BRAKES III
When I removed the MC, I damaged the rear MC-to-DB line. I couldn’t find a seller for this one prefabricated line (lots of kits available, but no onesy-twosies). I also had a kinked line in the rear that needed attention (I couldn’t find this individual piece prefabbed, either). I decided to make my own lines and bought a flaring kit, bending tools, brake line and some fittings. I’m glad I went this route because later I needed to make a pump-to-carburetor fuel line. I bought short lengths of both cunifer and steel tubing so I could experiment. I practiced by making several flares and bends. I didn’t find a huge difference in working the two types, although steel seemed slightly easier and is a lot cheaper. When I made the real line, I checked my bending radii closely and used a piece of 14 gauge copper wire (from a piece of Romex, the kind used in your home, easy to bend to shape) to mock up routing. I managed to get a decent looking, good fitting line on the second attempt. I made the MC line from cunifer.
I bench bled my new MC, installed it, and bled the whole system once again. Considering how dirty the original fluid was, more bleeding (and consequently, more flushing) wasn’t a waste. But, by this time I had made several trips to O’Reilly’s to replenish my supply of brake fluid. I should have bought a gallon right off the bat instead of smaller containers. After a few bleeds, I made a calculation of the approximate capacity of the lines so I would know when I had displaced all the fluid in the line instead of guessing on how many pedal pushes or whatever. On my truck, from the MC to a rear WC is about 4.5 fl oz and from the MC to a front WC is about 1.5 fl oz. (including the common line). Using a plastic bottle with fluid ounce calibration marks on it for a receptor, I could see when I had displaced all the fluid in a line.
A PO had installed a trailer brake system (TBS) [Kelsey Hayes 81739, vintage unknown]. I found the wiring for the brake warning light had been modified and a hydraulic line had been added from the MC to the TBS controller in the cab. I first made a sketch of the existing wiring and then compared it to the schematic in the Service Manual. Then I removed the entire TBS system and got the wiring back in order. The brake warning light then came on like it should on Start (which it didn’t do before). I couldn’t get it to light up on Run when I’d hit the brakes with one bleed screw open. I tried opening both front and rear and I tried tapping the DB with a hammer, too. The internal shuttle that acts as a differential pressure switch must be stuck. No biggy for the moment (add to The List).
When I first contemplated doing this work, I realized that I hadn’t bled brakes in many years. Since that time long ago, the Internet arrived. So I looked at a lot of howto’s (and howto NOTS!) on YouTube, this site, and elsewhere. I thought these two were informative and entertaining.
At this point I had decent brake pedal so I fired up the truck and made a few tentative moves to back out of the garage. It felt OK, so out I went and parked it in the street. The fronts were doing their work now and it was the rears that needed help.