02 Tacoma load proportioning valve

Edit- added pics below .

Anyone got a source for a new one for my 2002? Toyota want close to $400 with tax for the part. Part # 4791035320 (edited to add this).

Can they be rebuilt?

Mine is crusted in rust proofing, so likely not rusted, but what goes wrong with them?

Thanks,
Don

 

This one?

http://www.toyotaonlineparts.com/to...t/hydraulic-system-scat/?part_name=valve-assy

 

Make it this one for the 4x4.

http://www.toyotaonlineparts.com/to...ystem-scat/?part_name=pressure-metering-valve

 

That's the one.

Don

 

Better than your dealer and it's OEM from Dallas Toyota.

 

ditch it and go manual: Wilwood 260-12627

 

I got a used one from a fellow member. My old one was non functional, somewhat rusty on the outside. When I opened it up one of the internal arms (inside the rubber boot) was rusted to a nub and broken in half.

 

What do the LSPV's look like on the inside? Here are pics of mine.



Looks like a lever on left and right, as load is added, the long rod gets pushed up, changing the position of the lever on the left at the bottom of the load proportioning valve, which must change the flow to the rear brakes.



So I guess those rubbers at the ends of the long rod are only there to protect the rod from dirt and rust. The rod seems solid, I'll reove the ends and see if it is just jammed up with rust which keeps it from moving.



Any insight greatly appreciated.

Don

 

Hoping not to have to order a part.

Don

 

unbolt the lower right side and see if it moves up and down, move it vertically up simulating a load in the bed. if it moves then it is probably fine. if not then it's stuck

 

Disconnected it by removing the 2 bolts (came out very easy) on the right hand bracket at the bottom. The rod moved freely up and down (as did the right end bracket with the rubber over it), took it for a drive (with the rod wired up), rear wheels do not lock up at all, on gravel or pavement. Emergency brake locks up rears fine, so pads are good and rear brakes are good. I had the drums off about 5000 km's ago, lots of wear left on the brake shoes.

The LSV bleeds easily, but no bleeding at either of the rear wheels, pedal stays hard, no fluid at all at the bleeder. Maybe take the LSV apart next and clean it out?

Don

 

Any thoughts from anyone who has had one of these apart?

Thanks,
Don

 

I haven't had one apart, so I can't help you with that.

Are you saying that the back brakes work, but only from the e-brake? When you try to bleed them you get no fluid?

But, the truck stops when you press on the brake pedal, so you assume the master cylinder and front brake calipers are good, yea?

If all that is correct, I'd keep working toward the center. Disconnect the brake line just before the proportioning valve and step on the brake. Fluid? Disconnect just after it and step on the pedal. Disconnect just in before the drums and step on the pedal. Have you done all that and confirmed where fluid movement stops?

 

Looking again at your pictures, not everything I said may be appropriate for the Tacoma. The pictures in my head must be mixed between my truck and my son's 4Runner.

At any rate, I'd try a little harder to bookend the problem. I would pull the brake lines from the drums and try again. And I'd continue to pull lines as many places up and down stream until I was 100% certain of which part or line was causing trouble.

If you've done that and you're sure it's the proportioning valve it seems that your next course of action is pretty clear, even if not one you want.

 

I am getting fluid out of the bleed screw on the LPV, but no fluid at the wheels from the bleed screws.

Front brakes work great, emergency brakes work great. I'll loosen the line coming out of the LPV on the front, if no fluid there, the problem has to be inside the valve.

Thanks,
Don

 

Or the drums, right? Two failures are less likely than one (both drums failing is less likely than the lpv), but still possible.

 

Those things...are troublesome.
I've been following to see the turnout.
I just removed the entire sensing rod today, rubber boot and all. The button the rod pushes is of course, frozen in place.
Wondering if it was hitting the drums at all, I placed the truck on stands and started it up.
With the wheels turning, the brakes will stop the tires with the clutch in. But in gear, foot firm on the brake pedal, I can let the clutch out, engine goes under load but still easily turns the wheels.
The E-brake however, holds much firmer, it won't stall the engine but you can hear it (the engine) go into even more of a load.

I think I'm going the route Jberry went and replace it ( mechanical proportioning valve) with a manual proportioning valve.
But first, I may try direct plumbing, delete the existing valve and cap off the return line. Just to see what happens. Prolly not a good idea, but still curious. My old Scout had a similar valve, I removed it and did direct plumbing and it worked fine.

 

Problem is, we have a safety inspection around here and the manual valve would not pass, nor would a complete delete. I guess this valve improves braking when the truck has no load, old trucks never had anything different than a car. New trucks have ABS, I guess on the bright side, this setup is way cheaper than an ABS problem.

I'll get some pics when I take this more apart.

Don

 

So been busy with other things and when driving the Tacoma this morning, the valve started working. I hadn't touched it yet, but I could feel the pedal was different immediately. Took it out on a gravel road, it locks up every time on the rear.

Don