Gimme a brake!

Back brakes not engaging.
Brake shoes are good and adjustment was fine when they last worked.
The problem I’m having seems to have one symptom that the brake pedal doesn’t depress all the way. I mean, it engages higher than normal and activates the front wheels only. I checked temperatures after some stop and go traffic and the front wheels were noticeably hot while the back drums were cool to the touch.
I replaced the master cylinder as a “try” because it was easy and pretty cheap. No improvement.
If I slam on the brakes at say10-15 miles an hour on gravel, the fronts lock up with no back tire slide.
I’m thinking maybe the ABS pump(?). Maybe brake proportion valve(?).
Sometimes in the past, you could mash on the brake pedal and feel it give way a little. That hasn’t happened lately.
The old taco has been pretty hard on the wallet lately!! I don’t mind throwing some dough at it, I just want to make sure it’s in the right place. Any suggestions?

 

What year is it? Does it have the load sensing proportioning valve?

 

Don't 1st gens have a gizmo (forget the name) on the rear axle that screws up the rear brakes when it fails?

 

2003. Not sure about the load sensing, but there does appear to be some sort of valve on the driver side frame mounted just to the side of the spare tire.Clearwater, if you have a part # for that gizmo, that might be a good place to start.

 

You are using the parking brake to keep the shoes adjusted correct?

Brake adjusters working like they should?

If you have ABS the front brakes should not be locking up if that is working correct.

Is your ABS light on?

 

Uh that some sorta valve thingy has a bleeder screw on it, when you change your brake fluid every 30 thousand miles or three years you bleed the system at ALL 5 locations to include the LSPV. My guess is it’s clogged with shmuts from the system. Remove it (go buy some metric line wrenches) clean it, reinstall it, bleed system. That load sensing proportioning valve is expensive be nice to it.

 

Yes, there is a load sensing proportional valve. You could crack a bleeder and have someone press the brake pedal to see if your theory works then disconnect it and move the lever and do the test again.

 

Sorry if i was not clear, I meant remove the LSPV from the truck (why i mentioned line wrenches) take it apart clean it reinstall it, bleed entire system. I did this about 10 yrs ago to my 99 with same symptoms, i took it apart because of how much they wanted for a new one, there was a lot of crap in there, taught me a valuable lesson about break system maintenance, DOT3 is cheap do it often, still have same LSPV in truck, WAA
R/
Andy

 

To Bivouac- no abs light, back brakes adjusted recently when we did the rear axle seals.
To Oldhmech61-ten4 on the line wrenches. Is the LSPV mounted on the inner rear driver side frame?

 

Yes it will be near/ fwd of spare tire, there will be a horizontal arm about 2ft long that connects to a vertical arm which is connected to the axel, obviously there will be brake lines connected to it as well.
When you dissemble the valve dont go to far, dont remove seals or O-rings just pull it apart and clean with acid brush and fresh brake fluid and get all the gunk out of it. Be gentle putting it back together as not to rip or tear seals, hope all goes well for you.
R/
Andy

 

@wingnutj468
It’s this right here

 

yup thats it, have you ever bled the brake system there? also is your lift higher than 3 inches? your extension bracket for the vertical arm may not be long enough. Before pulling the valve, try bleeding it, if no fluid comes out of bleeder disconnect vertical arm from axel and push it up a few inches tie it off to something if you have to then try bleeding at valve again while the arm is held up.
R/
Andy

 

I’ve never bled it no. I have Deaver J59 leaf packs. They’re only 1.5”