jiturbide

I currently do club racing with my 996 porsche carrera. But after two or three laps of really pounding on the brakes the pedal gets really stiff to the point where for a second the brakes do not work. REALLY DANGEROUS!!!!

I tried disconnecting the abs and tried the brakes with out the abs system and the brakes work reasonably well and the failure disappears.

Since I bought this car, the traction control sensors where not installed but I do not think this has to do with the abs failure since it works ok some times and the failure suddenly appears.

We also tried connecting the computer to check in to check error codes but nothing comes up.

I am considering installing a dual pump with brake bias system and with a separate abs system but if some one can help me diagnose the problem would prefer to keep the original brakes.

Thanks to all....

Jose

Dennis C

Sounds very strange. Do you have OE rotors? What pads are you using? How old is your brake fluid? You say sensors are missing... this sounds like it could be an issue - the system isn't totally intact... any thoughts with that?

dnitake

Search for "ice mode". You're not the only one. I've had to pull the fuse as well. Didn't do it every time. The last time I left it in, I ended up 10 feet from a wall in the kitty litter. Cycling the brake pedal used to work, but over time has become less and less effective. Also had the dealer check it out w/ no codes. I checked w/ Reiser at PCA and he was stumped re root cause other than this is not a race ABS. A race version is expensive. Braking the old fashioned way is much cheaper. Good luck.

jiturbide

I currently use OEM rotors and change brake fluid every race. The sensors I am missing are the traction control sensors...

jiturbide

And I am using OEM Pads. Will buy som pagid pads from rennlist soon....

Hurdigurdiman

I would change all the brake fluid, pads, return the traction sensors. On fox news yesterday a Porsche racer had a real pile up and was very lucky to have lived. His brakes failed. Something you cannot afford to be altering in any way IMHO. Racing or not racing. Your life depends on the best braking system and I feel Porsche Engineers already had that worked out for you. Porsche winning track records prove that fact. You may want to check this site out on the ABS Porsche braking system. http://www.stoptech.com/technical-su...-brake-systemsGood luck

ECS Tuning

I had experienced this when the wheel speed sensor screw backed itself out at VIR. Very scary indeed.

TRT41

I could not imagine using OEM pads while racing... start with the simplest fix, change pads, and stop "pounding" the brakes. You might want to improve your braking skills, 996s are phenomenal to trail brake.
Post above changes, if you still have problems, work on the mechanical systems.

dnitake

> I had experienced this when the wheel speed sensor screw backed itself out at VIR. Very scary indeed.

Hmmm. Do you know if this threw a code?

>and stop "pounding" the brakes.

I 2nd TRT41, but...
There is the "don't do that" and use more finesse. Move brake pts back a bit or trail brake deeper and roll on the brakes rather than stabbing. Smoothness. All will help or eliminate the issue assuming you have the same problem I have. That doesn't belittle the fact there is the "ice mode" possibility waiting for you should you screw up and engage the ABS. It happens to me when I get a bit aggro and brake deeper/threshold on bumpy surfaces, even new pads and rotors. If you overbrake and bump right into the ABS, then watch out. Is this what's happening? If it's something completely different then "nevermind".

OEM pads for a race car. Assume R-comps? They won't survive very long.

There's a thread or 2 on this "ice mode" in the GT3 section (can't recall if it's 6 or 7GT3) if that's helpful.

jiturbide

thanks. what do you mean by ice-mode?

dnitake

Here is one of the threads:

https://rennlist.com/forums/997-gt2-...ly-got-me.html

jiturbide

dnitake: really interesting forum on the ice mode. Exactly what happens to me. Basically while I change the ABS unit to a racing or bmw unit I should be very careful with the brakes.
Do you think cleaning the holes on the rotors would help?

dnitake

jiturbide:
Cleaning holes won't help. Some great rotors don't even have holes. Sort of a throwback to the
days of out gassing.

If I recall correctly, pulling the fuse is annoying (effective) but you lose speedo. Does that happen to you?

An early double tap should work, but I keep forgetting to do it in prep for the real braking since it doesn't always happen mostly.

I'd like to know what you find w/ the other ABS units (namely do they really cost $10K).
No doubt they will perform as advertised. Please post.

jiturbide

OK. I will let you know if I decide to swith to a better abs unit. What specific fuse would you disconnect?

Hurdigurdiman

THis may help you in some way http://www.ehow.com/about_5580360_po...-problems.html