Kilomph

I attended AMR PCA at PPIR earlier this year, two day event with the second day nearly getting rain/snowed out with zero braking issues. One PCA auto-x and now a weekend at Pueblo Motorpark which is a seriously fun track.

Brand new pads/fluid in 3/14, fluid was Castrol SRF. Brakes were fine until Pueblo, first day they were fine with the instructor, second day I solo'd and my first session out they boiled right at the end of the run, nearly banged into the car in front of me parking in the paddock. Pads/brakes were smoking, too. I drove around to cool them off before parking.

Talked to a couple instructors and turned off PSM, took it a bit more slowly the second session, pedal got a bit mushy but never lost brakes. Third I went a bit faster, 120 down the main straight and the pedal dropped to the floor, pumped and scrubbed the speed off around turn 1. Coasted in and corner worked the remaining sessions.

I just started doing HPDEs this year, not to toot my own horn but I've been told I'm a natural, still completely novice but am able to carry a steady consistent pace around the track. I'm just confused as to why my brakes overheated, I didn't think I'd be able to do that for another season or two which makes me think it's a setup/mechanical issue.

Was the fluid too old? Colorado is rather dry, not much moisture for it to absorb. I doubt the auto-x got it too hot, 12 55 second runs. I know once it's boiled it's compromised and my mechanic said to just bleed before each event, possibly bring fluid/bleeder with you to the track incase it happens again.

S04 Pole Position street tires. Ordered Motul 600, GT3 brake ducts and a power bleeder. Considering Pagid Street pads, too (was the smoke emanating from the brakes my pads?). Any ducting available for the rear brakes? SS brake lines?

Any other tips? I know I'm over braking at points and not carrying enough speed but nothing out of the ordinary for a new driver.

LexVan

Who did the new fluid on 3/14? I'd look there first. Might not have been done properly.

Kilomph

I'm sure it was done properly and with SRF. Very reputable place with Spec Boxsters.

bernb6

I'm a little surprised your instructors let you go out again without bleeding your fluid after the first boil. As your mechanic said, once brake fluid boils, it's not the same.

You didn't mention whether front or rear brakes were overheating - I expect you have discolored calipers somewhere. PSM will certainly get the rear. If the front (and you have GT3 ducts), you may simply be overbraking, as you suggested. Thin pads could exacerbate heat transfer into the fluid.
If you're running with Harrys track timer or similar, check your end of braking speed versus actual speed in the corner. I was in a very similar situation to you (boiling front once and rear once (forgot to turn PSM off)) and realized I was overbraking by 10-15 mph.

Re the smoke, yes, it was likely the pads. When you go to higher performance pads, be careful to bed them as recommended by the manufacturer. Re ducts for rear brakes, yes there is something available, though they need a little modification: I think they are 996TT's (http://www.planet-9.com/987-cayman-b...s-non-gt3.html)

In the end, I think it will be your braking technique that will make the difference. OTOH, until you resolve that, you do need to be sure of your brakes' capability to shed the heat you're putting into them.

Kilomph

The instructors said the same thing to me regarding it being compromised and that I should just go slower and keep PSM off. I was fine and kept it in the back of my mind the whole time and pulled off the track accordingly.

Thanks for the rear ducts link, just what I was looking for. I'll look into Harrys track timer.

bernb6

One more comment: radiated heat from the brakes can soften the adhesive on the wheel balancing weights so that they move or come off. You can use metal aluminum plumbers tape (Home Depot) to cover the weights and reflect the heat away.

Ubermensch

I agree that you're likely over-braking as you learn, but that doesn't solve your problem. What pads are you running? You mentioned they were new, but not what brand or friction level. I've found that going to slightly better pads made a world of difference in the amount of braking I had to do...which reduced the heat transferred to the fluid.

-Shawn

the_vetman

OP, something is wrong in your system. Unless you're doing something dramatically wrong, there's no way you should be boiling SRF fluid (pretty much the best). 70 DE days with heavy, repeated braking on OEM, Super Blue, and Motul 600 fluids here. PSM on for a long time then PSM off. No boiling ever. I do have GT3 front and 996 + 997 turbo ducts in the rear, but did many days even before those went on.

Crucial: what pads? Stock or high friction pads (e.g. Pagid Black) will lead to high heat build up. What were ambient temps? I wonder if one of your pads is dragging (caliper issue).

BTW... as a novice there's no way you're going so fast (trust me on this) that you're boiling the fluid.

Kilomph

"BTW... as a novice there's no way you're going so fast (trust me on this) that you're boiling the fluid."

Well that's what I was thinking, it didn't make any sense to me.

The pads are OE replacement, nothing special and I don't know the brand off hand right now. The same place that put the SRF replaced the pads as well. They recommended Pagid Streets at the very most due to excessive rotor wear and me still being a novice.

I'll take a closer look at my calipers/rotors tomorrow to see if any one was discolored due to dragging.

Ambient temps were in the low 90s .

the_vetman

OEM/replacement pads could be part of the problem. Those things can require a lot of braking to slow the car down, leading to increased heat build-up over time. I suspect there is more to it than that, but no one knows at this point.

terbiumactivated

I suspect there is more to it than that, but no one knows at this point.

+1 if you can't get it done with Brembo brakes (assuming they are functioning correctly) then "more to it than that" is a given.

sjfehr

Brake fluid is very hygroscopic and will pull moisture straight from the air, even in "dry" climates, it doesn't need to be humid enough to condense. It should be changed annually; more often if you're tracking. High temp racing fluids are even more sensitive than standard street fluids, but SRF less than most; even in humid climates, you should NOT have had an issue. That said, Castrol SRF is like $70/liter and way way overkill for this application, and not something I would expect a shop to recommend, especially considering what they told you about pads... is that what you paid for, did you see the bottles, or there a chance you actually drove on many-years-old fluid?

You're not left-foot braking and riding it slightly, are you?

Kilomph

The shop I used is 100% reputable and I can't say anything bad about them, most guys at the shop track their cars as well and like I said they have a couple Spec Boxsters that they rent out. I was very surprised when they said they used Castrol SRF and considering a full brake job was done in March I'm only left more confused now. I guess there's a chance they just replaced the pads and didn't flush the brakes but considering their reputation I highly doubt it.

All the calipers/rotors look the same and I don't see any strange discoloration. I'm not left foot braking, I am trail braking and over braking.

I'll freshen everything up and add a little more air flow, we'll see what happens at High Plains the end of this month.

Thanks for all the replies.

Ubermensch

Adding air always helps, but I would certainly consider upgrading the pads. I used stock pads for several DE's and then was surprised at how much better the Porsche sport pads were...then a year or two later I went to PFC pads. I couldn't believe how much less braking I needed to do. The first session out on the PFC's I nearly locked up the brakes because I was used to applying so much more braking pressure in a particular section. Less braking=less heat.

The same is true for your learning curve as a driver. I'd suggest doing track walks to understand the actual camber and elevation changes. When you see the terrain up close it will click that there are a lot of places you're probably braking that don't require it. In my experience that's why new drivers tend to be harder on brakes than experienced drivers.

-shawn

orthojoe

Pad shouldn't cause the pedal to drop to the floor. The fluid is boiling over for some reason, but the question is why? They shouldn't boil over that easily, especially on street tires.