Carrera GT

I'm wondering if there's a factory or aftermarket pad, or if anyone has figured out an aftermarket rotor and pad to take the 991 to the track.

Any clues?

fbroen

Brembo 380 BBK installed by SM_ATL, here: http://www.6speedonline.com/forums/9...ournal-32.html

chuckbdc

Why are they needed? Are the stock 991 base or S brakes a problem at the track? If so how? Are they more expensive to replace than the Brembos?

The only thing I have seen about 991 brakes at the track are that the rear pads get cooked due to the electronic assist given for stabilization or turn in.

Is there more to know?

Carrera GT

In a 3000lb+ car, there's always the consideration of better brakes. I haven't seen the rears suffering and both front and rear seem to be significantly upgraded from the 997 -- I'd say these front calipers could be better than 997.2 GT3 and RS.

Expense and operating costs are always an issue -- aside from tires, it's brakes and rotors and that eat you alive at the track -- my primary thought is raw performance in terms of peak braking effort, pad feel, heat and fade.

Carrera GT

Thanks for the reminder, I'd forgotten about that owner/car -- I dismissed the "upgrade" as more of a "retro-grade" because it's a generic kit adapted to the front of the 991.

If the 380mm fronts are the same thickness as the factory rotor, I'd be tempted to space out the factory caliper (assuming dimensions, swept area, annulus, etc. are compatible.)

chuckbdc

I fully agree- thus my questions.

When I was doing serious tracking I changed pad and bled brakes per event and replaced rotors seasonally. But everything was way more straightforward without the computer participating!

John's 991

I am pretty happy with the brakes on the 991 on track use, but noticed the pedal getting a bit soft after several hard laps. I am going to flush and replace with racing brake fluid (looking at the Castrol with a 500 degree boiling point) to see if that resolves the problem. I might look for a slightly more aggressive pad, but not something that will destroy the rotors.

I would be interested if anybody has experience or recommendations on different brake pads that fit in the OEM calipers.

97c2s993

I will post my experience with my brakes: at the end of May I took my 991 to Watkins Glen for DE. I was in the White group as this was my first ever time at any track with any car. I had a good instructor who helped me progress rapidly - so much so that in the PCA log book in my first entry he recommended a move to Blue group. I don't mention this to brag but to say I drove the car really hard and exceeded 130mph on several occasions. By the same token I used the brakes VERY hard - when the instructor told me that 'your brakes are your friend' and used an analogy that 'if the ABS doesn't engage then you're not braking hard enough' (exaggerating to make the point) I literally hammered the brakes on entry into turns.

On my way home to NYC that evening I noticed that the pedal had gotten softer (I never lost the pedal during the sessions), but more importantly on braking I felt a grinding (not pulsing) every time I applied the brakes that was bothersome.
I took the car to an independent Porsche mechanic who confirmed I did not warp the rotors but he told me the pads and rotors got so hot that parts of the pad had fused onto the rotors resulting in the grinding - or lack of smoothness in braking. In the meantime he bled and changed the brake fluid to hi-temp fluid. He told me that the issue may persist and if it did, I was planning to return to the dealer (see if they'd do something under warranty as the car had just 2k miles on it).
Then, when driving 7 hours coming home from a long trip I got caught in a deluge of rain that lasted at least 4 hours. I had to brake hard a few times (under the conditions). In the next day I already noticed that the brake 'grind' had all but disappeared.
I suddenly bought into the idea that perhaps the brake pads did in fact fuse onto the rotors and that the severe rain conditions contributed directly to cleaning the residue from the pads and resolution of the issue.
Sounds hard to believe I know, but my brakes are working perfectly again.
Bottom line: I was quite surprised that the brakes, as good as they are touted to be on 911s, did not stand up to the test on my outing at the track. I am scheduled to run again July 28th at Lime Rock so will report any new issues if they happen.

chuckbdc

Compared to street pads, brake pad compounds made for track use are desigend to perform better at high temps and hold up better with repeated hard use. They are not "stock" because they usually require slighlty more warm up, may be noisy, and wear rotors faster than normal use pads for the street use.

If you are going to run multiple events a season, you should look at pads and rotors as consumables, just like oil, brake fluid and fuel. That is totally normal, and should not be taken as a "issue".

Most DE participants have a fine time driving totally within the enormous capacity of Porsche stock street pads and never encounter the conditions you did. If you go to slicks and optimize the suspension, you may find other conditions created for a Carrera or Carrera S. The solution is some mods, or moving to a GT3 - which already has the essential ones.

fbroen

Sorry, OT -- Chuck, you weren't in and east of DC today early afternoon were you? Paced this one for a while:

chuckbdc

No not me. I took the "chance of thunderstorms" car to the office and am stuck behind the desk despite clear skys (hence the peeks to the forum for P-fix, sigh).

Besides, the spoiler says that fellow must have exceeded the speed limit somewhere. Would I do that?

fbroen

Ha! I am sure my spoiler was down?

livaz

she seems so small on your US roads, why do we have road build for smarts in here