Any here have experience with StopTech carbon brake rotors? I’m thinking about getting them combined with the Porterfield pads.

 

I didn't realize they made any carbon rotors. I don't see them on their website either. Link?

 

https://www.buybrakes.com/product/17...model=selected

I was told there’s also drilled & slotted high carbon brakes too but can’t seem to find a link or pictures.

 

Those are not carbon!

Those are big heavy 1PC dustbin lids.

 

They are carbon. I think you might be confusing “high carbon” with “carbon ceramic.” Not the same thing.

 

Obviously, just marketing speak then, they will be no lighter than the regular stock 1PC items.

 

StopTech "High Carbon" are just regular cast iron/steel rotors with a supposedly higher content of carbon in the metal than regular ones. I am a fan of these rotors however and use them on my own cars, because they seem to wear much better in conjunction with performance pads (e.g. ceramics) and they have the black coating on the bells and internally which stops them from rusting and looking like crap.

For example the rotors on my XJR have done 47'000kms and are only half worn, same with the EBC Yellowstuff pads, they're about half-way gone.

Centric & StopTech have the same "high carbon" product with the black electro-coating, R1 Concepts used to do a version of them as well but seems that they don't have them anymore...

 

In general terms, high carbon steel is harder but more brittle. I would not recommend drilled rotors made out of such material.

 

I had those on my previous car in conjunction with ceramic pads and was quite happy with them. As has been pointed out, carbon is not the same as high-carbon cast iron. They were no lighter than stock but worked well, were quiet, and with the ceramic pads, generated very little (visible) dust.

 

Why? Rotors out of all things can stand to be brittle. There's very little shock force into a rotor, and the higher carbon would help with cracking.

 

I'll preface this with the note that my formal training in metallurgy was relatively short, and relatively forever ago, but it was at a fine university. Nevertheless, it was one of the most fascinating courses I took.

I think that "high carbon steel" is lower carbon than the point at which it starts being "cast iron." From memory:

Iron is less than 0.5% carbon and pretty much immune to hardening and annealing.
Steel is 0.5% to about 2%, and hardening and annealing are used to adjust hardness versus toughness. Generally harder is more brittle, so some hardness is traded for resistance to fracture.
Cast iron is >2%, and heat treating adjust the crystalline structure of both iron and included carbon to adjust the brittleness. I think silicon is part of this too, but memory fails at that point.

Adding other elements to create modern alloys allows some of the age-old wisdom to be thrown out the window. The StopTech site notes chromium and molybdenum in the "high-carbon" rotors.

When I was racing motorcycles, I had some lengthy conversations with the Brembo importer, and he noted that Brembo changed formulation from traditional cast iron to what they called "superbike steel" because they reached the limit of what the old cast iron could handle before cracking. I've seen rotors fly apart under heavy braking and the results were not desirable.

I'm sure someone will correct me on some points because this is the internet.

I will add that the current WorTec group buy was probably doomed until Lance (Unhingd) blessed the heat treating process used before drilling.

 

 

I'd have preferred slots only, but you kids like your bling.