, however, change out my pads whenever they get less than 50%. A heavier car and different driving style can dramatically change these results.


I'm not sure if there is better brake fluid out there or not, but I'd try to use the best fluid you can. A bottle of SRF costs around $75 which is really a small amount of money relatively speaking to the cost of your PCCBs.

Best of luck.

Dan

 

What sort of lap times were you running?

It seems as there is quite a bit of "extreme" over-braking since turn 1 is a much higher speed corner than 85MPH (experts confirm?), and the back straight is faster too.

Guys like Pobst can run that track with ceramics all day long and no problem.

If the above is true, it would appear operator error (significant over-braking) is the basic source of the problem (not the type of brakes or fluid). It further suggests that all that extra HP to get to 142 MPH is wasting brakes (and therefore wasted).