Cooling down lap(s) - reasons ?

[graeme4130]

Hi All
Recently, I got into a discussion were some people were adamant that a cooling down period was beneficial for the life of various parts of the car (more specifically, carbon brake discs)
My understanding from a basic level of automative engineering is that a cooling down lap is mainly aimed at, and very important, for parts which are cooled by oil or water, and therefore give these parts (mainly engine parts and bearings etc) a chance for the cooling process to continue and for parts which get extremely hot (i.e. turbo's etc) not to have oiled cooked into them where it didn't get the required flow to bring them temps down
With ceramic, or otherwise, brake discs, then as they're cooled by ambient air temps, that a 'cooling down' lap would otherwise just extend the 'cooling period' as they're still receiving friction, and therefore just staying hotter for longer with no real benefits ?

I'd be interested to hear peoples thoughts on what the actual physics are for these parts to require anything other than just being parked up and left to cool naturally, rather than having another, admittedly slower, lap to just maintain those high temps a bit longer

Thanks in advance for you help

[graeme4130]

ViperDave said:

well on a cooling down lap you shouldn't be stomping on your brakes as hard as you can from 150mph, so the energy put into them will be far far less than the previous lap/s. In addition the increased air flow of a moving car, air drawn thought disk ventilation vanes and brake cooling ducts will cool them rather more quickly than sitting on a pool of stagnant hot air in the pits (unless its a very windy day) with the pads covering 20% of them preventing an even cooling and dumping heat into the caliper and fluid.

its quite possible that on a cool down lap you could get the disks pretty cool and no worse than a stop from the motorway exit

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But does cooling discs in this way add anything to the life of them ?