Well, after a long hiatus, I got back to doing some work on my US6. Yesterday, I put a battery in it, started it up, and backed it over in front of the shop. Then I mowed the tall grass that had grown up around it.
I had been in the process of renewing the brake system. I crawled underneath to see what I had left to do. Just the master cylinder and the lines to the front axle. Seemed simple enough. I found my box of new hoses, and installed one from each front wheel to the tie points on the front axle. From there, hard lines run to a tee atop the front differential, and from there another flex line runs to a tie point on the front crossmember.
Well, I looked high and low, and simply could not find the special tee for the front axle, It has two inverted flare fittings to fit 1/4-inch line, and a special fitting to fit the crimped-on male end of the hose. And I know that the tee, with two pieces of hard line attached, is hung up somewhere in plain sight. But do you think I could find it? It was getting late, so I quit for the night.
Next day, I had a quick look for the tee, again without success. Then I thought to check the rear axle on a "parts" M16 out back. Sure enough, it had the exact right tee! First big break of the day. It wasn't long before I had the hard lines made, and a hard line from the front axle run right back to the master cylinder location.
Installing the master cylinder proved to be quite a struggle. I couldn't find the bolts to mount it (did find them later, heh), but that was no biggie; I have lots of bolts. It mounts to a plate welded across the inside of the frame rail, so you have to hold it up there, winkle a hand in between the frame rail and the plate, and then start three 7/16 NF bolts. Not to mention the fact that there is a heavy sheet metal yoke that straddles the master cylinder mounting points and carries the relay lever that ties the master cylinder in to both the pedal and the power assist cylinder. There had to be a better way. I cut the threaded ends off the three 7/16" NF bolts, and made studs of them, and put them on the "mount" side of the master cylinder, with the sheet metal yoke in place, and put two capscrews through the inboard side of the yoke and into the threaded holes in the master cylinder. I got it up in place and got 2 of the 3 nuts started easily. The third one, at the front, would not start, no way, no how. I used vise grips to back out the stud and replaced it with a capscrew, which started easily because the other two studs located the holes properly. While I had the yoke out, it was apparent that the relay lever was badly bent, as was the pull rod from the assist cylinder, so I straightened both of those with some hammer and vise work.
I got the 1/4" line to the front brakes hooked up OK, but the 5/16" line to the tandem rear axles had to come out and have an inch lopped off the "down" leg to the master cylinder. Fortunately, I had put a union in the line, so I could break it at the union. I got that one hooked up. Now for a stop light switch. I could not find the original, but I had a master cylinder from yet another M16 on the shelf, and it had a stop light switch in it. I pulled that off, and cleaned it up. It had what appeared to be two female bullet connectors on it, complete with spring wire latches. I screwed it into the elbow on the master cylinder, and clipped the munged-up old connectors off the wires, and crimped on two male bullet connectors. Guess what? They didn't fit the terminals on the switch! The I.D. of the sockets was too small for the bullets. I've run into this before. I clipped off the two male bullets, and made two slimmer ones by slitting standard ones with a hacksaw and crimping down the pin. They worked just fine. Finally the hydraulic system was tight to the atmosphere; I thought.
Filled the master cylinder with fluid, and tried to bleed the system with a vacuum bleeder kit. I wasn't having much luck. Found one bleeder screw loose on the rearmost axle, and one missing on the #2 axle, the hole filled by a plastic plug. Where to find a bleeder screw? Especially an oddball one like these. On a Sunday? Went back to the derelict M16. It had bleeder screws, alright, but front and rear were both too small, 3/8 instead of 7/16. So I went on a search, fully expecting I'd have to put a 7/16" screw in the lathe, drill it, and turn a conical end to make one. Anyway, I looked at the old '29 DeSoto "lawn ornament" I have, and would you believe it, it used the same bleeder screws!. Not only that, but I got one out in good condition. Still smelled of brake fluid. Second big break of the day.
So I got all the bleeder screws installed, and still had no luck bleeding it with the vacuum bleeder. I think with the large-diameter lines, all dry, there is simply too much of an air cushion for the vacuum bleeder to work. So I filled the master cylinder right up, and got most of the air worked out of it, and parked the truck back in its spot. Another day, I'll round up a helper, and bleed it the old-fashioned way. By the way, the vacuum assist unit seems to work OK. Brake pedal effort (against the return spring) was noticeably less with the engine running, and you could hear the engine rev up due to the vacuum "leak" caused by the assist cylinder.
So, all in all, a good weekend, and some significant progress made. I'm pretty certain once a proper two-man bleed is done, I will have excellent brakes, because I have already overhauled all the wheel cylinders, and serviced all the anchor pins, etc. There was plenty of meat on the linings, or else I replaced them. Kind of forgot, right now.
I had been in the process of renewing the brake system. I crawled underneath to see what I had left to do. Just the master cylinder and the lines to the front axle. Seemed simple enough. I found my box of new hoses, and installed one from each front wheel to the tie points on the front axle. From there, hard lines run to a tee atop the front differential, and from there another flex line runs to a tie point on the front crossmember.
Well, I looked high and low, and simply could not find the special tee for the front axle, It has two inverted flare fittings to fit 1/4-inch line, and a special fitting to fit the crimped-on male end of the hose. And I know that the tee, with two pieces of hard line attached, is hung up somewhere in plain sight. But do you think I could find it? It was getting late, so I quit for the night.
Next day, I had a quick look for the tee, again without success. Then I thought to check the rear axle on a "parts" M16 out back. Sure enough, it had the exact right tee! First big break of the day. It wasn't long before I had the hard lines made, and a hard line from the front axle run right back to the master cylinder location.
Installing the master cylinder proved to be quite a struggle. I couldn't find the bolts to mount it (did find them later, heh), but that was no biggie; I have lots of bolts. It mounts to a plate welded across the inside of the frame rail, so you have to hold it up there, winkle a hand in between the frame rail and the plate, and then start three 7/16 NF bolts. Not to mention the fact that there is a heavy sheet metal yoke that straddles the master cylinder mounting points and carries the relay lever that ties the master cylinder in to both the pedal and the power assist cylinder. There had to be a better way. I cut the threaded ends off the three 7/16" NF bolts, and made studs of them, and put them on the "mount" side of the master cylinder, with the sheet metal yoke in place, and put two capscrews through the inboard side of the yoke and into the threaded holes in the master cylinder. I got it up in place and got 2 of the 3 nuts started easily. The third one, at the front, would not start, no way, no how. I used vise grips to back out the stud and replaced it with a capscrew, which started easily because the other two studs located the holes properly. While I had the yoke out, it was apparent that the relay lever was badly bent, as was the pull rod from the assist cylinder, so I straightened both of those with some hammer and vise work.
I got the 1/4" line to the front brakes hooked up OK, but the 5/16" line to the tandem rear axles had to come out and have an inch lopped off the "down" leg to the master cylinder. Fortunately, I had put a union in the line, so I could break it at the union. I got that one hooked up. Now for a stop light switch. I could not find the original, but I had a master cylinder from yet another M16 on the shelf, and it had a stop light switch in it. I pulled that off, and cleaned it up. It had what appeared to be two female bullet connectors on it, complete with spring wire latches. I screwed it into the elbow on the master cylinder, and clipped the munged-up old connectors off the wires, and crimped on two male bullet connectors. Guess what? They didn't fit the terminals on the switch! The I.D. of the sockets was too small for the bullets. I've run into this before. I clipped off the two male bullets, and made two slimmer ones by slitting standard ones with a hacksaw and crimping down the pin. They worked just fine. Finally the hydraulic system was tight to the atmosphere; I thought.
Filled the master cylinder with fluid, and tried to bleed the system with a vacuum bleeder kit. I wasn't having much luck. Found one bleeder screw loose on the rearmost axle, and one missing on the #2 axle, the hole filled by a plastic plug. Where to find a bleeder screw? Especially an oddball one like these. On a Sunday? Went back to the derelict M16. It had bleeder screws, alright, but front and rear were both too small, 3/8 instead of 7/16. So I went on a search, fully expecting I'd have to put a 7/16" screw in the lathe, drill it, and turn a conical end to make one. Anyway, I looked at the old '29 DeSoto "lawn ornament" I have, and would you believe it, it used the same bleeder screws!. Not only that, but I got one out in good condition. Still smelled of brake fluid. Second big break of the day.
So I got all the bleeder screws installed, and still had no luck bleeding it with the vacuum bleeder. I think with the large-diameter lines, all dry, there is simply too much of an air cushion for the vacuum bleeder to work. So I filled the master cylinder right up, and got most of the air worked out of it, and parked the truck back in its spot. Another day, I'll round up a helper, and bleed it the old-fashioned way. By the way, the vacuum assist unit seems to work OK. Brake pedal effort (against the return spring) was noticeably less with the engine running, and you could hear the engine rev up due to the vacuum "leak" caused by the assist cylinder.
So, all in all, a good weekend, and some significant progress made. I'm pretty certain once a proper two-man bleed is done, I will have excellent brakes, because I have already overhauled all the wheel cylinders, and serviced all the anchor pins, etc. There was plenty of meat on the linings, or else I replaced them. Kind of forgot, right now.
We've got to quit saying, 
Not to mention, I didn't look at your profile until now. See you there, then.
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