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YOUR RESEARCHTrackday brake failure - help please
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Check when i did mine
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Leading evidence: 'Check when i did mine' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, the most frequently mentioned possible cause is '25mm might be better' (1 discussions; 0 report identifying it and 1 suggest it). The most frequently discussed action is 'Check when i did mine' (1 discussions). For that action, 0 discussions report a resolution and 0 report an unsuccessful attempt. No action has an explicit, attributable resolution report under the current rules. These are forum reports and suggestions, not a confirmed diagnosis.
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My disc holes had been cleaned/blasted clear prior to track day.
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i've fitted a 997 GT3 brake master cylinder to a 987.2 Cayman due to the soggy brake feel of the oem cayman
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I’ve fitted the gt3 one to my 996.2 great improvement.
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can happen as mentioned but since you had replaced the racing fluid recently, this is very odd
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911uk: 1 discussions
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Hi folks,
I should start by saying the car and I are fine. No crash. Sensationalist thread title aside, I did have a very odd brake issue yesterday at Llandow trackday.
Fresh racing fluid, pressure bled this week, braided lines, new discs, new Brembo sport hp2000 pads, gt cooling ducts front and rear
The brakes were brilliant, then about 10mins into my first session my pedal went to the floor, with no warning.
However, the pedal came back immediately and the brakes were great again, but the bite point was a bit lower for the rest of the day.
Never had anything like it. No vibrating, brake fade etc, good bite. Any ideas?
Damaged my confidence, but still managed 49s dry and 52sec wet laps. Great day, with nearly everyone complimenting the exhaust note!
love this car!!
Read this:
Brake failure at track! Optimal brake setup?
Hi all, So I just went to my second track day, all parameters same except, I pushed the car harder, had a passenger 100kg, braked later and at the last corner of lap 4 (Slovakiaring, 5.9km), I noticed extensive brake fade in the pedal (e.g. pressed 60% no reaction) but it braked sufficiently...
911uk.com
Thanks, I did see it. This thread recommends parts I already have fitted and doesn’t diagnose the actual pedal issue, and also has bad brake fade (which I didn’t). My disc holes had been cleaned/blasted clear prior to track day. What am I missing? Does this thread recommend new discs as the final solution? Cheers
So I have decided to do a full bleed, but whilst at it, replace the master cylinder as peace of mind (perhaps internal seals gone?) and to reduce the long pedal travel and high effort required to apply the brakes.
Lots of people are upgrading from the 23mm standard 996.2 cylinder, to the 997 GT3 at 27mm but may I ask if the 996 C4S/Turbo item at 25.5mm would be a better choice for standard brake setup? I’m concerned some have found the pedal travel too high with the 27mm item.
Also given I do not have PSM, I do not think I need any custom pipework? Cheers
i've fitted a 997 GT3 brake master cylinder to a 987.2 Cayman due to the soggy brake feel of the oem cayman
the master cylinder with a 27mm bore size, instead of the 25mm bore will fit the 996 but you will need a line adapter for the one exit port as BOTH ports on the gt3 are the larger 12mm instead of one 12mm and 1 10mm on the stock 25mm master. It also uses a pressure seal against the booster instead of the pring but that should fit fine. I've always used this larger master cylinder and it will improve pedal pressure with the larger brakes.
Note, I'm not a mechanic and just DIY so you'll have to check and confirm it all works and fits fine
this is what i checked when i did mine
Cayman & 997 and 996 (with standard brakes) – 997.355.910.00 – 23.8 mm bore
Cayman S & 997 S and 996 TT – 997.355.910.10 – 25.4 mm bore
997 GT3 - 997.355.910.30 and 996 TT with PCCB – 27.0 mm bore
Thanks for the reply. I assume yours is a cayman S? You went from 25 to 27mm? I had a 987.2 base cayman and always thought the brakes were great… better than the 996.2
987.2 S
brakes were very soft and not at all suitable for a track day especially trying to rotate into corners trail braking, the 997 GT3 BMC solved the feel issue
Do I need to be concerned about front/rear brake bias moving from 996 c2 BMC to 996 turbo BMC?… total front caliper piston area of 996 c2 does not match the turbo…
996 c2 single caliper piston area
Front = 45.4cm2
Rear = 26.5cm2
996 turbo single caliper piston area
Front = 50.8cm2 (12 percent increase at front)
Rear = 26.5cm2
Total area 7 percent increase
23.81 to 25.5mm BMC = 7 percent increase (matches above)
23.81 to 27mm BMC = 13 percent increase
I’m not sure what all this is telling me
I am going to go for a 25.5 BMC. Seems like I’m the only one!?
