[jarretts70]

I'm doing a rear disc swap on my 1970 GTO, using parts from a late 90's Blazer. This setup is pretty similar to the LS1 F-body brakes, with the "drum in hat" parking brake setup.

For now the front brakes are the stock discs, but these may also get upgraded to the LS1 fronts.

I installed an adjustable proportioning valve to the rear brakes.

I plan to run a stock 11" booster (fairly mild 455, should have plenty of vacuum).

Not sure the best choice of master cylinder. I would like to keep something that looks somewhat stock (no polished Wilwood or Chinese knockoffs...). My thoughts are c3 Corvette or 1979 WS6 Trans Am. I was leaning toward the T/A part; I figure my brake setup is comparable to a T/A, as is vehicle weight. Both masters are 1 1/8" bore; the Corvette uses two equal-sized reservoirs, while the T/A uses different size reservoirs like a disc/drum car. I'm not sure why, can anyone explain the reason & which master would be a better choice?

It's not exactly a hardcore track car or pro-touring thing, but it's being setup to handle & hopefully stop a lot better than 1970....

[gtospieg]

The size of the bore you need in your master depends on whether you are doing manual or power....1 1/8" is for power...1" or even 15/16" for manual.

[MNBob]

You are really going to like those Blazer rear disks! They were a definite step up in performance from my factory rear disks. Plus the parking brake works really well.

I used an 81 TA master and booster with my stock front disks. This has worked perfectly. The 79-81 dual diaphragm boosters are some of the best ever from GM and provide more clearance for valve covers. The 81 master is aluminum and weighs 1.6 pounds versus the 9 pound 79. The 81 master must be used with an 81 booster because the part that fits in the booster is larger.

Engine Left

[jarretts70]

Hi MNBob, thanks for the feedback! I like the looks of your setup & engine bay in general.