Finally finished the disc install

[ERASER5]

I am finally all done with the disc brake install on the 70 GMC. My parts are standard off the self stuff except for the 6 lug McGaughy rotors, the 10# residual valve from Master Power Brakes and the stupid banjo bolts. I may post some pictures later, but there will not be any thing fancy.

I used the 73-87 donor method with a Disc/Disc or Disc.Drum MC and 7" dual diaphram booster. I can now for the first time lock all four wheels up!

I had a few bumps in the road, but I learned a lot of small details. For instance, in 1979, GM changed from a 7/16-20 banjo caliper bolt to a 10mm banjo caliper bolt. I just happened to pick "1978" as the reference year for all of my brake parts. None of the box stores carry or even list a 7/16-20 banjo bolt. Only the 10mm for about $3.00. I had to special order my bolts on line for $10ea plus shipping. Another delay.

The firewall MC boot/grommet for manual brakes will not work for the power brake setup. Had to order it and wait.

My Power Booster/MC came with no instructions, so I had to look at my 72 (lucky me) and take some measurements. To get the final fitting, I had to cut 3/8" off of the booster "input" rod to get it short enough and on the MC side, I had to trim the bolt face that hit the MC so as to let the MC retract all the way.

My e-bay MC did not work on the rear section. I pulled the snap ring out and removed the rear piston and found chunks of junk in it! The piston was not able to refill. So I cleaned, cleaned, wiped and re-wiped, then re-assembled the MC. Fixed that.

I used the later model brake lines, putting the proportioning valve at the front crossmember. I will not be doing that again. What a pain to install the lines and then bleed! I also learned about the valve locking the rear brakes out (brake light comes on all the time) and how to re-center the valve using the bleed screws.

Oh, and due to my MC, I needed to install a 10# residual valve in the rear brake line.

The truck has shiny new painted front suspension, steering, and disc brakes and fresh alignment.! So now I am happy! Or grumpy, or dopey or one of those guys.