Nice find!Just FYI - While doing pre-season maintenance, I noticed a few drops of what turned out to be brake fluid right below the caliper housing/brake pad area. Thought it would most likely be just a seal ring (square o-ring) problem. Pulled the outer side of the housing off, removed piston, and cleaned everything up. To my surprise, there were 2 small cracks running from inside the seal ring through the groove to the outside creating a path for brake fluid to leak out. I did same on the inner side, and again, to my surprise, there was also a small crack similar to outside. Looks like heat stress/heat cracks.
IMO, the brakes are none too big on these sleds in the first place. Then, add track with lots of long studs that don't allow track to lock very easy, and you have added lots of load to the brake. Probably adds allot more heat to the rotor, pads, pistons, fluid, housings. I guess after many many heat cycles, aluminum cracked.
Maybe I shouldn't use brakes so much LOL? . Slowing one of these rockets down from over 100 MPH all the time I guess takes it's toll.
Sled is 2017 Cat ZR9000 Ltd Stage 4 with only about 7,000 miles. Tuned since day 1. (240 ea. 1.575 Megabites mounted on double & single ProLite backers).