991 GT3 brake issues
07-29-2015, 05:03 PM
#16
RL Community Team
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Have you ever done the arithmetic? For example, the Thunderhill NASA 25 hour enduro is typically won OVERALL with total race distance of under 2000 miles. The times I have done it in a wimpy MX-5 we had to do at least one pad change. It is unusual to drive on most any track at a speed of over about 80-90 mph average. 2500 track miles is well over 25 hours at speed.
I don't know about you, but I have never driven any car at speed on track for 25 hours without changing pads at least, and for heavier, higher power cars, multiple pad and rotor changes.
The OP did not indicate how much of the 750 miles was on track, but if it was somehow all track, I know I could have destroyed my brakes, as in backing plates hard against rotors and collateral damage of dust boots burned up and perhaps even pistons damaged by getting so far out of bore they **** and gall up.
Hence my query above.
And from my preliminary experience with my 991 GT3 I am not sure I could get through even a single weekend DE without some brake service and I would definitely bring spare pads and fluid just in case. I have some pretty noticeable brake wear from 2 30 min sessions.
I don't know about you, but I have never driven any car at speed on track for 25 hours without changing pads at least, and for heavier, higher power cars, multiple pad and rotor changes.
The OP did not indicate how much of the 750 miles was on track, but if it was somehow all track, I know I could have destroyed my brakes, as in backing plates hard against rotors and collateral damage of dust boots burned up and perhaps even pistons damaged by getting so far out of bore they **** and gall up.
Hence my query above.
And from my preliminary experience with my 991 GT3 I am not sure I could get through even a single weekend DE without some brake service and I would definitely bring spare pads and fluid just in case. I have some pretty noticeable brake wear from 2 30 min sessions.
But if all of the 750 miles were at the track, in a span of 3 months, then the OP has my admiration.
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07-29-2015, 05:08 PM
#17
Oh, I could easily do 750 miles on track in 90 days, but don't have the $$$$$ to do it in my GT3. I probably drive at speed about 5 hours a month or so on average, hence my vast experience with nuking brakes from laziness and deferred maintenance, not to mention other 100% destructive testing mayhem. Primary track duties fall to my trusty turdo Miata. Best track car evah!
07-29-2015, 05:14 PM
#19
RL Community Team
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Oh, I could easily do 750 miles on track in 90 days, but don't have the $$$$$ to do it in my GT3. I probably drive at speed about 5 hours a month or so on average, hence my vast experience with nuking brakes from laziness and deferred maintenance, not to mention other 100% destructive testing mayhem. Primary track duties fall to my trusty turdo Miata. Best track car evah!
My biggest problem is time. The lack of it.
07-29-2015, 05:40 PM
#20
Did you inspect the rotors for cracks before driving ? I've seen drilled rotors where you have a crack running to to the edge that cause the rotor to warp and on braking chews up a caliper. Calipers will also warp, but I would expect that to be after more like 10,000 miles of track abuse.
07-29-2015, 05:43 PM
#21
Can only speculate without more facts and photos. You said brakes were ok at 1750 mi, but how much wear on the pads/ rotors at that point?
For me a typical DE weekend (8 20-25min sessions) would be about 280 track miles and 120 road miles, 400 total. So 750 miles from the brakes being "ok" to being toast is maybe 2 DEs? I've only done 3 days so far in the GT3 but I'm sure for me I can get 2 weekends out of a set of stock pads. But I can also believe a really aggressive driver could use up pads in 2 weekends. Rotors should last longer but maybe badly cracked? Being told the calipers need replacing really sounds unusual.
Maybe the OP can give more info.
For me a typical DE weekend (8 20-25min sessions) would be about 280 track miles and 120 road miles, 400 total. So 750 miles from the brakes being "ok" to being toast is maybe 2 DEs? I've only done 3 days so far in the GT3 but I'm sure for me I can get 2 weekends out of a set of stock pads. But I can also believe a really aggressive driver could use up pads in 2 weekends. Rotors should last longer but maybe badly cracked? Being told the calipers need replacing really sounds unusual.
Maybe the OP can give more info.
07-29-2015, 08:06 PM
#22
Nordschleife Master
One possibility is that the ceramic pucks cracked (we've seen a few cases of this already). Supposedly the ceramic pucks are not available to order as a part or rebuild kit and you need to buy an entire NEW caliper to get them....
07-29-2015, 08:53 PM
#23
I would personally expect that to be a warranty item. I'd also hope a dealership would go to bat for me to get that covered under warranty
07-29-2015, 10:09 PM
#24
Burning Brakes
It would be fairly outrageous for a shop to recommend replacing an entire new caliper just because a puck was cracked. I recently rebuilt the calipers on my 6-3 and had to replace a couple pistons. Can't buy them over the parts counter, but Porsche Motorsports sells rebuild kits for the 6-3 Cup, which use identical parts to the street 6-3. Might be worth checking if this is also true for 991 Cups and street cars.
07-30-2015, 10:53 AM
#30
Rennlist Member
....lots of variables here. One big one that I forget is the brake requirements brought on by the stability management system. So the amount of usage per mile may be considerably more than traditional braking. I have heard some talk about short pad life in the new cars.
Last edited by Texas RS; 07-30-2015 at 11:38 AM.