Caliper placement

[Senninha]

Something Ive often meant to ask of those more knowledgeable than I is about caliper placement.

Does it make a difference to the performance of the braking system? Particularly on performance cars Ive seen them, front of disc at 3 o'clock, rear of disc at 9 o'clock, rear and low down at around 7 o'clock and front and high up at around 2 o'clock.

I was going to post a few examples until on Sunday at the SCC I noticed this in the Aston Martin display. Two seemingly identical Vanquish models yet their front Calipers are mounted on opposing sides of the disc. Only the fronts were swapped, the rears were all set on the front of the disc.

Why would they be doing this?

[Kaz-kzukNA1]

For ordinary production cars, the biggest factor is the position of the steering rack/arm especially if using the multiple pistons big/thick caliper.
Just not enough space and thus, tends to place the caliper at the opposite side of the steering arm. It also needs to consider the reliable routing of the brake line and ease of service such as bleeding.

For the race cars (and some of the high performance cars), you will need to cosider it as a part of package and there are lots of things to be considered such as reliability, weight distribution, centre gravity, knock back, air flow/cooling, chassis/hub/sus stiffness, etc that will all affect the reliability, temperature control, chassis dynamics, cooling, etc and if you only focus on the brake, obviously the brake pedal touch.

Without knowing the test carried out, hard to come up with the reason but considering the weight/power/layout of Vanquish, probably it's something to do with the temperature control and more like front brake fade rather than overcool.
Just my guess.

Kaz

[goldnsx]

My guess is (from an aerodynamic point of view) that cooling may be better at 9 o'clock.

[NZNick]

I always thought that the front caliper is best at the 9 o'clock position, and the rear at 3 o'clock (looking at the drivers side) from a weight distribution / centre of gravity perspective.