donoman

Hi Everyone,

2 days ago was the first time I brought my 964 to the local track (Thunderhill). In the morning I was taking it easy. This was my first time driving a rear engined car and I had a few butt puckering moments (coming from an E36 M3 and a well-equipped Miata) where I thought I was going to lose it but somehow didn't spin.

Anyway towards lunch I got the feel for things a bit and started heel/toe-ing and in generally braking much harder.

After lunch I drove my car on a mini-autocross course that the track organizers had been nice enough to set up. It was a set of slaloms followed by a sweeper followed by slaloms and finally a brake trap. I mention this because of what happens later.

Immediately after the autocross I took the car out onto the track and was driving around pretty well. I wasn't particulary pushing the limits as I had a friend riding with me and I have a tendency to spin cars or wreck motorcycles when my friends are around!!! (I've learned my lesson) ... Anyway I got black flagged due to car malfunction and the cornerworkers said they noticed my front left wheel was smoking.

Sure enough my pedal was soft and I was able to push it almost into the floor. Felt like I had a hole in the brakelines somewhere!?! Actually felt like I was bleeding the brakes for part of the pedal push, then it tightened up again (this is when the brakes actually worked - THANK GOODNESS - because I pitted behind a Ferrari and totally didn't consider what would happen if my brakes totally failed as I pulled up behind him!!!!)

Came back to the pits and sure enough there was some smoke, very light, coming out of the front left. I took the wheel off and it was extremely hot, way too hot to touch, and the lugs were super hot. Now, I've never taken a wheel off right after a track session so is this normal?? Anyway looking around I didn't find any fluid sprayed anywhere. What the heck. I noticed the inside bleeder was weeping a little but nothing serious. Checked it with a monkey wrench and it felt tight.

Let the car cool down and 5 minutes later the brakes felt solid again. No fluid lost from the reservoir.

Let the car cool down essentially 45 minutes and then took it out on the track for the last session... I took things slowly, about 50% and everything worked fine.

Now the questions:

1) What happened!
2) How can I avoid that from happening again!?

I am not sure which brake fluid I'm running (could be Dot3) as I just bought the car.
The car is running OEM Porsche pads & rotors.

Thanks for your help!!!

GeoT3

Donovan,
I think you boiled your brake fluid. You need to flush it...

George

Bull

First, I would change the brake fluid to a race fluid, ATE Blue, Motul, etc., and switch the pads to a race pad for track use, Hawk HT-10s, Pagid Black, etc. then I would investigate the left front caliper to make certain it is functioning properly and not hanging up so the pads don't retreat fully when you are off the brakes.

garrett376

OEM pads on a race track just don't work well - I'll bet your pads are now terrible on the street as well after getting cooked. Get some race pads so you prevent these issues, and get some better brake fluid. While it seems like a greater cost up front to buy separate pads, now you need new street anyways! A 964 is a heavy car, and the stock pads are not up for the task of a race track situation. Do a search for different pads that work well - PFC97's have always worked great for me and my friends who run 964's on tracks.

boxsey911

Like yourself I experienced my first brake fade this year and it really ruins the day. Like yourself I spent the rest of the day taking it easy but always worried I was going to lose them again.

Mine was almost certainly caused by using normal road pads that were 50% worn (I thought that would be OK but obviously not). Using normal Dot 4 fluid which had already been in for 4 trackdays (I thought it was fresh enough). I learned my lesson from this and flushed the system with Dot 4 racing fluid (equivalent to ATE blue) and put new pads all round (including Pagid blues on the front). The brakes were brilliant on my next track day.

Having looked around on Rennlist, it's also apparent that my standard 2 pot rears with their small pads are prone to overheating and boiling the fluid. This is further exacerabated by only being able to get road pads for them. So I'm going to upgrade to 4 pots before my next outing on track.

donoman

4 Pots --- from a 92+ C2 or any C4, right?

Yes losing the brakes is akin to losing your *****. I am just so THANKFUL that the cornerworkers caught me 3 turns before the 100 mph back straight!!!!

Rocket Rob

Yes, the rear calipers from either. Be sure to change the brake bias valve too.

4 pot bias valve (55 bar pressure regulator) part # 964-355-305-10

bgiere

Castrol SRF fluid and new race pads like PFC 01 or Pagid Yellows will improve things quite a bit....

donoman

Thanks everyone! I'll have this done before my next trackday (the pads & fluid for sure)... Maybe I should wear my motorcycle leathers next time out in case it doesn't work I can just jump out. hahaha

chancecasey

I never had a problem with ATE blue and Porterfield R4 for DEs. I will likely step up to Castrol SRF for racing.

I like the Porterfields for performance/price ratio - and they were one of the few folks still making pads for the 2-pot rears I've got.

Ritter v4.0

I was using Hawk Blues and ATE Blue, but Kinetic highly recommend Castrol FWIW.
Its amazing what stopping power those little calipers have with the right fluid/pad combo.

dfinnegan

Garrett, would you mind sharing where you source these pads?

Thanks,
Dave

LouZ

Wow, I'm totally opposite! I never had a problem with fade using OEM pads even with 2 pot rears (with ATE Blue). I switched to Porterfield R4 because they were available for the 2 pot rears. I lost my brakes! Last winter, I switched to 4 pot rears and bought new Porterfields to match - same problem - fried the brakes! Plus, I run thru a full set of pads in 1 DE event (3 days).

I find that I'm not boiling the fluid - I'm exceeding the pad temp range and get no bite (pedal goes down, but I still brake, just long).

I'm switching to PFC97's since I now have 4 pot rears.

Bill Verburg

It's not brake torque(aka stopping power) that is the issue w/ any 911/964 oem brake setup. But rather heat management. The proverbial boiled brake fluid described here is classic.

To avoid it w/o a bbk you need to lighten the car as much as possible, avoid using the brakes as much as possible, use fresh high temp fluid, use pads w/ an operating tepmerature range appropriate to usage and duct as much cooling air to the fronts as possible.

another step in the right direction is to use 30/34 rear calipers from a 993. This takes some of the thermal load off the fronts. Some may not like the extra rear bias but most do seem ok w/ it.

donoman

Man, how much is all this going to cost me!?
How do you duct more air to the brakes? Are you guys talking about those foglight replacement things? Where can I buy those?