ejblanchard

I did the HPDE Father's day event at Barber MSP in my 2014 Carrera S. We did 8 sessions of 25 min each with a cool down lap at the end. The car has 5300 miles on it. After the weekend, my brakes were making a low grinding noise that was not there prior to the weekend. The dealer says the REAR pads are worn and the REAR rotors may also need replacement as they have turned a blue color, indicating that they were very hot. This is the first track session for the car.

I have three questions:

1. Is it unusual to wear the rears down first?
2. Is it unusual to wear the rotors in one hpde weekend and if so, what can I do to prevent it?
3. I want to go back with OEM rotors and pads but would like feedback on other options that have performed for longer if available. Are there better options?

I want to keep doing HPDE events and have pretty good financial resources, but want to limit my expense as much as possible.

Thoughts or helpful tips are appreciated.

Team Plutonium

Yeah, going through a set of pads is normal... the rotors should last a lot longer though.

LexVan

Torque Vectoring uses up the brakes too to rotate the car in turns.

John's 991

Yes, it is normal to wear out the rear pads more quickly than the fronts, especially with traction control on. But even with it off, the PVT increases the wear of the rear pads.

My first piece of advice for you is that if you are going to do DE's then you are going to have to consider pads, rotors and tires as consumables and you will go through a lot of them. Its not a big deal, however, just a little $$. My second thought is that you should consider learning how to change pads and rotors yourself. It is quite easy and there are DIY's around to help you. It will save you a lot of $$ and help you better understand what is actually going on when you brake.

Regarding the rotors, you should not need to replace them just because they got hot. You should see little cracks radiating from the cross drill holes, but as long as the cracks don't connect two holes together, and they are not warped or deeply grooved, they should be fine. The dealer is probably being over cautious. If it where me, I would wear them all the way out.

I have numerous track days on my car, and have gone through about 5 sets of brake pads and only one set of rotors. I am also about halfway through my 4th set of tires. I switched to Pagid R29 brake pads as they perform better on track and last about 2-3 times longer than the OEM pads, but they can make a lot of noise if not bedded in when driven on the street. There are lots of discussions about this if you do some searching.

Larry Cable

I was very afraid that this would be the case ... does disabling PSM also disable PTV+?

drcollie

Good advice here...may I add:

If you are going to continue to do DE days and a fair amount of them, get a set of dedicated track rotors and pads that you put on the car the night before the event. You can run a much more aggressive pad that way and when you are back home, swap the street set of rotors and pads back on the car. Pads and rotors are definitely consumables and work better mated together (track pad to track rotor, street pad to street rotors) due to the material buildup on the rotors that doesn't place nice with the material from the OTHER pad if you only run one set of rotors. When you get good at doing it, then its less than an hour do to all four corners. Also run a dedicated set of track tires and wheels, swap them all in as part of your pre-track day prep.

A proper set of track pads with more bite increase your stopping power considerably if you have sticky tires on the car. Don't forget to change out your brake fluid 2x a year if doing heavy track days. All in the cost of playing at speed....

Larry Cable

Note that there are factory workshop guidelines wrt rotor wear and replacement that the dealer should use; these comprise:

1) a minimum rotor thickness limit

2) "crack" length limit (length of cracks from drill holes permitted)

unless those are exceeded the dealer should not recommend replacement.

Since it appears that PTV+ is always on (that's a shame - I wonder if there is a fuse that can be pulled or a PIWIS option to disable) the only remedy is to ensure that you perform a proper cool down lap at the end of each session (this will not reduce pad or rotor wear that is a function of PTV application) but
it will allow the rotors to cool properly and should reduce the rate of cracking.

This is a well known "issue" that 1st raised its ugly head with the 997.1 GT3 brakes, where Porsche adjusted the (initial) rear brake bias and failed to cool the rear rotors properly, (then) ADB was
problematic in applying the rear brakes thus increasing temps and wear...

You might consider going to a harder (track/street) pad, this will reduce pad wear but may result in more rotor wear, and they might also squeal like a bus/18 wheeler on the street until they get up to temp

Larry Cable

for a higher temp fluid like SRF or RBF with high dry/wet boiling points ... slotted vs "drilled" aftermarket rotors probably also will improve rotor lifetime

John's 991

Hi Larry, I don't believe PTV can be disabled. It works well and is pretty unobtrusive, so other than increasing the rear brake pad wear, there is not much downside to it. On the other hand, while the PSM is light handed in Sports Plus, I still find the car slightly more "controllable" when it is off.

As an example, Turn 7 at Sonoma a mid-turn lift with it off will allow the car to rotate and point it nicely into the esses. With it on, the car won't rotate much. Of course the downside is that you are playing without much of a net, although it will intervene if it senses you are really getting out of shape, even when off.

Regarding the original post, good point drcollie on brake fluid. If you are going to do DE's then you want higher temp brake fluid. I use Castrol SRF, but Motul and others also work well. Personally, I bleed the brakes between track days as a matter of course. This topic has been discussed at length as well, but I like to get the car in the air and the wheels off and take a look around anyway. At that point, its 5 minutes a caliper to bleed them. I also got a brake pad measuring tool, which allows me to track pad wear accurately.

Larry Cable

Thanks for the insight, I dont plan on tracking my 991 (when I get it, with the exception of the obligatory Euro Delivery laps of the Nordschleife) as that's what
my "real" GT3 is for (the 991 GT3 guys wont like that!) ...

The PSM on the GT3s has much higher limits and is rarely (never) detectable intervening on the track ... I'd certainly be running in Sport+ and perhaps even
with PSM off on a dry track, but as you point out, its nice to have nannies
there just in case, which of course they are in emergencies ...

totally agree with better fluids, and perhaps a harder pad ... shame about PTV+ though ...

John's 991

The word is that a stock 991 CS2 is just about as fast as a stock 997 GT3, although I doubt it has the same level of feel. You are also missing out on the popular BBQ feature of early 991 GT3's.

In any case, your car looks great and I would never sell it either.

Larry Cable

fire ext is a MUST have option

ejblanchard

Good information from all. thanks.

johnhv

For what its worth did the Master's program at Barber MSP in April. For 2 days spent a lot of time on the track in a 911s. I did not experience any brake fade and was told by the instructors they use stock pads and fluids. I have been doing DE for the past 10 years and use brakes a lot less now then when I started.

j080808

Have had the rears shot twice at the same track on 2 different occasions. Another forum member (instructor) had the same happen on our last outing.

Dealer replaced the pads and rotors (warranty) but I doubt they will do it a second time. Would be interesting to see if the low humming/grumbling goes away with just pads, I believe the rotors are warped.

I dont have PTV, so I believe traction control is the culprit.