Ascent Rotors, total mass and overall cooling

So I’ve read a good amount on the Ascent front rotor issues and confirmed by speaking with a good friend of mine who’s a Subaru Master Mechanic.

General consensus says the Ascent front brakes are beefy. The rotors are well sized (diameter) and the calipers are an upgrade for pretty much all other Subarus.

However, speaking with friend above, he’s noticed some interesting peculiarities with the OEM Ascent rotors:

1) in his opinion (he hasn’t actually weighed them), for the size of the rotor they feel much lighter/less dense than similarly sized rotors or even smaller ones given surface area to mass. Keep in mind, he sees many more brands than just Subaru coming through this shop. He has felt a LOT of rotors.

2) when he attempts to turn Ascent front rotors, and ONLY Ascent front rotors, he has to do things that he never needs to do for any other rotor. He has to use 2 dampers, one inside, one outside and he has to adjust the lathe to remove just about thee smallest amount possible without the rotor vibrating so bad he has to stop the lathe (even with the dampers). For him, turning front rotors for an Ascent turns into an hour + ordeal because he has to machine then so slowly over many passes, where most rotors, its one and done.

So he’s to the point when he gets an Ascent for a front brake job, especially when warranty work comes into question, he doesn’t bother turning them at all, he immediately gets new rotors.

Add in my experience one day recently when I went to wash the Ascent. I had driven her for some errands. Parked her, went inside to change and ended up coming back out about an hour later… I always spray the car down top to bottom pretty thoroughly before I add soap… when i got to the front wheels and sprayed… the water instantly vaporized. The brakes/rotors an hour later were still STUPID hot.

Maybe this has already been discovered, but I think a combination or poor cooling, and low mass rotors (coupled with the Ascents sheer bulk) end up creating a condition of extreme heat (even in braking terms) leading to warped rotors/pad deposits which as we know cause the brake shuddering.

For those who have switched to aftermarket rotors/pads… does the issue re-occur? Any other thoughts or experiences?

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