dbbowen

ok so for starters: 1987 4runner 22re new rotors pads and shoes. no leaks in any lines or at the brakes or MC or LSPV.

So ive bled my MC, LR,RR,RF,LF, LSPV a few times now. I have adjusted my LSPV to where the rod is as far out as it will go without being taken out of the housing, and I have added a 4 inch lifting bracket to the adjustment thing on the axle for the LSPV.

Why is my pedal so spongy?! My MC looks to be in good shape, no rust, and theres not a leak inside by the pedal.

Some key things ive noticed:

-In reverse my pedal is perfect, nice and beefy and stopps the truck well. No sponge action
- I tried the reverse and yank the ebrake adjustment thing. It made my pedal stiffen for about 5-10 min then when I pressed the brakes, it sounded like a clung and I could hear the return spring on the pedal, and it went back to mushy. I dont know if these are related to each other but this is what happened.
-truck has "6inches" of lift, but stock springs are flat so i put a 4 inch bracket on the LSPV adjuster.
-sometimes when I bleed the brakes, I barely get any flow out of the rear drums.

Ive been bleeding the brakes with the engine off.

With the motor off and a few pumps the pedal stiffens up, turn on the motor and it sinks to the floor.
When the motor is on, if you pump the breaks it does not build up pressure.


Is this a faulty MC? or are my rear brakes ( or LSPV ) out of adjustment? It is driving me insane!

scope103

If you can pump up the brakes (engine off) and it stays put with a good deal of pressure, then it is probably not the MC. (turning on the motor just activates the brake booster, which gives additional pressure. The pedal should sink a little, NOT to the floor. So make sure your engine-off test has a reasonable amount of pressure on the pedal.) On the other hand, if you cannot pump up the brakes with engine-on, that does sound like a leaky master cylinder.

I'm wondering if you have a problem in the rear brakes, so they are going out of adjustment. Then, each time you apply the brakes you have to pump enough fluid into the rear brake cylinders to engage them; this might feel "spongy." Take a look at this part of the Manual: http://web.archive.org/web/201203161...9-2wdleadi.pdf

dbbowen

Thanks for the reply,

When I pump the brakes with the engine off, it builds up quite a bit of pressure, they get rock solid and are impossible to press to the floor. When I turn the motor on its like all that pressure disappears and the pedal sinks all the way to the floor! I thought since I couldnt pump the brakes and build pressure with the motor on it was my MC too, but since i can build up pressure with the motor off it seems like my MC is working fine?

Im looking at your attachment now

dbbowen

Maybe one of my adjusters are off or something? I just had a replace my shoes and inspect my rear brakes while it was there for other work.

91bluerunner

Recheck that the rear shoes are correct. I've seen this issue before where the brakes feel good in reverse, but not in neutral. I've found that once in a while someone installs the rear brakes wrong (wrong shoe in wrong spot as in rear shoe in front or both rears on one side).

Kean

....since you mentioned this, I did some quick searching and discovered a similar experience:

http://community.cartalk.com/t/brake...ase-help/72703

dbbowen

So for this guy his drums seemed to be out of adjustment. Ill try that tonight

dbbowen

Ill check this tonight too. Are there markings on the shoes that indicate front or rear? I have only changed the caliper pads up front myself, these shoes i have never personally messed with.

Kean

yeah... I wouldn't think that would be the issue with a sinking pedal but apparently it was in his case. I just thought I would share since you brought it up as a possibility and you are at your wits end. Probably one of the easier things to check if you are narrowing down possibilities and it won't cost anything. I hope your problem is simply that. ....good luck.

wyoming9

iTrader: (1)

I see this all the time people look at the rear Brakes and it scares them because it looks so complex most throw the drums back on and never touch the rear brakes .

The brakes are a complete system

Have you even looked at the rear shoes measured your drums .

Ever replaced the rubber hoses ??

I have seen all the hardware replaced still poor pedal old rubber hoses tend to blow up like a balloon even saw it with brand new Chinese hoses

It is the use of the parking brake that keeps the rear shoes adjusted

Not getting fluid out of the rear dirt in the bleeder valves crushed brake line

wallytoo

iTrader: (1)

sounds similar to too much clearance for the rear shoes. first pump gets contact with the drum (barely), second pump creates braking action. you may still have air in the line, no matter how much bleeding you've done, and it should be RR, LR, RF, LF in that order for bleeding.

even though they are different, working on my cj with 4 drum brakes for 10 years gave me plenty of practice adjusting drum brakes.

i agree on the use of the parking brake, too. i use it every time i park the vehicle, so it stays in adjustment (as do the brakes).

91bluerunner

The shoe with less meat on it (shorter side) goes towards the front... If they are different.

boostaddctn

Hi, wondering, has your brake pedal always done this or was it after you replaced something? aight peace

boostaddctn

Any updates? I've been having the same problems as you have described and so far I've changed out the master cylinder and still the same results... I am thinking the wheel cylinders next? lmk and good luck

jaysson_2012

LSPV. They are junk once they get old IMO. I fought a spongy pedal for 6 years before someone suggested I remove the LSPV and replace with a manual valve. As soon as I did I had a hard pedal and way better brakes!

dbbowen

holy crap sorry guys, I went on vacation and was busy getting caught up with work.... Heres an update...

So I went in and readjusted the rear shoes until they had friction on wheel turn. Tried to adjust the Ebrake and broke a screw for where the ebrake attaches to the bellcrank, then I broke the bolt that the ebrake equalizer sits on. I ordered new parts and jerry rigged it up for now, and the new parts actually arrived today so I will be installing them...

So now....

it seems almost like when my engine is cold or something, ill have no brake pedal, then randomly after driving some, i have a super stiff brake pedal and everything is perfect. Then sometimes with a stiff pedal, I get a grinding noise as im coming to a complete stop. I am going insane!!!!!


also, when the motor is off, if i push hard on the brakes ( brakes are always stiff when the engine is off) ill get a sound coming out of what i think is the LSPV, it sounds like when you hone a kitchen knife on the little baton looking thing that comes with the knife set.

dbbowen

So another update.... Replaced the drum bell crank adjuster bolts and the equallizer bolts, adjusted the ebrake and the bell crank adjusters.

So heres what happens with my brakes:

Sometimes, I press the brake pedal, it makes a light clunk, and dropps a little bit before hitting resistance and applying brakes. (no noise from brakes)

Then the other times, the pedal is stiff as it should be and stops very well. However, when I get to about 10 mph and slowing to a stop there is a grinding noise its not a constant grinding noise though, more like grind stop grind stop grind stop.. it does this as i come to a halt.


Then other times (about 5% of the time) brakes work fine as they should. Anyone got any ideas?

boostaddctn

Any updates? I am hella curious on what the problem was/could be?

dbbowen

Yeah so heres my next update....

I first unbolted my LSPV Arm and zip tied it to the top of undercarrage, I got great brakes but my rear brakes locked up quite a bit. Drove it like this for a few days.

Then I took a angle grinder to the arm and cut it and did the 4crawler adjustable turnbuckle method to attach it up and adjusted it so my rear brakes no loonger locked up.

Immediately my pedal went soft again, so I took apart the drums and adjusted them AGAIN and this time I adjusted them so they had some pretty good pressure on the wheel turning instead of just being able to hear them.

This gave me a stiff pedal again about 80% of the time. The other 10% of the time I get a kinda weak spongy pedal and 10% of the time on initial start up, I have almost zero pedal.

Now that my rears and fronts are both working and the fronts are working more than the rears, I am getting this weird grinding noise coming out of the front brakes that I have never heard before. Its odd because I just had new rotors and pads installed on the fronts a couple of months ago and they did not make this noise until now.

Im seriously thinking about taking the axles off with brakes and melting them down into a projectile that I can launch into space

Randyman1967

If I read right you have a lift, if you are still running rubber break lines try putting on braided lines, this will stiffen up a mushy peddle. The rubber expands when you hit the breaks, and the braided lines won't give as much.