hlee1169

So my brake pads are worn down to less than 1/4 inch after 11 track days, and the brake rotors are down to the minimum thickness. I am not surprised since I know DE will wear out these consumables faster, but I wonder if anyone else doing DE manage a longer life on the pads and rotors?

John's 991

My brake pads lasted less long - only 5 track days or so, but Laguna Seca is particularly hard on brakes. I replaced the fluid with Castrol at the same time as the pads and that really helped with fade. I will prob replace the rotors with the next set of pads and add stainless steel brake lines at the same time.

So interestingly I seem to be getting better rotor life with the stock pads but less good pad life, although the actual braking requirements at a DE changes considerably by track, driving style, etc.

chuckbdc

Out of curiousity- how does your 991 compare with other 911s you have driven at the track, with others that were in your run groups, in general, and if you have them, lap times?

John's 991

The other 991's at Laguna were in lower run groups, so don't think that is too applicable. The 996 and 997 911's I have driven were not mine, so I did not drive them more than 7-8 10ths. The 991 was more stable, turned in better and a lot roomier.

Good lap times for me at Laguna are 1:47-1:48 last time out on tires with about 15 heat cycles on them. Thunderhill was around 2:12 with 5-6 heat cycles (over the top)

hlee1169

John, I did about 6 track days at Thunderhill and 5 at Laguna Seca. Your lap time at Laguna Seca is similar to mine, my best is about 1:48, and my best at Thunderhill is about 2:16. My tires have more than 50 heat cycles, so they are getting quite hard though.

I have chased a few Cayman and 997.1/997.2 S at Laguna Seca, and Cayman was fast at turns, I can catch only on straight. I was on even pace with a 997.1 who knows the track well.

John's 991

I hope you are not the unfortunate fellow who tagged the wall in his orange GT3 at Laguna.

Salj

I just ordered new front/rear pads for my 991S with PASM. I have had 8 track days, mainly at Sebring. Rotors look like yours--hoping to get another set of pads out of them.

Alan Smithee

Seems premature for a relatively light car with relatively huge brakes. Perhaps PTV at work? The system uses brake pressure as well as torque distribution...

simsgw

I've never read the engineering doc's, so I can't assert it, but I have the strong impression that PTV is implemented with the S's electrically controlled equivalent of a limited-slip-differential. Differential braking is possible, but -- again just a strong impression -- I believe it is limited to PSM recovery measures, like the steering pulse applied when laterally-differential loss of traction occurs.

In any case, vectored torque would be applied to the rear wheels, not the fronts.

Gary

o2bcdn

I have 4 track days, about 440 track miles and about 3600 street miles on my 991S and pads appear to have about 50-60% remaining. A PCA instructor at one of the events who races a Cayman told me I could expect about 3 seasons out of my rotors if I did 4-5 track days per season. My track days have been at Road America and Autobahn Country Club near Chicago.

chuckbdc

I believe that it apples braking force to the inside real wheel under high speed decelerations and steering angles to sharpen turn-in. Some here have reported rear brake pad wear after serious pushing in DE driving. The amount of wear would be of course highly correlated to how the car is driven.

John 996 TT Cab

Just be glad you're not changing PCCB rotors with that cost. Page 79 of the 991 Brochure indicates that the PCCB's should be checked after every track event.

TSpyder

I just found out that a campaign has started to replace 991 pads due to complaints of excessive squealing. Perhaps you can have your pads replaced under this campaign. OTOH, the tech might look askance at the paper thin rotors

Spyder

John's 991

Interesting, my pads never squealed once, very hot, cold or in between.

simsgw

That makes sense Chuck. Turn-in under braking isn't as big an issue because the front tires are well loaded, but ir would help dynamically. I really wouldn't expect increased wear if the car was being driven well because the rears will be as close to threshold as the fronts and the technique will be to reduce hydraulic force to the outside wheel, not conversely.

And if we're not braking, just in overrun or accelerating, then the ELSD can provide the extra turning torque just as an LSD always does, but with controlled intent.

Of course, "highly correlated to how the car is driven" is always the gnarly boogey man in the closet. If we're comparing to brake wear when the car is not being driven well, then bringing the rears up to carrying their fair share of the work certainly will increase their wear rate.

Gary