Is it normal for rotors to wear as fast or faster than pads?

[kthacher]

I had my dealer check my brakes to make sure that I am set for another track day . He came back with the following data. If you look at this, I appear to be on track for the rotors being replaced at the roughly the same time as the pads, if current wear rates continue. This is after 22,000 km, and just three track days. Four coming up - can't wait. Does this look normal to you guys?

While I am at it, what do replacement pads and rotors cost?

Pads

Left front 7.61mm, right front 7.52mm (new 12mm, limit 4.6mm)

Left rear 9.73mm, right rear 9.81mmm (new 13.2mm, limit 3.8mm)


Rotors


Left front 33.1mm, right front 33.2mm (new 34mm, limit 32.4mm)

Left rear 31.1mm, right rear 31.1mm (new 32mm, limit 30.4mm)

[MotherTucker]

No, it's not normal to wear out the rotors before the pads. That's really hard to do unless you are using some ridiculously hard pads like old Porterfield race pads.

But looking at those numbers, I'm not at all sure that's the proper conclusion. A mm of steel rotor wears out a lot slower than a mm of pad material. I've been tracking my R8 hard for 2 years, and have never worn the rotors down. But I've had to replace the front set 3 times, always due to heat stress cracks that form starting at the holes in the rotor.

I'm still waiting for a cheaper set of non-drilled aftermarket replacement rotors (preferably slotted) to be made.

mt

[kthacher]

These are stock pads. This is how I got to my conclusion on wear rate, using left front as an example.

There is 12 - 4.6 = 7.4 mm of useful brakepad life.
I have used 12 - 7.6 = 4.4 mm of the pad

So I have consumed 4.4/7.4 = 59.4% of the pad

There is 34 - 32.4 = 1.6 mm of useful rotor life
I have used 34 - 33.1 = 0.9mm of the rotor

So I have consumed 0.9/1.6 = 56.25% of the rotor.

Running the same calc on the rears would show a relatively higher % of wear on the rotors. I had assumed in my thinking that this wear is a linear function and that the trend I have seen so far is going to continue.

[desperado]

...unless you are using some ridiculously hard pads like old Porterfield race pads...
mt

Hmmm. A while back I purchased a set of Porterfield R4 pads (which I haven't used yet due to longer than expected life from the Pagids). MT, based on your experience (or what you've heard) do you think the Porterfield pads will be much harder on rotors than the Pagid RS29 or the Carbotech XP10/XP12? So far, I've had excellent rotor life using the OEM pads on the street and switching to the RS29 for track days.

R-4 - Designed specifically for heavy duty motorsports, the R-4 brake pad was our first and is our original Carbon Kevlar brake pad. Being able to maintain an average of .50 friction level within a very wide temperature range gives the R-4 pad astounding versatility and makes it very suitable for a wide array of various track conditions. Another inherent characteristic of our Carbon Kevlar material is how quickly the pads warm up to race temperature which is quite helpful during restarts, and when track time is limited. Optimum R-4 operating temperatures are 450°F and above. When used with cast iron and steel alloy rotor, the R-4 compound requires minimal bed-in period.

R4-E - A Carbon Kevlar compound made to last a bit longer than the original R-4 compound. Porterfield’s R4-E pads have an average friction level of .460 and perform best at temperatures averaging over 600°F. The R4-E compound is designed to endure higher prolonged temperatures and still have pad life as long or longer than Porterfield R-4. This pad is great for club enduro events and applications where temperatures are at their maximum.

http://porterfield-brakes.com/images...6_02_43_53.pdf

[Europrice]

You aren't running race/track pads on the street are you? If you run aggressive pads meant to be used in track conditions on the street you will chew through rotors like a fat kid eating a snickers (no offense to hungry big kids). I ran Hawk black compound pads on an Audi of mine on the street out of laziness, since it was a secondary track type vehicle, and I ran through a set of rotors in what couldn't have been more than a thousand miles essentially. I would find metal flakes in the wheels that would be rusting versus finding brake dust.

If you are eating rotors it's usually a function of too aggressive a compound for your use, ie you aren't getting them up to the pads operating temp and keeping them there. If you are swapping pads back and forth maybe try a less aggressive pad on track.

Cheers,

[kthacher]

No, I run stock pads and have never run anything else.

[Maverick]

If you're interested in a nearly new set of rotors and stock pads let me know. I had a 'warpage' issue on a trip across Europe late June and had to refresh all 4 rotors and pads with stock issue ones. Since my car is supercharged I'm now upgrading to Alcon discs and Pagid pads and will be selling a 'nearly new' set of rotors and pads. Approx, 1,500 miles on them.

[MotherTucker]

Desperado -

I am indeed referring to Porterfield R-4 pads. But the ones I have are several years old, I don't know if Porterfield has changed the makeup of that compound. The R-4's I have are very tough on rotors. And if you run them at night, you can actually see sparks flying off the rotors when you brake hard! They are really cool to look at at night due to the sparks, but they don't grab real hard until they get up close to 600F, and until they get real hot, they chew the snot out of the rotors. They are full race pads only.

You should try them at night, and tell us what happens :-)

mt

[harrison]

It is safe to say...The pads that create the most dust are the most rotor freindly. \"/

[Europrice]

Good point Harrison. In most cases a dusty pad on street is going to be a softer pad, not all, but most.