Opening up wheels/brakes/axles for projects, could use some parts selection help

[Uncle Gump]

The rear brakes are always being applied. The front brakes do most of the work though.

You said you also had a low brake pedal... having the rear brakes adjusted properly will also raise the pedal height.

 

[eightynine4x4]

Upon all of this inspection I’m assuming my rear brakes have been absolutely motionless in recent years. So if they’re always being applied by the pedal then I guess I’ll feel some significant difference when they’re actually operating. Even just adding fluid I should feel something.

This is the first time noticing the low fluid. Is it possible that brake fluid level can leak so slowly that it doesn’t seem like an actual leak anywhere? Like it’s slowly evaporating and not dripping?
I am ordering new cylinders since they are so cheap. I’ll probably just go right ahead and replace them since I have this all apart already and the likelihood of me needing to bled the system anyways is getting higher. Im guessing that my cylinders are in worse shape than my calipers and so just throwing new ones on while im here is a good idea since they might be causing the slow leak.

 

[Uncle Gump]

As the front brake pads wear... brake fluid level lowers to "fill the void" of the material that was worn off the front pads.

Unless you open the hydraulic system or can see leakage... there is no way air can get into the system. So chances are slim you will have to bleed the brakes.

 

[eightynine4x4]

As the front brake pads wear... brake fluid level lowers to "fill the void" of the material that was worn off the front pads.

Unless you open the hydraulic system or can see leakage... there is no way air can get into the system. So chances are slim you will have to bleed the brakes.

Ok gotcha. Then what I’ll do is keep the new cylinders on hand but reassemble the system with old cylinders and add some fluid and see if the old cylinders work and if they do then I guess I’m good to go.
I will have to run the engine correct?

 

[Ranger850]

From what I can see in those pics. The Cylinders in post# 66 look good. Dirty, but good. No fluid dripping from the boots and the rubber looks to be in good shape. Fluid loss is probably what Uncle Gump explained about pad wear.

 

[pjtoledo]

you need to check the pistons inside those cylinders to see if they are moving., and inspect for rust.

if the pistons are free you should be able to push on one piston and the other will move out the same distance.
there will be some resistance from the internals, it should be smooth.
if they don't move remove the donuts to inspect for rust.
the donuts are not seals, just dust covers. the actual seals are part of the pistons.

a word of caution, there may be a spring inside the cylinder putting mild pressure on the pistons.

"back in the old days" we used to open up the cylinders, run a hone thru them, clean stuff and reassemble.

 

[Uncle Gump]

If you have new wheel cylinders... I would just put them on.

I was simply describing what you refer to as fluid loss and your thoughts on bleeding brakes.

I would hate to see you do all the work only to develop a fluid leak at the old wheel cylinder.

 

[eightynine4x4]

If you have new wheel cylinders... I would just put them on.

I was simply describing what you refer to as fluid loss and your thoughts on bleeding brakes.

I would hate to see you do all the work only to develop a fluid leak at the old wheel cylinder.

Is changing a wheel cylinder with the axle shafts back on a total pain? If not, I may just stick with the old cylinders and see if everything seems fine before opening up the fluid system and having to risk a whole can of worms with that. If I discover a bad cylinder after the truck is back together, and it’s not extra work to replace a cylinder with the axle shafts on, I’m fine with then having to replace it and deal with the fluid air/bleeding. But if it’s a totally worse ball game to replace cylinder when axle shaft is on then maybe I do both cylinders now and learn how to bleed the system.

 

[Uncle Gump]

Piece of cake...

 

[eightynine4x4]

Great thanks.
I saw in Haynes that brake fluid types “(3/4/5)” should not be mixed. What is the most likely type that a place like Mavis would have filled the system with after bleeding? I’ll be grabbing some more today.

 

[pjtoledo]

3 & 4 are compatible.
dot 5 is silicone, don't use it.
dot 5.1 is compatible with 3 & 4

check any parts place for descriptions.

 

[Eddo Rogue]

If you are doing the front and its a TTB, there's a way to grind away some material around the u joints so they don't bind from steering in 4wd. Theres extra meat on there, so it wont hurt integrity. While in there maybe check/swap the steering u joints.

 

[eightynine4x4]

If you are doing the front and its a TTB, there's a way to grind away some material around the u joints so they don't bind from steering in 4wd. Theres extra meat on there, so it wont hurt integrity. While in there maybe check/swap the steering u joints.

Doing front after rear is done, thanks will look into it! Am wanting to do u joints up there anyways but not sure how much i want to do at once. As of now they function but click a little as they rotate.

 

[Eddo Rogue]

I would do it all at once, so you're not taking it apart twice. Otherwise start from the inside and work your way out. Like do the diff/axles/u- joints etc first, then deal with whatever you can do with without having to pull the axles/diff cover apart again ( like brakes, wheel bearings etc). Got the same job due here actually, and waiting until I have the time and all the parts gathered to do it all in one shot. I hate double work.

 

[don4331]

Upon all of this inspection I’m assuming my rear brakes have been absolutely motionless in recent years. So if they’re always being applied by the pedal then I guess I’ll feel some significant difference when they’re actually operating. Even just adding fluid I should feel something.

This is the first time noticing the low fluid. Is it possible that brake fluid level can leak so slowly that it doesn’t seem like an actual leak anywhere? Like it’s slowly evaporating and not dripping?
I am ordering new cylinders since they are so cheap. I’ll probably just go right ahead and replace them since I have this all apart already and the likelihood of me needing to bled the system anyways is getting higher. Im guessing that my cylinders are in worse shape than my calipers and so just throwing new ones on while im here is a good idea since they might be causing the slow leak.

As noted, as the pads wear, the fluid level decreases to compensate.

But you can also have leakage on the side that had the axle leak - the major oil leak hiding a minor brake leak.

It is easy enough to change a cylinder later, that you don't need to do it right away, if the test of pushing pistons is a success. The other test you can do is: Before you install the brake drum, put a tie down strap around the brake shoes (firmly, but not overly tightly). Then have assistant gently press on brakes, while watching to see if strap gets tight. Note: You want the drum installed on the other side...there nothing worse than nothing happening where you are watching while the other side spits itself all over. Tie down strap allows a you to watch for movement without concern that it will eject the pistons.

How much the rear brakes works, sort of depends on how you use your truck:

My daughter's truck run empty 99.9% of time, so the rear brakes do very little.​

My truck pulls a 5th wheel about 10% of time (very close to max GAWR on rear; trailer brakes ensure rear wheels have lots of weight), so I definitely work the rear brakes.​

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One of the challenges for Ford Engineer's - a sliding wheel has less friction than a rolling one. With significant difference in rear axle weight between empty and loaded, it is challenging to get good performance when loaded but not lock up when empty. Back end passing front because the rear wheels locked up when you hit the brakes in a corner is a control nightmare. So, Ranger's rear brakes are undersized to keep Ford's lawyers happy (And why they added RABS).​