brake disc changes?

sno*jet · Jan 31, 2024

In '18 I thought cat lightened their brake disc for the mountain cat even more than the 17? watching a BDX vid a while back, the brake disc is solid on the Mountain Max. what were the alphas coming with? how about the catalyst?
Almost seems like cat sneaks old parts back in so they can re-use the marketing of the lightweight stuff again in the future. why would the catalyst not have the carbon TCL along with the lightest brake disc to date?

boondocker97 · Jan 31, 2024

The solid disks that started coming on the Ascenders are quite a bit thinner than the old proclimb "snopro" rotors with holes. If you look at the one on the blast he showed you can see it's thicker and the superlight rotor on that one is the old design that's also thicker. The superlight rotor in his hand is a completely different design to replace the thin mountain rotors.

The stock mountain ascenders started coming with a few holes, but went solid again later. The holes were pretty small and not doing a lot of lightening.

The most cost effective and lightest option is to take the stock Ascender or Catalyst rotor and have ZRP machine them for $100.

The Carbon TCL is thicker than the aluminum one on the Ascender and the aluminum allowed them to package things tighter on the Catalyst is my guess.

sno*jet · Jan 31, 2024

ok, good guess!
so the thinner disc came out in 18 or?
not sure id want to have it milled even thinner. I like the BDX on mine but I did spend a little time de-burring the holes. The blast sure could have been a lot lighter from the factory, what a shame

boondocker97 · Jan 31, 2024

Pulled out my disks tonight for comparison. The thinner disk with holes started in 2018 and has a different offset and caliper they ran with the aluminum driveshafts. Solid thin disks started coming in 2020 or 2021. When ZRP machines them the do more holes and cutouts and leave the thickness alone. I had to do some deburring on it when I got it back from them too.

ZRP must have changed the pattern and added more slots in recent years from what I can tell with the pictures and info they have on their website. It's a little wonky. My weight on the drilled 2018 rotor checks out so I trust the 1.56lb I also got with my scale.