TR6

First, I would never take a car on the track if I didn't know anything about how old the brake fluid was or what kind it was. Hindsight of course, but first thing would have been to flush the brake system BEFORE taking it to the track.

I cooked my front street pads this weekend and had to pit in early but I was driving a BMW instead of my 911. In my case, it wasn't the fluid that got hot. The pedal was still firm. My problem was I made the mistake of buying Axxis Ultimate pads and thinking I could manage them on the track. Wrong. They are very good on the street, but once you exceed their mean operating temperature on the track, the pads just glaze over and start disintegrating. I was lucky that I was able to buy and install a new set of PFC 01's at the track and still save the remainder of the weekend. For what its worth, the PFC 01's also seem to be doing well on the street so far! They are definitely more aggresive on the rotors, though.

PorscheZen

VERY VERY IMPORTANT: BLEED YOUR BRAKES ONLY WITH A PRESSURE BLEEDER. NEVER "PEDAL" BLEED BRAKES ON A 964!!! Otherwise you will ruin the seals inside of the master cylinder (ask me how I know!).
Second: REMOVE THE BRAKE ROTOR BACKING PLATE ON YOUR FRONTS FOR ADDED COOLING.

chancecasey

Interesting. My car was probably lighter (2950 with 3/4 tank of gas) and the ambient air temp was probably cooler (60F), and this was 4 days of Laguna Seca (not a particularly fast track). Good info to know, though, so I'm glad I'm stepping up to SRF. I would not consider ATE blue a real race fluid - I have heard of several race pads boiling ATE blue on street cars at the track.

TR6

Another thing that some less experienced track drivers do (myself inlcuded) that can generate more heat in the brakes is to brake too early and stay in the brakes too long. Braking too early and then continuing to apply braking, even at a reduced force, for a longer distance will generate more heat than braking harder, but for less distance/time. At least that's what I've been coached. I was told that its not uncommon for newbies to overheat their brakes by dragging on them longer than they should. I have not yet overheated the fluid in my 964 (I flush them religiously), but I've definitely toasted some pads...

SimonExtreme

This is so true. Within the limits of good driving technique, short and sharp is better than long and drawn out. I also believe that the better (more agressive) the pads, the quicker you stop and therefore the less you are on the brakes. This actually helps brake temps.

Bill Gregory

This is not a generic 964 issue. Any car with tens of thousands miles and years on it's brake master cylinder will rip it's seals if the brakes are bled by pushing the brake pedal. As I recall, Porsche even cautions against this in the 993 workshop manual.

Bull

Most brake pad manufacturers have a section on their website where they give the temp heat ranges for their various pads, along with other data. For heavy cars like 964s and 993s, you need a pad with a heat range that goes to around 1600 degs on the high side. Most of the entry level pads, like Hawk Blue 9012s and Pagid Orange have high end limits of around 1200 degrees (from memory, no charts in front of me), while Hawk HT-10s and Pagid Blacks have high end limits of 1600 degrees (memory again). I found that with my street cars I toasted Hawk Blues and Pagid Orange pads. Not so with the HT-10s and Blacks.

BTW, I have never had a problem with ATE Blue changed every 6 mos with bleeding before every event. (35 days/year).

donoman

What if I went to Pagid Black fronts and Porterfield R4's for the rear and swapped out the fluid?
Does removing the backing plate really help cool things down?

After looking for rear calipers it seems like they are going to cost me an extra $300!? Ouch. Not to mention the 100$ proportioning valve.
I'm not sure I want to put my next $400 into rear calipers; especially if I can learn how to drive around it by practicing quicker, shorter braking like you guys have described.

boxsey911

Having just bought a pair of rear calipers (from a 928 S4) off ebay, I can confirm you're right about the costs (£250 for me). In addition to those costs are a set of Pagid pads (£100) and a complete brake flush (£20). Add in the cost of re-newing the brake hoses (£50) (might aswell while the calipers are swapped) and my total is coming out at about 420 quid (approx $850) to do the upgrade.

However, after my own episode I don't think the rear pads are good for more than two trackdays (it's only possible to get OEM or Textar over here for the two pots). Add in the cost of extra fluid flushing and the cost per trackday soon adds up. I figure that over time the new calipers will pay for theirselves as I would expect to get 5 or 6 trackdays out of a set of the larger pads (especially since I have more choice now). Worth more than that though, is the confidence that I'll have in the car's brakes while driving round the track .

pat056

You said you inside bleeder was weeping? Here's what I would do:

1) Replace your bleeder(s). At least the one weeping. It's only a few bucks and very easy to do with a power bleeder.
2) Flush your brakes, not bleed, flush. I would drop the level down in the master cylinder w/some type of suction device (I use a turkey baster). Fill it back up w/new fluid, attach power bleeder w/new brake fluid(I use ATE Blue or amber and have raced a 964 for years w/o boiling the fluid...personal choice), and flush at each caliper until you know it's fresh fluid. I would expect to use 2 cans of fluid to make SURE.
3) See if there's some way to get more cooling air to the brakes. I have brake ducts.
4) As far as pads? There are good track/street pads out there that can do a pretty darned good job. Hawk HPS comes to mind. It depends on how much you're going to track the car IMHO.
Make a note to yourself to flush brakes at least after your 2nd/3rd DE. It just takes minutes and ATE Blue is $10-12/can.
I think 75% of your problem was old fluid.

joey bagadonuts

Here are a couple of sources:

OG Racing
RACEShopper
Pegasus Auto Racing

Unfortunately, not all items and corresponding prices are listed. RaceShopper usually requires a phone call BUT they're very competitive.

dfinnegan

Joey, thanks very much!

joey bagadonuts

You're welcome. I also added Pegasus while you were responding--outstanding service and price!

joey bagadonuts

I don't know if this is entirely necessary. I actually gutted my proportioning valve as outlined in one of Garrett376's Want to know what the inside of your (fill in the blank) looks like? threads.

I tried out the modified valve over a four-day race weekend and had no issues. The difference in handling compared to the stock PV was negligible--and I'm talking about hard braking at high speeds. Like Garrett, I have a big brake set up on my car which utilizes a smaller rear pad/rotor than in the front ... kinda' like a stock 90 C2.

I haven't looked closely but Garrett confirmed that the pad wear rate evens out, i.e. it's no longer 2:1 or 3:1 front to rear, more like 1:1. Of course, you'll want to be careful the first time you try this out. I don't anticipate any issues but safety should always be your primary concern at the track (or whenever you get behind the wheel) so proceed with caution.

springer3

If the rubber brake hoses are original, it is time to replace them. The inside lining can get soft (spongy pedal), and it can swell. I have seen German brake lines swell to the point that pressure is maintaned in the caliper after your foot is off the brake pedal. Brakes overheat in the extreme case. Changing fluid types can trigger problems with brake lines and seals conditioned by long exposure to one type of fluid.