Rear brakes started locking up while driving around today in my 86 4runner. Made it home and found the passenger side dragging hard. The drivers side looked like a mess inside. PO disconnected the parking brake cables. Said it was because of the LSP & BV. I'm just starting to work on this truck. Any thoughts? Attached photos are of the driver side which wasn't really dragging.

 

Pretty sure that arm on the upper left side that has the twisted wire holding it in place is not correctly installed. The portion of it that reaches out to the right is supposed to make contact with the teeth on the adjuster wheel I'm pretty sure. And these brakes are supposed to be "self" adjusting when you activate the parking brake, so yeah clearly that mechanism has been disabled on purpose by the PO. The FSM might have a good image, but if not, hopefully you can find some good pics.

 

Ya no doubt. It's zip tied on the other side. I was more worried about all the grease and the fiber that's piled up on top. I'm pretty sure the load sensor is way out of whack but I'm not sure about the process of adjusting it. I've read it in the FSM but it seams like it may be beyond my tool sets. Grease from the axel seal?

 

i don't have much input to offer as I'm still working on what began as my brake system and has snowballed into.... anyway, I would just clean it all out real good, connect what's supposed to be connected and go from there. Pics from when I was freeing my outer and inner bell cranks

 

Thanks hurricanes. Looks familiar! I'm wondering if it's possible that a combination of my really bumpy road and the fact that there are virtually no shocks in this thing made the rear end bounce up and down so much it caused the LSV to over pressurize? Basically thinking it was loaded and unloaded with each bump that it just over loaded the brake system. I'm going to do exactly what you said though and start putting it back together and see what's failing. I'm still feeling a little daunted by the FSMs explanation of how to test the LSV BP. Guess I'll cross that bridge when I get to it. The kicker of this whole thing is that I was on my way home from auto zone with parts to fix the suspension, brakes and exhaust so I could go get it smogged tomorrow. Guess that's on the back burner now. Haha!

 

I'd probably start with determining what the lead was before I clean. Like pull the lips of the cylinder back to check for moisture. But whether wheel seal or brake cylinder you need to fix that obv. Your shoes don''t look much warn either. Sadly I don't think you should try to clean those shoes. You really can't get fluids out of the friction surfaces.

Hurricanes Left rear has a good pic of the "self" adjust mech. That baling wire on yours is holding that part that should be on that pivot pin on top of rear-side shoe. Of course that mech wont work well if the park brake cable isn't functioning.

While you're at it ensure those cables move freely. I had to disassemble my driver side and put pbblaster down it and work it for a few days. Should I just spent bux to buy new?
Yeah. Probably.

The spring under/behind adjusting cam is a bug-a-boo. Takes patience and (I had to get help) 4 hands to reassemble. I'd get all that squared away before I started worrying about the diverter valve.
Also the actual shoes are the same across a wide range of years. My 95 shoes are exactly like a 99. (Altho the actuating and park brake assemblys are way different.)
Not mechanical or financial advise.

 

Basically, the LSPV valve adjusts the rear brake pressure according to the weight on the bed of the truck. More weight more rear pressure. Less weight less pressure.

If it were me, I would stick a manual proportioning valve in it, and be done with it. You just don't want the rear brakes locking up. I think the factory manual has the unloaded brake pressure. You will definitely need a brake pressure gauge. And you would be wise not to haul anything at max bed load with a manual proportioning valve.

The LSPV is not cheap. Then you have all the rubber bushings and etc. to buy to do every thing back to factory.

 

Thanks snippets,
I was thinking of doing that. All the threads that I have found on here explaining how to do it are old and the pix are missing. Any suggestions on how to's?

 

Well, I pulled the whole assembly apart today and cleaned everything. Opened the cylinder boot and a ton of brake fluid poured out. I went ahead and put a new cylinder in and will put everything back together in the morning. Also got new shoes to replace the damaged ones. I went ahead and ordered a cheapo aftermarket LSPV just to see if it fixes the issue. I also found a supplier out of England that carries the spring and boots for the whole assembly. As a side note, I replaced the shocks as well and lo and behold, the old one were completely dead! I'm hoping with the new parts and new shocks my rear break lock up issue will subside. Plus, it'll be nice to have ap parking brake again! More to come...

 

Looks a little better. Went ahead and redid the front brakes and calipers while I was at it. Also put in 4 new shocks, replaced transmission, transfer and diff oils and put in a new lspv. I even found i was missing 2 engine mount bolts. No big deal... I'll take it for a test drive in the morning. Fingers crossed! 🤞🏻

 

And you get what you pay for... The crappy after market LSPV I ordered from Amazon was total crap. Leaked right away. So I'm returning it and ordered one from Amayama. I shoulda known better.

 

that’s interesting. Sorry to hear that. I had bought and OEM one for about $100 from UAE, and thought afterwards I could have gotten by with the cheap one. But I also have bought new brake parts that leaked right away (wheel cylinders for a muscle car)

 

So I replaced all 4 brakes (pads, rotors, calipers, shoes, cylinders, etc.) And replaced the LSPV. Got everything bled and went for a test drive. Brakes were spongey to begin with and over the course of 10 minutes driving began to stiffen up. Then they started dragging. Barely made it home. This time it was the front brakes dragging instead of the rear. Did all the leak tests on the booster and it's holding vacuum. Check valve is good. My next step is to pull the booster and master cylinder, check for push rod alignment. If that doesn't work then I'll replace them with the ones from my other 4Runner. Doesn't help that my Dodge is OOS as well... bad truck karma this week. Any suggestions are welcome at this point.

 

Push rod for the booster / Master cylinder was out of adjustment. I didn't have an adjustment tool so I cobbled one together from stuff I had laying around the shop.

Bench bleed on the master cylinder and now all's well in brake land once again. Too bad that led to an electrical rabbit hole that I'm now chasing. But at least I can stop!

 

glad to hear you got the brakes figured out. Finally finished all my lines and bled them yesterday, last step bleeding the LSPV and the bleed screw head broke off At least it seems to have broken after closing the bleed port! Went to start her up and the battery didn't even have one volt!!! So i may have an electrical rabbit hole of my own, we shall see

 

Oh buddy, for your sake I hope the parasitic draw on yours is easier to find than mine. I'll link the post I have going for that. Some folks had some good input and info to help out. Glad to hear you're close to running her!

https://www.yotatech.com/forums/f116...r-draw-317168/