Thoughts on master cyl.
 

I will be installing OEM disc brakes on the Z, I am planning to change the drum brake master over to a Trans Am disc brake master, thinking that the metering should be sufficient to work the rears. I'm not using T/A brakes or Eldorado calipers, I sourced an 11.5" set from a "98 Bravada. The piston size is a bit larger than the T/A pistons. Just asking y'all if my reasoning regarding the master is sound. The combination valve should not make a major difference, as, I am unable to obtain a T/A valve new. my plan here is to have no aftermarket wear items on the car. Thoughts and opinions are welcome.

Here is what I know. Or should I say, what I can copy and paste. The reason for the odd ball caliper and backing plate deal is because of the staggered shocks. I was going to do this but went with Camaro 12" set up instead.
Parts you will need:

• 1 - Driver side 4WD backing plate, e-brake assembly (GM PN-15064302)
• 1 - Passenger side 2WD backing plate, e-brake assembly (GM PN-15773309)
• 8 - 3/8 bolts, lock washers and nuts to mount backing plate to rear housing
• 3/8 washers to shim the backing plate for perfect fitment of the caliper to rotor (2 each bolt in my case)
• 2 - Driver side 4WD caliper, or passenger side 2WD caliper, mix & match (Loaded kit w/ brackets & pads Cardone PN-164712) (Loaded kit w/ brackets & pads NAPA PN-TS 1422228)
• 2 - Caliper brackets - if needed
• 1 - Brake pad set - if needed (HAWK HB119F-594)
• 4 - caliper bracket bolts (GM PN-15726460)
• 2 - banjo bolts (GM PN-10286122)
• 2 - 2WD Blazer rotors (NAPA 4886725) (Powerslot 8638PSL & 8638PSR)
• 1 - Master cylinder (80 disc/disc T/A, 79 disc/disc Vette, 70 manual disc/disc Vette all work)
• 2 - Brake hoses (you can use stock Blazer hoses or any braided stainless ones with a 10mm banjo fitting)
• 1 - Prop valve (stock 80 T/A works, I used a Summit adjustable)
• New style brake cable (I used the Blazer cables, but Lokar universal would be less work)
• Brake fluid, gear oil, axle seals

Rotor Specs
Outside diameter: 11.61"
Height: 2.87"
Thickness: .79"
Mounting face to friction surface: 2.08"
E-brake surface diameter: 7.5"

Caliper Specs
Aluminum
Single 1.875" piston
Floating

Keeping it factory parts is a great idea, especially if you keep track of what all the parts are like Damon has done, so in the future you can just look up your records and see what you need.
The master cylinder size, shape, etc. is not all that critical with disc brakes as they ride on the rotors and don't take the volume from static to full lock up that a drum wheel cylinder does. I'm running a tiny little Subaru master on my gasser with GM metric disc and GM drums rear, and it has plenty of fluid to work the cylinders. It was also a proportioned 4 wheel disc, ABS system, but I didn't use any of the ABS and installed an aftermarket proportioning valve. That's the only thing you may end up adding to your system. After driving the car you'll know soon enough if you need a proportioning valve to make it brake correctly, and then it's pretty simple to cut one in if you've got a tubing cutter and flaring tool.

I've had it all mocked up on one of my other axles. I'm starting to think I may have to adjust the rear bias. I've done a number of 8.8 conversions on TJ's and YJ's and never had to worry about it. Explorer disc brakes work perfectly with the Jeep system. It's kinda got put on the back burner for the moment, I'm gearing up for the trucks new suspension, and I still need to rebuild the rear end in the car.

This is what I had mocked up.

Attachment 25321

Well it looks nice!

Wow , first time I've seen someone use new parts.

That's pretty much how I roll now. Used parts around here mean used up. I got all the components from the junkyard for $50. The calipers were locked up and the ebrake shoe was totaled, and since rotors are usually past minimum when machined, I always replace them. I don't like doing it the first time, I certainly am not going to want to do it again a month later.

All my rear stuff came off Ebay. They were in good shape. My ls front brakes had 20,000 miles on them and the guy sent them to me for shipping. I couldn't pass them up. I'm waitin on access to a lathe before I can finish them.

Yeah, that's a good deal. Going new meant that I could mock it up that weekend and I also have lifetime warranties on all the components, the receipts are marked and filed. I won't be paying for replacements. The last time I tried, my computer wouldn't accept a return. I have business accounts at the local parts stores, that helps with the cost.

You ever see a ls front swap?