What's going on with these rotors
 

Gents,

The rotors pictured had one two-day event on them with the new Wilwood BP-28 compound on my TSE 11.75 BBK. They looked fine afterwards. I had four consecutive track days at VIR coming up, and I purchased a new set of DTC-60s. I didn't believe the Wilwood pads would last even another full day. I don't like the -60s, even though I have my best VIR lap time on them, but I haven't been able to get Raybestos ST-42s (or any other Raybestos pad) for the 7812 backing plate for probably a year. While not as fast as the -60s, the ST-42s are incredibly rotor friendly and last forever--perfect for HPDE. The DTC-60s create the ring pictured around the rotor.


https://cimg5.ibsrv.net/gimg/www.mia...9e9208e7ce.jpg

I took a sanding block to the rotor at the bottom to get a better look. The rotor at the top is unsanded, but you can still see the ring. What is going on?
The cracks look worse in the pic than they do in real life, and none will catch my fingernail, but it does seem like these rotors should be relegated to spares status until replaced.

Here's a pic of a couple of the DTC-60s after about 11 hours of track time.

https://cimg7.ibsrv.net/gimg/www.mia...ea8ea9b3ba.jpg

Thanks, and Happy Thanksgiving to All of You and Your Families,

Gents,

The 2024 HPDE season is starting for me soon. I'd really like someone to weigh in on what might be going on with these rotors, and if they should be scrapped.

Thanks,

When rotors are new they are soft. After use the surface hardens and to some degree the areas that reach a higher temp will be harder. The cooling rate is a factor as well. Sometimes you will have areas that harden at different rates and will look different. Some will also have different amounts of pad deposition. The surface cracks are from the surface expanding and contracting a higher rate than the base/surrounding material. This can be caused by the location of the mass, internal fin geometry etc. I would probably keep using them if the function is acceptable and just keep an eye on them. In performance driving/racing rotors are much more of a wearable item. I prefer to use products that are readily available and more in budget.

I'm not one of the experts here, but I'd be fine continuing to use those rotors. I've been racing on DTC-60s for a few years now and sometimes the rotors look somewhat similar to yours, ie "heat checked" and a bit odd wear. The odd wear usually fixes itself after more time or new pads. Just keep an eye on them and run it, IMO.

I don't know you'll get another day or not from the pads, hard to tell from the pics. I tend to swap pads a bit early and throw them in a box I bring with me to the track. That way I have emergency spares and if I have too many, I'll opportunistically throw them back in and use them up. Switching to PFC 11s myself after years of DTC60 use, looking for more modulation. It remains seen whether I can be as blasé with the PFCs as I am with the Hawks.

Could be residual pad material that the DTC60's didn't scrape off. Usually the dtc60's are harsh enough to remove whatever's on your rotor. I used them to "clean" some improper bedding of my street bp10 pads and they worked great, but the dust is crazy. Personally I'd get the rotors turned if they're thick enough for peace of mind

For the cracks, if you don't feel safe, just replace it