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

[don4331]

After all the dull, rust pictures we needed shades for that one.

He's just got to get everyone comfy with their new homes. Yes, the primary shoe needs to be seated against the top pin, then naturally the tab seats properly in the wheel cylinder

You want a strap around the brake shoes before you pump the brakes. Otherwise, you will eject the pistons from the cylinders and get brake fluid all over everything. And remember to pump softly - brake cylinder would be forcing the shoes against the drum hard enough to lock the rear wheels. You wouldn't want the strap to break.

 

[eightynine4x4]

Another look at what you have... the primary brake shoe doesn't appear to be seated properly in the wheel cylinder.

Yeah agreed, didn’t catch that when took the photo. However it’s just a matter of bumping it down a little. Will use a rubber mallet tomorrow to fine tune it.
Overall I am unsettled by how loosey goosey the assembly is. It seems to really just depend on the drum for staying in position. One can just push from the side and move the whole contraption around. Same goes for the other side. I tested that side for this before taking apart becuse I was like huh did I do something wrong?
This leads me to be concerned about one thing though.. should the surface of the inner plate be somehow treated or lubricated for the smooth motion of the inner edge of the shoes? I mean there is inherently a ton of friction there, making it difficult for the shoes to move this way or that. Like did they design the system assuming the inside face of the plate will be super smooth metal forever? Isn’t all that friction going to also make it hard for the springs to pull the shoes back away from the drums after driver let’s off the brake? Seems like they’d get stuck in weird positions all the time.
Or am I just not realizing how powerfully the cylinders push out and how strong the springs pull back.
Seems like a total waste of energy. Couldn’t there be pivot points and otherwise the shoes float away from all neighboring surfaces?

 

[Uncle Gump]

You typically lube the backing plates on the high spots. You only need a little.

The brake shoes should swing front to rear... that's how they self energize and self adjust.

Mind you... they shouldn't be sloppy lose.

 

[don4331]

On post 56 you can see the 4 spot (light rust) where the shoes sat on the backing plate - you need just a dab of high temp grease at those locations.

The brake line pressure might hit 1,200 psi from the rear drums, the piston is 0.75", so when you slam on the brakes, you are getting over 500 lbs forcing each the shoe against the drum.

And you only want the shoes just clearing the drums.

Part of the reason people think drums don't work, is they set the shoes up too loose. Then, before the shoes engage, the front pads have done all the work. In theory, when you apply the parking brake it is supposed to spin the adjuster to tighten the shoes, but too may people don't regularly use the parking brake. Put the auto in park and call it good. Adjusters tend to seize adding to the issue.

 

[eightynine4x4]

On post 56 you can see the 4 spot (light rust) where the shoes sat on the backing plate - you need just a dab of high temp grease at those locations.

The brake line pressure might hit 1,200 psi from the rear drums, the piston is 0.75", so when you slam on the brakes, you are getting over 500 lbs forcing each the shoe against the drum.

And you only want the shoes just clearing the drums.

Part of the reason people think drums don't work, is they set the shoes up too loose. Then, before the shoes engage, the front pads have done all the work. In theory, when you apply the parking brake it is supposed to spin the adjuster to tighten the shoes, but too may people don't regularly use the parking brake. Put the auto in park and call it good. Adjusters tend to seize adding to the issue.

Excellent info thank you.
Interesting about the parking brake. One of the reasons I’m focusing on this project is because I really want to have a parking / E brake for regular use. Good to know it’s supposed to be used frequently.
As for those points for high temp grease, hopefully I’ll be able to get some in the passenger side in photo, by shimming it all around a bunch but if I can’t I’ll have to undo it all and grease those points.
When I set the adjuster for the drum I’ll make sure to get them with close clearance.
As for the parking brake mechanics, I wish I understood it! If I have it installed correct, and the cable is pulling at the bottom of the special little floating bracket thing seated behind secondary shoe, and that bracket is pulling down/over the top of the secondary shoe at its connection point, then it must be using the secondary shoe to force the brass cross strut over and into to the primary shoe via a spring which forces the primary shoes against the drum. That’s the best I can make of it at this point.

 

[alwaysFlOoReD]

Not replying specifically to the parking g brake engagement. The small shoe is the first one to engage the drum when applying brakes. This forces the secondary shoe into the drum and where all the stopping happens, hence the longer shoe. The parking brake cable should pull the lever on its pivot point and spread the shoes engaging the drum. It's been a very long time since I've worked on mine so it's a little hazy. But you seem to be able to grasp the design pretty good, not many take the time to figure it out.

 

[eightynine4x4]

Back to rusty pics!
So here’s one of the drums. Cleary it hasn’t seen shoe action for a while. Other drum probably hasn’t either but due to my axle seal leak it has been covered in oil and been perfectly preserved!
I want to just spend a half hour attempting to refurbing this rusty one to save cost. Any harm in using a wire wheel on inside braking surface? Just not sure how much that will screw up the shoes if they make contact with a surface with a zillion zig zag scratches on it. Probably not much of an issue.
Another option is media blasting it. Would need to do it outside and let the media just fly off into the wind because I can’t have all this rusty stuff going back in through cabinet lines and through gun. Would make a smoother surface than wire wheeling though. But more time and effort and setup.
Maybe I just wire wheel inside surface and go over it with a 220 sanding sponge block.

 

[alwaysFlOoReD]

Wire wheel is good enough. Rough surface will help break in the shoes.
As a far as sandblast, what are you worried about? Contamination of rust? I wouldn't worry about that. Contamination of oil... I would clean that off with Brakleen or gasoline then sandblast.

 

[eightynine4x4]

Wire wheel is good enough. Rough surface will help break in the shoes.
As a far as sandblast, what are you worried about? Contamination of rust? I wouldn't worry about that. Contamination of oil... I would clean that off with Brakleen or gasoline then sandblast.

Ok great I’ll just wire wheel.
Sand blast this thing inside cabinet is a little risky because of this stuff coming off and possibly passing back through takeup lines and back through gun and clogging it. Blasting outside cab is fine of course just messy and a waste of media

 

[eightynine4x4]

Both brakes assemblies hooked up.
Axle shaft seals also mounted in and greased both on inside retainer spring and inner lip for axle shaft.
Next up will be thread chasing all the lug bolts on shafts since they have buildup of gunk and rust. Then will install them and attempt to get C clips in.
As for the O rings for c clips, I’m going to push the one in, thats currently seated so that the C clip is closer to center of diff, out towards diff so that the c clip will sit further from diff and more inside the axle. I know it’ll be a smidge more difficult to install it but it gives me more confidence that the c clip is doing it’s job. Funny to think about how these c clips are the only damn thing holding the wheel on the truck.
After this, it’s time to put the drums (now cleaned) on and see how the shoe adjustments goes.

 

[eightynine4x4]

All right, one of these O rings fell apart when I was installing C clips.
Do we really need these Orings?
Seems like maybe there used as an assurance to keep the C clips perfectly vertical and not wiggling around. They can’t be used for locating the clips since mine had one shaft in one place and the other shaft in the other place and both seemed to not be a problem i guess.
Haven’t looked for replacements yet but will.
Are they needed though?

 

[eightynine4x4]

Decided to delete the orings, cut off the one from other axle shaft.
Looked into it and found that mostly they are a factory aid during axle shaft install. Install is fine without. In fact, the rubber is what made my c clips really fastened on VS others who refer to using a magnet to remove C clips. Mine required some force to remove also made it super difficult to install c clips today. Without the o rings, install was as easy as it gets and the c clips are nestled in fine inside the axle.
Getting the pin back in through the gears was tricky but I figured it out. Just had to keep slightly rotating the gears until it all lined up again.

Only thing left is to seal up the diff and install the front parking brake cable and then adjust rear brakes with the drums on. I think I’ll get some bolts from hardware store to just hold the drums on while messing with brakes. Will also bleed them. Then after that it’s just a matter of putting the wheels on and keeping fingers crossed that it all works.

 

[eightynine4x4]

Now that I’ve sealed it up and put the wheels on the ground, I have a concern that I may have to open it back up..

When I was first checking out the cross pin situation and dabbling with the idea of having to pull out the Z clips to get access to the C clips, before I learned I didn’t need to, I pulled on one of the Z clips once or twice with a small lightweight pair of pliers just to get a sense of how tight they were in there. The top of it budged like maybe 1/32” or 1-16” towards me, absolutely no more than that. Then I tapped it back in with the butt end of the pliers. Then, the next day, I think I tugged on it again but I 100% think it didn’t move, and I didn’t touch any Z clip after that. But I didn’t double check if it had moved by butting it back in as a precaution.
My question is… how much does it matter to the stability of those Z clips “staying in place” does like 1/16” this way or that? If I did sorta tilt one just a very little forward towards me, does it just not matter since they’re going to be a little jiggly in operation anyway? Or, could I have set myself up for disaster if one of them is not 100% flushly smacked in?
I actually think I left it in position. But if I have doubts and if the smallest smidge mounting angle makes it so that the Z clip will then start shimmying itself out and totally wreck my diff, I should raise it up and get in there to knock them both back in to be sure.
The functionality of those Z clips is a little mysterious to me. I don’t get how they manage to stay in place forever while the points of contact are in hyper fast motion for decades of driving, since there’s no real point where they lock in nor do they have a fastener. They’re just kinda rammed in.

 

[eightynine4x4]

I did the big boy thing and undid it all to check. Glad I did becuse one of the Z clips was in fact just a smidge pulled out. Maybe 1/32”. Got it back in flush. Other one was flush already.
I reused the oil becuse it was still clear, and expensive.
Went for a test drive and all seems well. Checked afterward for leaks at wheels and no sign so far. Discovered a small brake fluid leak at the union mounted to the top of the diff. Tried to tighten it down to no avail. Will have to address that next.
There is a huge difference in braking now. Still haven’t done the fronts, but the truck feels vastly safer coming to a stop. I’d be surprised if it was just the front brakes. In fact I know it’s not becuse when I hold down the brakes during park to put in drive or reverse, the truck used to rock like a horse but now it’s less like that.
In a couple weeks I’ll be continuing this thread to start working on the front stuff.

THANK YOU SO MUCH EVERYONE!!

Would be nowhere without ya

 

[don4331]

Glad to hear it all works; I learned a couple things myself, so thank you.

Unfortunately, the front end parts I have are all Dana 35, and they seem to be a little different than the 28 ones. So, I can't provide an "exploded view" for you.