[Lwerewolf]

I wonder how strong the driveshafts would have to be to handle all the braking torque transmitted through them. Dissipating the heat would also be an interesting problem. Also reduced clearance and/or increased drivetrain complexity and a million other things.

There are good reasons why people haven't moved away from old school rotors, pads & calipers right at the wheel hub, for basically any application.

[Lanolderen]

My guess is torque isn't as big of an issue since on acceleration you break traction before anything snaps. The big issue in my mind is technically cooling and practically packaging since you already have the space inside the wheels.

I know inboards are used on some formula student cars in the rear (on some karts as well?) but I haven't looked up the issues they have with them.

[Lwerewolf]

Brake torque is far higher than engine torque and can be applied at speeds where tire traction is far greater - at least at the front. The rear makes far more sense for this application - assuming a performance RWD or AWD vehicle, the rear driveshafts already handle most of the acceleration load, and max rear braking load is practically severely limited by the load transfer to the front.

Formula student cars and other open-wheelers have far greater packaging flexibility as well. A quick search doesn't bring up a whole lot of encouraging discussions on FSAE and related places re: inboard brakes, please share if you've seen such.