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11/12/23: I continued installing my Power Disc Brake upgrade by installing the vacuum booster line to the manifold. I used 3/8” CuNi Tubing and a length of 3/8” gas hose. I bent a 180° loop at the firewall 6” higher than the manifold, to act as a barrier preventing raw gas getting to the booster. I then ran it down the firewall to a bracket I fabricated attached to the bell housing to secure the line. From there I used about a 2’ length of 3/8” gas hose to the booster. Bending up the tubing to get it closer to the booster was near impossible so I settled for the remaining 2’ to be hose. There was just too much stuff in the way.

Shifting my efforts to the rear tranny mount, I placed just behind the tranny and slid it in as far as I could before it hit the MC. I marked it where I felt would be adequate clearance then removed the crossmember. It actually slid under the MC so not allot was going to be cut out. To make the cutout, I first drilled thru the crossmember with a 5/8” drill thru both sides to get my radius corners so as not to create any stress cracking caused by square corners. I used a wafer wheel and a saws-all to cut a wedge out of the sides. Heated the top plate cherry red at the bend area and folded it down. I added a plate on the side and welded it up.

I spent the next hour just cleaning the crossmember up getting the 70 plus years of grime off getting it ready for paint. A little satin black paint, and it was ready to be installed.

I also sand blasted the mounting hardware as they were pretty crusty themselves. There are ten 3/8”x24 bolts with nuts and lock washers, that hold in that support and four more securing the mount to the tranny, all for a crossmember that many say is not needed. A bit of GM engineering overkill I think.

In order to try out the new brakes, I needed to put the front wheels back on. The passenger side went easy as I had already checked the clearance but the drivers side wheel locked up before I got the lugs on. The dreaded caliper to wheel clearance issue. I looked at the other two rims but they would not work either. After checking, I have three different style rims on my truck.

Now the dilemma, do I just try replacing the one rim so I can test out the brakes or all the rims? My original plan was to wait until I painted the truck and buy new 16”x6” rims and new Coker wide white wall radial tires with stock hubcaps and beauty rings, close to a two thousand dollar investment. Not something I wanted to do now. Here is a link to the issue in the Driveline forum.

11/13/23 Today I installed the rear tranny crossmember which completes the Power Disc Brake upgrade. It went in easily but took a bit of time aligning and installing the fourteen bolts which fasten it to the frame and tranny. The clearance looks perfect and I am happy with the results. I reinstalled the battery so we are ready to test it’s stopping power as soon as I resolve the rim issue!