Race Pads: Rotor Wear?

I have only a single data point, but the ST-43 pads on our saab seem rotor friendly. Same set of rotors on the car now as when we put them on 6 events ago. Still plenty of life. We'll replace the rotors anyway with the pads since they have some build up and vibration at this point, but it will be for that reason, not that they're worn through.

I've definitely heard others say their pads eat rotors, but I have no personal data to back that up.

We use porterfield front pads and the best semi-metallics Rockauto has to offer under $20 on the rear of our 1900lb mazda MX-3. We can easily get 2 races out of the front pads, one race out of the rear, and replace rotors every time we replace pads. $12 each for front rotors, $8 each for rear.

Edit:
Specifically on rotor wear, we could probably run 2 or 3 sets of pads on one set of rear rotors, but the fronts rotors are cooked with every set of pads.

I think it has a lot to do with your operating temperature range.  This is influenced by the car weight, car balance, and by the track.  I think Sonoma is really hard on brakes because you have to break from the high 80s into 2nd gear speeds three times every lap, (every 2:20 for us).

For many races we had lots of trouble with pad wear.  We were burning through the 98% of the Porterfield pads in one race at Sonoma.  We changed our front brakes to those from an acura CL for 1 extra inch in diameter and changed to the Hawk DT60s I think.  These lasted just less than a whole Sonoma race (it's bad to run out of pad material on Sunday afternoon while trying to outbrake another car into the bus stop, but those tire barriers are a fun slalom. 
The hawks were also super hard on our rotors.  Part of it was not the pad's fault though.  We had too much forward brake bias and the fronts were doing all the work.  So we got matching CL brakes for the back and changed to the ST43s.  We'll be starting our third race on our first ST43s in a month and the rotor wear is quite minimal (like less than 0.5mm).  I expect we might get 2 more races out of both the pads and the rotors!  I believe that these work for us because we have operating temperatures that were at the high end of the useable range for the Porterfields and the Hawks.  The ST43s have also never been scary when cold, they bite sufficiently when cold and warm up fast.  The only thing I don't like about them is that they are not easy to modulate with our power brakes.  The porterfields were much better at that.

Brakes don't need to be a significant wear item.  When working well, some of the pad material is transferred onto the rotor face and the friction is generated without removing material.  I think the worst pad wear is when you are operating above the pad's temperature range because the pad material burns off.  I think the worst rotor wear is when you are operating below the pad's temperature range when the friction is developed by the abrasive pads removing rotor material.  The ST43 compound is known for having a very wide operating temperature range.  Just call the folks at Porterfield they can put the compound on the right blanks for you and they are the nicest folks.  The compound is expensive to buy but cheap to use.

The one thing I take from these brake discussions is that unless Car A & Car B are the same make/model/relative speed, you really can't compare pad/rotor experiences.  Everything is sorta anecdotal rather than empirical. 

My anecdotal experience is that EBC yellows quickly consume both the pads and rotors on a heavy/fast car.  I very much like ST-43's for pad/rotor wear on big heavy cars and Hawk Blue for lighter cars.  At some point I will be trying ST-43 on the lighter cars too.  My mother says I can't talk about Carbotech anymore.

Hawk Blue and Black are both hard on rotors.  Particularly when cold.  Like on the street cold.  Even rolling around the paddock Blues will tear iron off the rotors.  You could see it in the surface finish.  It looked like the rotor was galling.  I never really loved the pedal feel with Hawks either.

PFC 97s and ST43s are both pretty reasonable on the rotors.  We'd get heat-checking long before wear became noticeable.  As mentioned, the ST43 temperature range is wide and forgiving, though a heavy and fast car with marginal rotor sizes may need to bump up to ST47.

Either pads wear or rotors wear.  If pads are lasting then rotors are wearing.  Pads are damn expensive.   Rotors are cheap.  Get where I am going with this?

Don’t want to say things are completely different, but what you’re seeing in the Dustbuster is NOT what we’re seeing in the LemonAid E30 with ST43’s.   We moved to those pads because of these type of reports, and let’s just say they don’t wear that way for everyone.  Not to mention their initial bite and stopping power isn’t great.

So... this is a perfect time to mention that how fast the car is, how heavy the car is, how drivers use the brakes, etc all can factor into this discussion also.

So front race pads  are often on average (depending on brand) $170 set.   E30 rotors are about half that. 

Absolutely!  We are stopping a lot more weight but from much lower speeds.  Our brakes are also massively oversized for those speeds but we still manange to keep enough heat in the rotors to keep the ST43's linear after about three laps (not in the wet).  We guesstimate our as-raced weight without driver at about 3100-3200#'s with 10.5" rear rotors and front rotors are 12.8".  When your top speed on the back straight of Gingermean is 90 mph on a good day, that is a lot of whoa for not much much speed.

We have used the Porterfield R-4Es on both our RX-7 and 914; both with great results in terms of both wear (pads and rotors) and performance.  Granted, the 914 isn't exactly known for staying on track long enough to really stress the pads, but in the short bouts of raciness it has seen, they have been great.  Brake ducting probably helps quite a bit, too.

Perennial Losers
Mazda 787b aka '75 914 - Org Choice @ The Ridge, 2015; IGS @ TH, 2018
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We had major brake pad issues this weekend.  ST43s up front and Carbotech XP10’s lasted Saturday but R4E’s on the rear at the end of the day on sunday.  Put a fresh set of R4E’s on the back with 75 mins left and burnt through the rears in that time as we tried to chase down the TaTa’s.

Time for a complete overhaul of braking system...

Agree with the rotor friendliness of ST-43 pads.  I kept data on the rotors and these pads from race to race.  Each race took .005" of metal off the rotors.  They still had a long way to go before their discard thickness, but they started developing cracks.   It wasn't wear that killed these rotors, it was overheating that killed these rotors

My bad.  I stopped using air ducts to cool them after getting wheels with much bigger openings. Braking behavior improved after the wheel change, (it stopped jerking right or left under braking at that point,) and I thought, "Ducts! Who needs 'em?"  Wrong.

Powerful brakes need powerful cooling to preserve the life of all parts in the vicinity.

We just pulled the rotors off the saab after 5.5 races with ST-43s and 0.5 races with autozone specials. There are some minor waves in the rotor surface, but i swear they are barely worn down. Going to get them turned and keep them around for spares just in case. They were centric blanks. We replaced them with the same. We are full ST-43 fanboys at this point.