Factory rotor min thickness or Girodisc thickness spec? I'm not sure they would be the same (?). What car, rotor size? What are the measurements, new and current worn condition?

I have also heard Hawks are hard on rotors but not sure they would be significantly harder than other equivalent race pads. For reference I've used DTC70's for a lot of years on the track, but my rotors have always heat/stress cracked to the point of needing replacement, I've never been concerned about thickness.

 

The full thickness range is only 2mm from max to minimum so if you really had 0.9mm you'd have almost half the life left. That said, when I'm at my minimum spec on these rotors, the grooves just about disappear, so I suspect they're 2mm grooves. The fact that your grooves are smooth in some areas and not in others suggests you have uneven wear. I'd speculate that if you had calipers that could measure the discs at the place where the groove disappears, you'd be at the minimum.

 

Jim, the coefficient of friction on DTC60s at 500F is about 0.7. At the same temperature, my PFC08s have a coefficient of 0.45. So about 50% more friction with the DTC60s. That gives me some indication of just how much more aggressive those pads are on rotors.

 

Yep, you are correct, 0.9mm left on the outside, and closer to the hat is probably at the minimum already, but that is hard to measure
so I have a dilemma, either buy another set of pads (not dtc60 but smth softer like ds2500) and presume that it won't go too far below the minimum on the inside.
or just replace the rotor rings and then go for new softer pads, which is correct but a more expensive option :-)

 

Your car, so your call. Personally, I'd bite the bullet and make the change of rotors and pads. I wouldn't run unevenly worn rotors at their minimum spec. I also wouldn't want to trash another nice set of rotors. So that means new rotors and new pads. There are a lot of pad options between DS2500 and DTC60. Those are two extremes of the spectrum. In the middle of that spectrum are pads like PFC 08 and 11, Ferodo 1.11 and 3.12, and several options from Pagid. I've had great luck with PFC08s, but I haven't really explored all the options.

 

This is 100% the cause. A more aggressive track pad will eat through rotors on the street. The Hawk DTC60 are definitely harder on a rotor when cold than the 1.11s. I've heard of people that keep a set of DTC70 around for if they ever get pad deposits on their rotors that caused shudder, simply running them for a week on the street to resolve the issue.

 

I have run Pagid yellows for over a decade on the track and street with brembo rotors from a BGT floating hat big brake kit. No problems. In fact I prefer this set up for the street because it's dependable with stopping power. No crap on the rotors, wear is always even, no need to change them after the track day, no having to bed anything in. Yeah, you get alot of brake dust, but I don't really care. All I have to do is wash the car and it goes away.

Bottom line: pad and discs are wear items. Find the best ones for your car that give you the best stopping power and characteristics you can live with and then replace them when they need to be replaced.

 

Holy thread bump!

Those appear pretty "groved" out. I have had customer's run the discs until you can't see the slots (like yours are starting to show).

As long as there are no cracks all the way to the edge of the rotor (outside or inside) you could still run them, but with those grooves I'd expect you might be experiencing some oddities.

--Aaron (also totalbrakes.com).

 

Your Ferodo prices are pretty good... on both your sites(companies?). What's the equivalent EBC to the DS1.11?

 

Well, Rennpart is my Porsche shop and parts website, Totalbrakes is my online brake store. I found it hard to sell the consumable hungry Camaro/Corvette brake pads under a "German" name. Total brakes seemed fitting.

It is very hard to compare pads between companies.

A EBC RPX or SR-11 would be on about the same plane as the DS1.11. Again, hard to compare pads between companies because there is no standardized test for their friction charts- you might as well draw squiggly lines yourself.

--Aaron

 

I don't see a post from the OP this year, so not sure what additional life he did get out of his rotors this season. I was warned at a tech inspection after 20 track days that my front GiroDisc rotors (350mm x 34mm) were cracking too close to the perimeter. One guy insisted I get new ones before the end of the weekend, which was kind of impossible. Others said don't worry too much - just keep an eye on them. I did just that for 7 more track days (24 sessions) which allowed me to finish out the year. I did not see any significant advancement of the cracks into or through the perimeter. To be safe, I did get new rotors and mounted them on the hats over the winter to be ready for the season. But I am not sure I couldn't have safely eked out a few more track days by keeping a very close eye on them (total inspection after every session). I only dropped about 1-1/4mm in thickness so that wasn't a concern. Grooves still pretty prominent. The photo below is the worst area I can find on these front rotors after 27 track days / 91 sessions. Outer surfaces seem worse than inner.



I think a replacement decision also depends on the level of driving you are doing. The more advanced or aggressive driver may wish to be more conservative. I am PCA White in a 2005 997.1S. Not a slouch on my brakes.

I do like these rotors despite their cost because they last a good while and they do save some weight over OEM iron (although I had Ceramic rotors so I actually gained weight).

 

Those r not cracks, its what i would call crazing. They r only on the surface of the rotor and r normal for the girodisc. I would run them to the minimum spec before getting new.

 

Here is what it looks like on a Brembo 355x32 with 25+ track days and a couple of sets of Pagid Yellow 29s. I know the hats look like he'll after 15+ years but still functional.

New rotors and hats are going on shortly and the brake dust will be scrubbed off the track wheels as well.