1966 GMC Suburban front disc brake conversion

[Baketown Scotty]

I am converting to front disc brakes and have some questions. Removed closed knuckle Dana 44 and installed a Dana 44 with discs from a 1985 4x4 blazer. My sub is 4x4 as well. Is the power booster I have original to my sub? From what I have read I will need a new master cylinder for disc/ drum. Then I will need a pro portioning valve and new brake lines and then get a push rod from booster to master. I may need a new push rod from brake pedal to booster as the brake pedal is really close to the floor. Am I on the right track?

[Captainfab]

Yes that booster is original to your Suburban. And yes you will need a disc/drum master cylinder and a prop valve. That booster has the long intermediate pushrod which makes finding the correct master cylinder a little difficult. The first one that comes to mind is the '67-'76 Corvette master. Even though those are designed for a disc/disc application, many use them with a disc/drum system. The Corvette master cylinder is basically what most aftermarket boosters are that are sold for these trucks.

The alternative would be to replace the long intermediate pushrod with a short one and then you have more choices for a master cylinder.

[Baketown Scotty]

Thank you Captain. I'll get the search going. There is a plate between booster and firewall that makes the master point over to the drivers side. This could make plumbing in the prop valve snug to the inner fender. Thanks again.

[Baketown Scotty]

I checked Carquest and Autozone and they both have the Corvette master cylinder with 1-1/8" bore. The old master cylinder is 1-1/2". Will that be a problem?

[1966burb]

Just finished up the disc brake swap on my 1966 Burb that had factory power drum brakes. Push rod length was ok. I checked the hole depth on old master cylinder compared to new one. Proportioning valve bracket had to be shortened and "tweaked" a little. I had to remake both short lines from master cylinder to proportioning valve. I plan to hide to proportioning valve down in the frame someday when I pull the engine out. I used a ECE disc brake kit.

[Baketown Scotty]

Just ordered a master cylinder from Autozone (new $27) and the proportioning valve from ECE. ECE said I would be getting a brass one like 1966Burb's picture, not the cast iron one from Delco shown on line. Now need to get a double flare tool and get it all installed. Thanks all.

[Baketown Scotty]

Since the master cylinder I am buying was originally for a disc/ disc setup, will the front outlet of master cylinder go to front brakes and rear port to rear brakes? Or is it reversed as I have read on some other threads? The master cylinder I am buying from Autozone is part number NM1372.