Load Sensing Valve [Braking]

[kramttocs]

Curiosity got the better of me last night (along with the angst of seeing a part that wasn't powder coated).

The PO had told me he had the rear brakes worked on shortly before selling. A quick look showed that the load sensing valve was just bypassed which didn't surprise me as most of the ones around here I see are a chunk of rust.

I figure if I am going to put it back on, it needs to be checked out and see if it can be refurbished.

So:

First and foremost, use heat on the bracket to valve bolts. Being a west coast truck I haven't had any trouble with removing bolts, even the exhaust came apart without any effort. On this thing I snapped the first bolt clean off. The second bolt I used heat on and while it was pretty stiff, it came out easy enough. Fortunately the snapped off bolt came out of the back of the valve enough that I could grind a slot in it and using heat and a flathead, get it out. I just used a propane torch but due to the plastic parts, I'd do this after the internal part disassembly.

The rest of it was just trial and error until it came apart.

First remove the spring loaded but

Remove the shuttle. I used needle nose pliers and it was a bear to get out. This left teeth marks that I don't think will be an issue but I need to inspect further. I figured I'd tear something up the first time

Remove the spring in the same hole. I had to work it out with the right angle pick as it was pretty content where it was.

Remove the oring under the spring

Remove the clip holding the plastic disc

Remove the assembly (thread rod, the metal disc attached to it, and the plastic disc) together. To do this I used the nut to hold the assembly in a hole in my workbench and then pried up with two pry bars on either side. A puller should be made to do it correctly but it was 4am at this point so pry bars were appealing and luckily worked just fine.

Not much else to it.

The metal disc part has different surfaces on it that push the shuttle out or let it in depending on the rotation.

Even if it doesn't get put back on the truck, it's nice to see what it's made up of.

 

[Gary Lewis]

Scott - You are having too much fun! But up at 4 AM doing it?

So, you rebuilt it but don't know if you are going to use it? How does your truck stop w/o it? You'll remember that I removed the one on Big Blue, so I'm curious.

[salans7]

Scott - You are having too much fun! But up at 4 AM doing it?

So, you rebuilt it but don't know if you are going to use it? How does your truck stop w/o it? You'll remember that I removed the one on Big Blue, so I'm curious.

Good work on getting yours apart, I had the same issues with a broken bolt and struggling to take it apart so I gave up on mine and tossed it in favor of a traditional constant feed.

[kramttocs]

Scott - You are having too much fun! But up at 4 AM doing it?

So, you rebuilt it but don't know if you are going to use it? How does your truck stop w/o it? You'll remember that I removed the one on Big Blue, so I'm curious.

The truck stops like I'd expect although I've never had a non bypassed load sensing valve so I don't have a great comparison.

This truck has the stock suspension (I recall you removing yours as it might not be accurate for BB's air bags) so it would be good to get it installed and see if there is any noticeable difference.

I got to cleaning and organizing the shop so before I knew it I was working Jim's hours.

I also tore apart a HD Distribution Valve that I need to post some photos in a new thread for. 'HD' for lack of a better identifier that I'll explain in that thread.

For this lsv I am first going to see how well it cleans up and coats. It isn't exactly smooth in the plunger (I guess that's a better term then shuttle) shaft right now.

I will have to be pretty confident in it before I go messing with what I know works safely right now.

[kramttocs]

Good work on getting yours apart, I had the same issues with a broken bolt and struggling to take it apart so I gave up on mine and tossed it in favor of a traditional constant feed.

Good to know I am not alone. That thing didn't budge. As long as it was hot the bolt would turn like molasses but steady. As soon as it cooled it locked up again.

 

[salans7]

Good to know I am not alone. That thing didn't budge. As long as it was hot the bolt would turn like molasses but steady. As soon as it cooled it locked up again.

If I remember correctly, the same bolt that snapped on you is the one that snapped on me. I think the other one came out okay, but definitely was a struggle getting it out.

[kramttocs]

If I remember correctly, the same bolt that snapped on you is the one that snapped on me. I think the other one came out okay, but definitely was a struggle getting it out.

Must have used the cheap ones in that hole

I'd read somewhere at sometime that there were different valves based on gvwr.

So for posterity, this is from a 1986 F250 4wd Supercab 460/C6 Long bed 8800gvwr

The plunger is green and on the head of the nut it looks like:

Y. 6 over 13. 252

[Gary Lewis]

If I remember correctly, the same bolt that snapped on you is the one that snapped on me. I think the other one came out okay, but definitely was a struggle getting it out.

I think I got all of them out successfully on Big Blue. But I didn't take it off because of the upcoming changes as much as I was sure it wasn't working. I'd pulled my trailer w/o the brakes on it hooked up and it almost pushed me through an intersection with the front tires protesting and the rear tires making no noise at all. Given that and the plans for the air bags it seemed obvious it needed to come off.

So I'm really glad to see that your truck stops correctly w/o it, Scott.