In lots of cars, it is possible to see the location of the brake calipers through the wheels.
Indeed in the majority of cases it seems the brake pads are always located towards the center of the car, i.e. rear of the front wheel, and front of the rear wheel:
Does the brake location being closer to center of mass have any effect on the physics of a car, in case of hard braking?
I think this is as much a mechanical engineering question as it is physics.
Pesonally, I have owned an Alfa Romeo car, which has the front disc brakes assembly at the engine end of the ( front wheel ) drive shafts, rather than at the wheel hub. This reduced the unsprung weight of the wheel assembly and allows the chassis, rather tnan the suspension system, to absorb the braking torque. The weight of the car is slightly reduced by this method.
Does the brake location being closer to center of mass have any effect on the physics of a car in case of a hard braking?
As I guess you know, the main effect to be avoided in the case of hard braking is the sudden transfer of momentum to the front of the car, there is a valve system in modern cars to spread the braking force evenly.
Compared to this requirement, putting say, the brake hubs at the far ends of the wheels has, i would imagine, relatively little effect, when you consider the mass of the car versus the mass of the braking system.
If I read your question correctly, you're asking whether, if we moved the brake calipers to the 9 o'clock position for the front wheel and to the 3 o'clock position for the back wheel, would anything change? In either case, the force which slows the car down is still applied at the point where the tyre and road are in contact, so I'm going to say no difference is made in this regard.
While there are probably some preferences on caliper position for specific performance, material cost, or cosmetic considerations, in general it does not matter where the calipers are located except for the need to keep the "bleed screw" near the 12 o'clock position.
The bleed screw is a special screw found on most modern brake systems which allows release of air or vapor from the brake system. The reason for the need is that air is compressible, so in modern hydraulic systems which rely on the incompressibility of the brake fluid to operate, excess air in the system would cause the brakes to be less effective or even fail.
