Front/rear disk brake sizing and calipers?

[HellTriX]

Im trying to get the smaller details of my suspension work out of the way now so I can focus on actual suspension setup.

I want to run 18 inch wheels both front and rear in my car, 10 inch wide in the rear and 8-9 inch in the front. This makes me unsure of what size brakes I will need. This is for a 66 impala not exatcly sure of the weight balance but I plan to measure that, was just waiting for the final details in the motor work to be done as it will change the weight a bit.

I'm wanting to use 13 inch rotars in the front with a 2-4 piston caliper (I dont know what size pistons yet). I was thinking of 12 inch rotars for the rear, but then I see lots of other combos that use nearly the same size rotars front to rear.

So I guess what I am asking if there are some formual I can use to calculate a general idea of size of roters and clamping froce of the calipers along with some of the weight transfer etc.

Tnx

[dennis68]

There is no formula, the key is not over-brake the rear. There is no reason not to run same size rotors front and rear, just make sure the rear calipers are much smaller and then tune with an adjustable prop valve.

It would be difficult to have any kind rule-of-thumb as there are way to many variables. ie. f to r weight distribution, suspension design and effectiveness, amount of anti-hop in rear suspension, amount of anti-dive in front suspension, spring rates, tire size and tire size differences f to r, master cylinder design, manual brakes vs. power brakes, intended purpose of chassis-the list goes on but that’s the idea.