did you have any compromises with the pedal feel? was the bias affected at all (premature lock up on the front or rear)? did you guys end up swapping the master cylinders for the z32 unit? i'm having second thoughts about buying the top of the line rotora or stoptech kit. so i'm giving the z32 setup one more chance. this setup is plenty for an S13 that only weighs about 2,500 lbs right?

 

I just tried the Z32 calipers and realized that the wheel offset of the stock rims is all wrong to make these things work. Not to mention that the Z32 rotors are 280mm x 30mm but the A33 (5.5 gen) are 295mm x 24mm .

 

good question I hope to be able to answer soon.... one of my 300ZX buddies just upgraded his Z to the 30mm Z brakes...off a parts car we had axcess to and is giving me his 26mm Z brakes.... I know there was a write up on this swap somewhere... but I have been unable to locate it.... pedal feel and brake bias will come down to how much fluid the master has to move for the Z brakes vs the stock brakes

 

The Z32 brakes make the car quite a bit more front biased, but I haven't had any problems with it yet.. if you really want to fix it, throw in a brake bias adjuster and you can dial back the fronts a tad until the rears catch up. (or stay tuned for a rear brake kit that should fix the bias without dealing with bias adjusters).


As for how MUCH it shifts to the front.. it's a simple matter of hydraulics and moment arms...
your stock front brakes have 11" rotors (roughly), and a single 2.25" piston. the Z32 brakes have an 11" rotor with four 1.5" pistons.

the moment arm on each is about 4.75"... you can just approximate by measuring from the center of the wheel to the center of the brake pad. (the rotor is 11" diameter, which is 5.5" radius.. the pads are about 1.5" wide, so the middle is .75" in from the edge of the rotor- 4.75")

it's roughly the same for the Z32 caliper and for the OE caliper on the arm..

Soo, what makes the Z32 brakes fun are the four 1.5" pistons, compared to the single 2.25" piston.

assume your hydraulic pressure is 100psi..
that means the clamping force exerted on the rotor is the piston area * fluid pressure (since pressure is force over area)
OEm caliper... (2.25in/2)^2 * Pi * 100psi = 398lb clamping force

Z32 caliper.. (1.5in/2)^2 * 4 * Pi * 100psi = 706lb clamping force.

The rear pistons are 1.375" diameter. Let's ASSUME the line pressure is the same for front and rear, which it's not but it makes the math easier.

rear OE caliper = (1.375in/2)^2 * Pi * 100psi= 148.5lb clamping force.

Let's also assume the front and rear rotors are the same (they're close enough for these numbers, that way we don't have to take into effect different rotor diameters and triple the math)

Sooo, the factory front/rear bias is roughly 398/148 front/rear... that comes out to about 73% front.

throw the Z32 calipers on the front, and you're at 706/148 f/r... that's about 83% front.

biiig change.

Will the master cylinder help any? probably not. only thing you can do is drop the line pressure to the front, or put bigger calipers on the back to compensate.



Now, real world experience tells me that the Z32 front brakes don't really screw up the bias that much for daily driving. with sticky track tires (or even my not so stick street tires), I have no problems being able to tap the brakes in a corner and make the back end come around, and I've got even bigger pistons in my wilwoods and 13" rotors up front!!