Some C4 rotor questions

[Supercharged 86]

Time to start thinking of brake upgrades. I have it mostly planned out, but there are a few simple questions left. Those questions would be...

-what is the thickness of C4 Vette HD rotors?
-what is the diameter of the rear C4 HD rotors?
-does that same rotor use an internal parking brake or a caliper parking brake?
-is there a reasonably priced aftermarket source for sloted C4 HD rotors?

The currnet plan is Wilwood FSL 4 piston calipers all around (what piston size with a 1 1/8" MC?), 13" slotted C4 HD roters up front mounted to Blazer/S10 spindles with integrated wheel bearings, and slotted C4 HD rotors out back with a custom braket to mount to the rear. I guess I'll need an adjustable proportiong valve to set it up correctly even though I already spent the bucks for an Inline Tube PV specially made for 4 wheels discs.

Any comments or answers? This is for an '86 El Camino by the way. Thanks!

[Supercharged 86]

OK, I've answered most of the questions, but can anybody comment on piston sizes for the Wilwood FSL calipers? I'm thinking 1.38" all around, but am wondering if they should be bigger, smaller, or the same size for a 1" smaller rotor in the rear.

[rambling]I'd think that a larger piston would not grab as hard and make me have to press down farther on the brake peddal (already low) so maybe I should get 1.38" pistons all around like I was saying and get a $30 adj. prop. valve to fix any problems as long as I need less pressure in the rear. It goes on and on...[/rambling]

[dustinls1]

I would recommend you use 1.75 pistons up front and 1.25 pistons in the rear, and yes an adjustable proportioning valve will take out any further rear brake as required.

If you have a lot of pedal travel using a 1.12 bore master cylinder, I suspect you have a problem elsewhere in the vehicle, most manual set ups use 1 inch master cylinders, and power uses 1.12 to give an artifically high pedal with the booster.

[Supercharged 86]

Thanks for the reply. The car came with a 1" MC stock. When I went from t5he stock disc/drum to disc/disc, I think it required more fluid to be displaced and the 1.12" MC did help considerably. I think the real problem may have something to do with the front and rear brakes being EXACTLY the same right now.

So what exactly is the reasoning behind bigger pistons up front than in the rear, just proportiong (I guess bigger pistons are harder pushing?)

I have almost everything figured out now except where the money will come from

[dustinls1]

brake torque is a mathematical equation based on rotor radius, pad friction, hydraulic pressure and piston area. effectively, bigger pistons = more brake torque. inertia is always working against you, transferring weight to the front tires, which is why you want more front brake than rear.