What is this? And what is the best way to fix it.

[vzfit]

Members,

I need a little advice. After a wheeling trip to Barnwell Mt., I noticed something hanging down from the rear axle. Obviously, I'm not much of a mechanic (i stick to changing the fluids and rotating the tires). I have 3 pictures I will attach. My questions to you being 1) what part is this and what is its function? 2) How should I go about fixing it?

I have a 1985 Toyota 4runner efi auto. Thanks for any help you can offer.

Respectfully,
Sam

 

[fourwd1]

That is the Load Sensing Proportioning Valve for the brakes.
It senses the amount of weight in the bed and adjusts the amount of brake power to the rear wheels accordingly. The actual valve is the part on the frame. The rod connects to the axle. The angle of the rod varies with the bed weight, the rod works the valve, adjusting fluid flow to the rear.

 

[vzfit]

Thanks

Thanks Fourdw1,

The rod has been ripped from the axle bracket. Do you know how it connects into the rubber piece? Do you recommend replacing the connection or just try to fit it back in? The end of the rod doesn't appear to have been welded or anything.

Thanks,
Sam

 

[DC runner]

LSPV. Drum brake require less pressure than DISC to operate, as a result any vehicle that has a disc/drum combo requires a pressure reduction system to bump down the line pressure. If you don't and you send the same amount of pressure to disc and drum, the drum brakes will lock up.

That valve is a reduction valve. It bumps down the brake line pressure by a set amount, depending on how open or closed the valve is. The valve is attached to the bed frame. The more weight in the back, the more OPEN the valve is allowed to be, since you would need more back brake to stop.

So. You should get it fixed, or say F it. I am not sure what its default mode is... but, I want to say that if the default mode is more closed than open then you are not at a risk of locking up but you are probably not getting much help from the rear brakes to stop. Since most vehicles USE 70% Front and 30% Rear, then this means that in most situations you are ok. Understand though, that unless you fix it; in an emergency stopping situation your truck could be missing up to 30% braking ability


Hope that helps.

 

[Pyroboy]

Like the previous poster said, the more the rear suspension is compressed, the higher the rod moves and the more pressure bias is applied to the rear brakes. When you installed lift springs in the truck, the axle mount for the rod needs to be extended or the rod disconnected. I just supported mine from the body above in a fixed position that mimics a fully loaded stock suspension.

You can google 'LSPV Removal' to see how to remove it but you need to revise the brake line plumbing to make it work.

 

[fourwd1]

Thanks Fourdw1,

The rod has been ripped from the axle bracket. Do you know how it connects into the rubber piece? Do you recommend replacing the connection or just try to fit it back in? The end of the rod doesn't appear to have been welded or anything.

Thanks,
Sam

If it's broken off you might be able to tack weld it back together.
Don't try removing the rod from the valve, you'll end up making things worse.

Or you could just tie it up to the body, that would put it in the position that provides max braking power to the rear wheels.