I imagine the item attached to the frame with the brake lines going out from it is some type of proportioning valve…right? But, my real question is…what is that hard line going from the bottom of that valve that gets attached to the rear differential?? I really don't see what purpose it serves!!

Thanks for you help!!

 

As far as i know, that valve controls the pressure of the rear brakes with relation to how high your rear end is in the air. If you are stopping hard and the rear is weightless then you don't want the rear tires to lock up due to the lower weight. This is an 80's way of compensating that. I lifted my rig 7 inches and had to keep messing with it till my rear brakes were just right.

The bottom (flex line) is what gets the fluid to your rear brakes. Without it, how would the fluid get to the drums? Also, i would recommend replacing all those flex lines with steel braided ones, especially if you are going to, or have lifted your truck. The last thing you want is to have all your brake fluid spilling all over because you snapped the line flexing or something.

Hope that helps.

 

That is the Load Sensing Proportioning Valve (LSPV). Just like 1st Gen Crawler said, this valve changes the amount of fluid going to the rear brakes depending on how much load there is in the back of the truck. The hard line moves up and down depending on the amount of load there is in the back.

Hopefully that made sense!

 

Ahhh…that all makes perfect sense now. Thanks!! I will definitely look at installing some steel braided lines.

 

can you just remove the arm that attaches to the differential?

 

I get the impression after doing some reading that no, you ought not just remove it. Could be dangerous under certain braking conditions.

 

You can remove it but you'll want to replace it with a manual proportioning valve. Drum brakes take less psi to lock up than disks. If you're loading and unloading the bed of the truck all the time the LSPV is a great thing to have (if properly adjusted) because it gives the rears more psi when you have the bed losded down and less when empty. If you have a crawler with a lot of flex it becomes a liability and you want to go with a manual control valve like this:
http://www.davezoffroadperformance.c...ion-valve.html#