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Discussion Starter · #1 · (Edited)
So i've got an 82' Toyota Pickup, once I went to the 60/14 bolt the brakes went to shit basically. I tightened the piss out of the rear drums to make it work "for now"... well it eventually got to the point where the brakes would completely lock or stick. I figured it was time for change..

Fast forward a month, i've since installed disc brakes for the 14 bolt with 3/4 ton Dana 44 calipers. Swapped in a Rockstomper 1 ton master cylinder, new brake line for the rear and now I have complete mush pedal. I've bleed a good half gallon of fluid through the lines so I know there is no air in the line. Nothing is leaking... Rockstomper MC should be pushing more then enough fluid... yet I still have nada.

If I pump the brakes up for a few minutes it starts to get hard and feel "okay" but the second I let off pumping it goes back to mush pedal. I have a good assumption that the brakefluid is rushing back into the Master Cylinder and not holding pressure, why? I dunno.... My fix? I'm thinking about getting the 10 psi Wilwood Residual valves thinking this will hold the pressure in the line once they are pumped up.

What's your opinion?

I've searched and searched and searched some more. I've read about Flow valves, Residual valves, Proportioning Valves, Master Cylinder and Boosters... no luck thus far and i'm kinda getting tired of throwing money at the problem (yea I know.. stupid) but i'm at a lose right now and i'm trying to get ready for a run in a few weeks.

Do you think installing these Residual valves would be a good direction?

Only thing odd that I notice is the "squeeeeak" or sound of air SWOOSH real slow when I compress the pedal downward but that's ALWAYS done it.. with all the different MC's i've tried... If the booster was bad this would just make the pedal harder to compress correct?

Thanks for any helpful input, I gotta get this thing going soon and i'm running out of daylight here... working 10 hr days and then scratching my head after work for another 4-6 hrs is getting old.

:)
 

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a 10 lb pressure may me too much, the mush you speak of is most likely because the rear calipers are pulling the pistons back in, whe you release the brakes. a 2 lb res. valve should hold just enough pressure to make the pads hold on the disks, a 10 might make them drag.
try pinching off the rear brake line , then pump, if the brakes are better, then thats the problem, if its still mush then the master cyl could be damaged. i have seen damaged power boosters apply the brakes, not allow full travel, but most of the time there is just no power assist.


i have done a disk conversion on a d44 rear and had the results you speak of, the 2 lb valve fixed the problem. i did however also install a proportining valve as the rear would lock long befor the front
 

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Discussion Starter · #3 ·
right on, thanks for the info.

yea if I can get ANYTHING to lock right now i'd be happy to be honest.

I spoke with Dave at Poly today and he was pretty much on the same page so the valves should be here tomorrow and i'll give 'em a try.

Thanks for the input!

I will post my results
 

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to check the booster,

with the engine off, pump the brakes till the peddle is hard and hold
then start the engine, if the peddle sinks a little, the booster is working,
if it doesn't, the booster is junk.

to me, it sounds like air is trapped somewhere, but the res. valve might do you right.
 

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Discussion Starter · #5 ·
pump the brakes till the peddle is hard
:confused:

Doesn't happen, I can pump all day long and it will get hard but the second I stop pumping.. all the line pressure drops out and my foot goes completely to the floor.


So...... I'm hearing alot of the same thing with the air in the line. Since bleeding the hell out of the lines doesn't help what is your suggestion for being completely certain that all lines are airless?
 

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you need to bench bleed your master cylinder if you havent already. Check your front calipers and rear cylinders to make sure they are good as well. The same thing you are talking about happened to my friend. He bought a brand new master cylinder and it turned out to be bad. Could be anything.:confused:
 

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Discussion Starter · #7 ·
talked to Scott at Rockstomper. He's going to send me another one tomorrow so I can verify whether or not its actually the MC


Awesome! Big Thanks too Scott, that is damn good customer service right there.
 

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Had the same problem. Make sure you have the bleeders on the calipers on the top of the piston. I had mine upside down and even pressure bleeding wouldn't get the air out.
 

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Had the same problem. Make sure you have the bleeders on the calipers on the top of the piston. I had mine upside down and even pressure bleeding wouldn't get the air out.
True that on everything said here! you have either Air or a slight leak somewhere. Only a 2 psi check valve is needed for disk brake a 10 psi is for drums. I am getting ready to swap out an 8.8 in place of the wonderful golf cart axle the D-35 I'm going to get the Proportioning Valve out of a Grand Cherokee with 4 wheel disk brakes. As it has the check valves for the disk brakes already built in. Proper and full bleeding of the master cylinder is very important. I am just repeteing everything but they are right on the money here.

The master cylinder can be leaking internally.
 

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Discussion Starter · #10 ·
Had the same problem. Make sure you have the bleeders on the calipers on the top of the piston. I had mine upside down and even pressure bleeding wouldn't get the air out.
AH HA!

I do have the bleeder valves facing DOWNWARD but the brakeline coming in is still a little bit lower than the bleeder valve. I'll swap them to each side and see if that makes a difference.


The caliper should be facing twords the back correct? not the front.
 

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the bleeder valve should be the highest point on the caliper as for as the hydraulic part go. i doesnt matter is the line is below the bleeder if the piston chamber is above it, air will still be trapped in there.

here is a good example in billvistas rear disc writeup


Callen
 

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check the fronts too. i had the same problem, and if your brakes werent working well with the drums, that could be your problem. if they are installed backwards on the front the bleeder will be facing almost straight back
 

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i had the EXACT same problem. except that i had the calipers mounted right, but the single piston "3/4" ton (they are the same as the 1/2 ton, per van) require a HUGE fluid volume, and the newer versions from vatozone have the "low drag" seals installed in them so that the piston pulls back away from the rotor, making a 2lb residual valve, one for front and one for rear, a necessity. the other option is a "fast take up" master cylinder, which has a two stage piston set up, the first piston pushes the caliper close to the rotor but doesn't apply any braking force, then the second piston engages and this clamps the caliper.

i think that is not the best option. i put in the residual valve and "viola" brakes.

after this experience, i will NEVER go with "factory" style brake parts again. the willwood stuff is not much more expensive and way worth it.
 

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Discussion Starter · #14 ·
I really hope i'm just a dumbass and mounted these wrong... that would really make my day to just take 20 minutes to swap 'em around and everything work fine.

reguardless the residual valves are ordered and on their way so i'll be installing them "just in case"
 

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the bleeder valve should be the highest point on the caliper as for as the hydraulic part go. i doesnt matter is the line is below the bleeder if the piston chamber is above it, air will still be trapped in there.

here is a good example in billvistas rear disc writeup


Callen
thats your problem your have ford explorer brakes only good for upto 31" tire imo
i have the same thing in the rear of my rig and they dont work good
 

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I really hope i'm just a dumbass and mounted these wrong... that would really make my day to just take 20 minutes to swap 'em around and everything work fine.

reguardless the residual valves are ordered and on their way so i'll be installing them "just in case"
You only need one residual valve on the main line going to the T fitting for the axle.
And the man is right your bleeder has to be at the top of the caliper. you can't get the fluid to float over the air. You can pour liquid into the top of a jar BUT it is still going to fill up from bottom to top.
 

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i have disc all around on my toy. 3/4 ton stuff, it stops better than anything i own even with the 40s. imho you guys using the residual valves have other problems. all my stuff is autozone. i use a 1/2 ton master and an adapter just like the one scott sells. your brakes should feel awesome.

Callen
 

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i have disc all around on my toy. 3/4 ton stuff, it stops better than anything i own even with the 40s. imho you guys using the residual valves have other problems. all my stuff is autozone. i use a 1/2 ton master and an adapter just like the one scott sells. your brakes should feel awesome.

Callen
Well your tow rig does have drum brakes front and rear :flipoff2:
 

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Well your tow rig does have drum brakes front and rear :flipoff2:
shhhhh, they dont need to know that. :grinpimp: soon to be 4 wheel discs with this very same setup.

never the less ive seen many of this same setup work flawlessly without any residual valves, or any other type of check valve in the system, either you have a bad master, bad calipers, or they are installed wrong.

Callen
 
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