Parking brake question

[944Spec_bound]

They say at the track to not use your parking brake after hot laps. Makes sense if your discs are the parking brake, but isn't that the reason for the parking drum on these cars?
Everyone still says not to use it, are they just ill informed?

[jpk]

No, they're correct. It's a different issue, but a problem just the same.
With disk brakes, clamping the pads to the hot rotors traps heat under the pads, causing the rotor to cool unevenly. This can cause the rotor to warp.
With drum brakes, what happens is the as the rotor/drum cools, it will shrink slightly. This will constrict the inside diameter of the drum part of the rotor. We're only talking about a small fraction of a percent change in size (0.00116%/degree C for iron, but were talking about potentially 400+ degC temps) , but that can be enough that you will either clamp down on the shoes so hard that you can't release the brake, or even possibly fracture the drum part of the rotor.

[944Spec_bound]

since you put it that way, it makes sense. I'll keep a couple of blocks handy.
thanks.

[Cking1975]

Yes, plus you do not want to wreck the brake shoes as they are 200 USD to replace. another thing I always did was open the hood after hot lapping, they put all the insulation in the engine to keep it quiet, but that traps heat.