Bleeding Brakes

I knew I had a brake problem - the rear drivers side brake was sticking.  Don't drive the beast but once a week, so was biding my time until I did a rear disc conversion.  Lately though, I noticed that the brakes (all of them) seem to be holding more.  About a week ago, just by chance, I happened to be looking in the general direction of the floor when I turned off the ignition.  I noticed that the brake pedal moved.  I restarted the engine and noticed that the brake pedal went down by itself.  That explained my problem.  With the high vacuum of idle, the brakes were holding the truck, but when driving (less vacuum), there didn't seem to be much problem.

Time for a new brake booster.  I was also going to replace the master cylinder because the lid seal was crap.

On to the real question...

Sunday morning I put on a new master cylinder and brake booster.  Piece of cake.  Was going real smooth.  Too smooth.  Got set up to do the bleed.  Crawled under the first corner, put the wrench on the bleeder screw, cranked too hard - bam!  Broken bleeder screw.  Started to drill it out when the rain came.  Project on hold while I evaluate my situation.

Two questions:
1. What size is the bleeder screw?  Various resources show different dimensions.
2. Should I just replace the whole caliper?

The front brake pads and discs seem to be in good shape.  I would assume the calipers are the original (now almost 35 years old).

New calipers aren't that expensive.  I can go to a lot of work getting the old bleeder screw out, and still have the possibility of screwing up the seating surface or the threads.

Just looking for a bit of feedback..

I vote for new calipers!  If the bleeder screw broke it'll be hard to get it out cleanly.  And calipers are cheap.  

baddog8it wrote

What size is the bleeder screw?  Various resources show different dimensions.

They vary.  Depends on who MADE the caliper, and who rebuilt it last, and if anyone ever stripped it or broke a screw in it.  It can be 1/4-3/8", or 6-10mm.  If you plan to replace one, try to match the tool size to the other one.

And I wouldn't be looking for (or even AT) cheap calipers.  That's not why these lasted 40 years.  Look for the BEST - see if you can track down a MotorCraft reman.

Thanks for the input.  I was leaning towards new calipers.  I'm just hoping that this project doesn't keep growing to the point where I'm replacing all the brake lines.

baddog8it wrote

I was leaning towards new calipers.

I'd be surprised if anyone makes these parts new; I'd be even-more surprised if anyone OUTside China is making them new.  I'd trust & prefer a US-made reman over anything imported.

What caught my attention was, "went for the first corner" If it was a caliper, did you go for the front axle first?

You should do the farthest first, that would be the right rear drum, then the left rear drum, then the right front caliper, then left front. but yes, new calipers are cheap, Not sure you could heat it up the try and get the broken bleeder.
Either way, auto parts store sell one-way-bleeders, get them, install them, love them.
 they save on much aggravation, and its now a 1 person job!

Replacing the brake lines isn't a bad idea, the hoses at least, if they are as old as the truck.
DOT has the year molded in or on a collar because the rubber hoses have a limited life even in a perfect world. (I know how imperfect the underside of my truck is)

Cupronickle tube can be bent by hand and is easily flared.
It will not corrode, and will likely outlast you.

Be sure to check the line up in the frame rail beside the gas tank.
IME, this is where they all rot, and of course it's inaccessible....

Rear axle lines seem to get it bad too, but at least they are out in the open.
If you do these, be mindful of Ford's 'better idea' to make the fittings at the hose junction/vent different size threads.

This is still in perfect condition, and its axle fittings are the same size:



It's not identical to a bullnose's, but it is interchangeable (assuming the axle lines match it).