My old ford is driving me nuts. I upgraded to dual piston front wheel cylinders and replaced the cylinders. Afterwards I bench bled the master (on the truck, but same procedure) bled RR, RL, FR, FL......still squishy. The pedal is hard on the second pump. If I place a cap on the single line coming out of the master cylinder it is completely solid. Any tricks to bleeding a 62 f100?

I can't find any leaks on the brake lines. On my old datsun it helped the have the front end raised and to tap the master cylinder while pumping the pedal. Nothing I have done seems to work.

I tried to use my mityvac, but am not really able to pull any fluid at the rear. My current technique involves pumping the pedal until it is hard and then opening the bleeder into a one man bleeder set-up.

 

I still find it easiest to have someone work the pedal while I work the bleeder screw.

 

I resorted to that as well. The wife pumps the pedal until hard, I crack the bleeder (the hose squirting into the one man bleeder set-up. No air coming out at the wheels. No obvious leak. Still really squishy.

 

Don't pump the pedal. Just have someone push on the pedal and you open the bleeder. Have the pusher tell you when the pedal goes to the floor then you close the bleeder and have the pusher release the pedal and apply pressure to it again and you open the bleeder til the pedal goes to the floor. Repeat as needed for each brake. Your sequence is right. Farthest from the master cylinder working to the closest. Remember to refill the master often because if you run it to low you need to start all over. Remember no pumping.

 

Can you clarify " ... upgraded to dual piston front wheel cylinders...". Did you change the master cylinder to a dual? If so, What kind and size is it? I know from looking through shop manuals that some of the bigger trucks had wheel cylinders with only one piston, but I think they had two cylinders per wheel.
My train of thought is that maybe what you changed needs more fluid or if you changed the master cylinder to a smaller dual type, it does not pump enough fluid as compared to the old one.

 

All the shoes need to be tight against the drum, with some wheel drag, or the pedal will be low and squishy, exactly like you describe. It doesn't take much to have a big effect. Best to bleed system with all adjusters/shoes up as tight as they'll go, depress pedal a few times to center shoes and hardware, and then back off adjusters as required.

Some new wheel cylinders (from you know where) are also reported to have been drilled at the wrong angle for the line port, and will not accept fluid because the piston covers the port.

 

Easiest way to bleed one-person is to run the drain hose from the bleeder UP and over the tire. Air bubbles that usually form at the nipple travel up and away from the opening. You can pump all you want and no bubbles will be drawn back into the valve. First time I did this I had my son do it while I went underneath to visually confirm that this is what happens. No special stuff needed. Just have to keep an eye on the master cylinder.

 

Here is a video on how to do it.

 

If you remove the regular bleeder screws and install a set of Speed Bleeders, you won't need one person to pump the brake pedal and another to open/close the bleeder screw.

With the Speed Bleeder, it has a spring-loaded check valve. Put your wrench on the bleeder, slip a tube over the nipple and down into a container, open the Speed Bleeder and pump the pedal to evacuate the air (keeping a check on the fluid level in the reservoir). The brake pedal can be lifted between pumps without having to close the bleeder in between pedal cycles, since the check valve will close and not allow air to be drawn into the brake system.

 

If the bleed line goes UP no special bottle is needed, just an open container. Even with speed bleeders, there is a small bubble that can stay in place just at the interface and get sucked back up and into the cylinder. Bubbles go up, so run the line up and away from the valve.

 

Thanks for all the follow up everyone.

Clarification 1....the truck came with single piston wheel cylinders in front. I bought dual piston wheel cylinders and a couple of cylinder pins so that I could run a less chincy hydraulic set-up. I still have the original master cylinder.

Last night I tightened up the front adjuster as far as I could take it and tighted up the rears quite a bit. Now the pedal is rock hard. Unfortunately I didn't get a chance to back the drag down to proper levels before going to bed.

The manual I have states to back off 10-12 clicks up front, but I felt like that was too much drag. My rears had light drag before and drag pretty hard at the moment. I put the self adjusting kit on them so I am not really sure how tight to set them before running it.

 

The main thing is to take up all the clearance in the system by running up the adjusters all the way and then back off the adjusters till a light drag on the wheel. That way you're coming at it from the other direction. Are the drums new? How many times have they been turned?

It's probably tougher to get a good brake right away these days, if for example the drums have been turned a few times, as they are now somewhat oversized but, the shoes installed are likely not. Since the majority of braking power is performed by the front axle it's worth taking the time to get this right.

Brake shops in the days of yore would install oversized linings to compensate for this, as well as using a brake shoe arcing machine to closely fit them to the drum. New replacement linings available today, installed in well worn, turned drums may not make good contact over the entire surface of the drum arc, as well as result in a low pedal.

 

The rears have been turned at least once (I had it done when getting new shoes). The front shoes were in good shape so I left them and am not sure if the drums have been turned or not. The truck had onlu 60k miles on it so they could've been original still.

It was a friends grandfathers farm truck so it spent a long time sitting.

I will try to get the drag set on these tonight.

On another note, I am using a set-up like in Monson's post.

 

I got everything adjusted out quite abit and now have a very firm brake pedal. I was going to test it all out and went to start the truck. It now seems like my stop light switch is stuck in the on position. It somehow managed to get hot enough to smoke the wire for a second.

 

It worked, thanks for the help. While I was at it I swapped out the brake switch and that seemed to fix the stuck lights.

Coincidentally, my dash lights worked for 30 seconds last night and then poo'd right back out.