Rim brakes

[markocosic]

What's the mass of a 'typical' 6" width 10" dia alloy rim? The mass of a 'typical' rear brake disc/rotor?

How hot does said rotor run and how hot could one sensibly run a rim? ie; anybody already answered the "would using a rim as a brake be stupid/impractical" question?

[markocosic]

What's the mass of a 'typical' 6" width 10" dia alloy rim? The mass of a 'typical' rear brake disc/rotor?

How hot does said rotor run and how hot could one sensibly run a rim? ie; anybody already answered the "would using a rim as a brake be stupid/impractical" question?

[Igor]

I've seen a couple of rim-mounted discs over the years at the Formula Student competition. It is hell to change a wheel and the gains are only minor for the extra effort. I don't think any of the teams ran them for a second year.

Using the rim itself as a brake would seriously mess with your tire pressures.

Igor

[Agent4573]

There was athread on here a few weeks ago with a plot about the strength of aluminum as it got heated. None of the aluminum had any strength left in it above 200-250 degrees C i believe, and I hope most people run thier brakes hotter than that. I know we run hot enough to just about melt aluminum, so using an aluminum rim as a brake rotor would be kinda sketchy unless you took some serious precautions.

[MikeWaggoner at UW]

Western Washington University used to run inside out brakes. The rotor mounted directly to the rim, through radially mounted machine screws.

The weight savings were kinda small, since the rotors had to be big enough to fill the rims, and thick enough to be able to fit machine screws. We used sliding calipers instead of a matched-pot design (bad), so wheel removal wasn't that big a deal.

I think with an aluminum insert that mounted to the rim, and rotors, a good system could be designed.

You should be able to find pictures at http://dot.etec.wwu.edu/fsae