Spongy brakes.....still.

Hey guys I know I dont get on here often that much anymore but I think last year or the starting of this year my dad and I changed the rear shoes and that's where this problem I think happened we've bleed the rear brakes many times.  We also changed the booster thinking that was the problem and it helped a little bit but still no cigar the brakes it stops but the pedal still goes almost to the floor.  We dont drive this particular truck often (1986 ford f250 4x4).  But usually gets out  in the winter because of the snow.  Me and my dad cant pinpoint this problem I almost positive the master cylinder is wore out.  Wanna fix this problem before I pull the engine  and fix the leaks.

Several thoughts.  First, did you adjust the shoes in the rear?  Maybe they aren't tight enough?

Second, someone on here had a problem with soft brakes and wound up making a pressure bleeder and was able to get the air out that way.  You could search for that thread.

Last, there's an adjustment between the master and booster.  And if it isn't adjusted properly the pedal can go way down before the brakes come on.  The instructions on adjusting it are at Documentation/Driveline/Brakes and on the Master Cylinders & Boosters tab and then the Push Rod Adjustment tab.

For the adjustment would I have to make a tool like the one they use in the manual or could I use a could of rulers?  

I did it with a dial caliper, but on the first try it was slightly too long and the brakes dragged.  Don't do that.

I was told by an old timer once how to adjust rear drums and it works well.

Shoes in enough to get the drum on, install the wheel. Tighten the shoes until you can’t roll the wheel anymore.

Loosen the shoes while counting how many clicks or how many times you move the adjuster, until the shoes don’t rub anymore. Tighten the other side till it won’t move then take the adjuster out the same amount.

IIRC it’s about 20-30 clicks.

Gary Lewis wrote

Several thoughts.  First, did you adjust the shoes in the rear?  Maybe they aren't tight enough?

Second, someone on here had a problem with soft brakes and wound up making a pressure bleeder and was able to get the air out that way.  You could search for that thread.

Last, there's an adjustment between the master and booster.  And if it isn't adjusted properly the pedal can go way down before the brakes come on.  The instructions on adjusting it are at Documentation/Driveline/Brakes and on the Master Cylinders & Boosters tab and then the Push Rod Adjustment tab.

Yep that was the only way to get the pedal to come up.

As others said adjust the drum shoes first. I get them to drag pretty good them hit the pedal a few time as this will center the shoes in the drums and check the adjustment again till they just start to drag.

Now I did all that, had my wife help bleed the system front & rear and still a low pedal.
I made a pressure bleeder using 3" PVC pipe & cap(s) an old master cap (should come up with something better for the next time) with a screw it tire valve (core removed) and regulator / gauge for shop air to the PVC.
Filled the PVC pipe with brake fluid and put 10 psi from shop air.
I started at the rear and did see a little air but I did not think it was much, no air out the front.
Well as soon as I pushed the pedal I know it was good.

Oh I also changed the booster & master to try and fix this before the psi bleeding.
I used a tape measure as the book calls for almost 1" and I figured just a hair under would work and it has.
At first I was too long, master would not sit flush to booster, thinking that may get the pedal higher it did not.


Dave ----

one day I will take better pictures and put it in the garage / tool area