Front Brake's locked up??

[Brad J]

My Front Passenger side Caliper on my scout was completely locked up so I installed AutoZone Reman Calipers up front and now both were completely locked up after bleeding. I had to put truck in 4 wd low to get it to budge. Could a master cylinder cause this? I read online that this could happen if the rod to the MC was too long so I loosened the bolts and pulled the MC away from the firewall but still no change, loosened up the line at the MC but no change then loosened up the line at the Front Pas. side caliper and now both front tires turn. This is on my 70 Scout w/ a 67 (? Manual 4 whl disc brakes) Corvette MC (I've tried 2 already but its been a year since putting this one on. Chevy D44 front (from 77 ??) and an IH D60 rear w/ Caddy calipers and disc brakes. It seems wierd to have the same problem w/ a 2nd set of Calipers. I am using the stock hard lines and new stainless steel braided soft lines made at EVCO. I've been battling the battle coming on 3 years to get the Brakes to work safe enough to drive it after new axles Anyone want a scout? J/K.
Any Ideas

Thanks, Brad J

 

[Milner]

Is there a proportioning valvle in the system? Or a dist block?
Is there pressure in the line holding them locked? or could it be a mechanical binding somewhere?

 

[Brad J]

Is there a proportioning valvle in the system? Or a dist block?
Is there pressure in the line holding them locked? or could it be a mechanical binding somewhere?

Sorry, I knew I left something out. I have a Willwood adjustable proportioning valve but only to the rear. I also have a Hydrolic Brake controller tied into the rear brake line. The front brakes go through an electric line lock that I have not hooked up yet. I don't think anything mechanical binding holding them. I was trying to pry the piston back w/ a large screwdriver w/o any luck until taking the brake line off at the caliper. I hope that and the pictures make sense

 

[jdub]

Having a hard time understanding but feeling your pain. My cj5 locked up the brakes out at 5mile. Good thing I was towing it. loosened the plunger rod and was in business for towing. sorry. Sounds like you should have fabulous braking.

 

[waynehartwig]

Retrace your steps - what caused it? What did you do before the problem exposed itself? That line lock has me curious....

 

[Brad J]

Retrace your steps - what caused it? What did you do before the problem exposed itself? That line lock has me curious....

After replacing the axles and MC the brakes have SUCKED. I've bled and rebled the brakes through gallons of brake fluid over the process of a year and a half. The peddle was firm and would stop about 1/2 way to the floor but no tires would lock up. It was more a coasting to a stop feeling. I figured it was the rear Caddy calipers since everyone says they are a pain all around. Fast forward a year of scout sitting lonely in garage while the Basement got the $ and time dumped into it. About a month ago I took it to a local family run Auto shop to have him look at it and the Front Passenger side caliper starting leaking at the fitting and the scout refused to roll when on an incline like a caliper was locked up (and it required lots of gas and clutch work to get it moving). Got the scout home (on the trailer) finally got around to replacing the front calipers and that is where I'm at now. The Line Lock I have installed has both wires still wrapped up around the Line Lock. I have not ran any wires to it yet.

 

[Brad J]

Having a hard time understanding but feeling your pain. My cj5 locked up the brakes out at 5mile. Good thing I was towing it. loosened the plunger rod and was in business for towing. sorry. Sounds like you should have fabulous braking.

Thanks, I tried the same thing for kicks, kindof hoping that it was the plunger rod. My Brakes work too good

 

[waynehartwig]

So when it's locked up, is there pressure on the fluid side? IE can you crack open the bleeder and have it shoot out then unlock the caliper? If so, it sounds like a MC is bad...

 

[Brad J]

So when it's locked up, is there pressure on the fluid side? IE can you crack open the bleeder and have it shoot out then unlock the caliper? If so, it sounds like a MC is bad...

I think so, I'll re-bleed and check for sure.

Thanks, Brad J

 

[ryan iverson]

brakes

second on the mc being bad

 

[waynehartwig]

I think so, I'll re-bleed and check for sure.

Thanks, Brad J

Not necessarily rebleed... I'm just curious if the reason your caliper is locked up, is if it has full fluid pressure behind it. If it does, then it's your MC (since you don't have a prop valve for the fronts).

edit: or the brake peddle isn't releasing back all the way....try lifting up on it the next time the caliper is locked and see if it frees it up...

 

[jdub]

I replaced my mc on said 52 cj and have been rolling fine since then. In the biking world when calipers sieze up it's cause the push rod has pushed the plunger past the fluid and hits a hydro lock stage. Needs to be rebuilt. If that's the case what Wayne suggested may push all the fluid back to the front of the plunger, I'd bet on it. I just cut the crap and bought a new unit. Been perfect since.

 

[waynehartwig]

I replaced my mc on said 52 cj and have been rolling fine since then. In the biking world when calipers sieze up it's cause the push rod has pushed the plunger past the fluid and hits a hydro lock stage. Needs to be rebuilt. If that's the case what Wayne suggested may push all the fluid back to the front of the plunger, I'd bet on it. I just cut the crap and bought a new unit. Been perfect since.

I only suggested that for a test - not a fix!! ...Just to be clear.... When it comes to brakes, I don't mess around with quick fixes....

 

[jdub]

I was afraid that was how it would sound... Sorry. I just meant it to get yourself out of a bind if you were around the block stuck and your neighbors were looking at you funny.

 

[thefirstzukman]

you replaced your brake hoses with braided lines correct? Did you ever squeeze the lines with pliers or anything to stop the bleeding when you changes your caliper? If you did you may have crushed the hose or broke the inside rubber causing a check valve effect.

start at the calipers and work back to the mc. pump the brakes untiil the tires wont move and then loosen them at each joint towards the mc until you find the problem.

 

[waynehartwig]

I was afraid that was how it would sound... Sorry. I just meant it to get yourself out of a bind if you were around the block stuck and your neighbors were looking at you funny.

I knew what you meant, I just didn't want anyone else thinking otherwise - that it would be a good fix type of thing.

 

[gijohn40]

from the sounds of it you said that you let the fluid out of the caliper and the wheels unlocked... to me that tells me that the line lock is not allowing the fluid back to the MC.. I know you have the wires disconnected to the line loc but there are a few out there that when the power to it disappears it locks up... which could be your problem... try wiring the line loc up and see if your problem goes away...

 

[xjc]

No brake expert but there are only a few things that can cause brake to over perform. MC not releasing, Line lock stuck, clogged line, or frozen caliper (if I am not mistaken). If you MC isn't stuck I'd be 100 to 1 odds you line lock is sticking closed, take that out and youre in business.

On the other hand I am in no way qualified to discuss brakes but if youre not hung up on taking advise from someone qualified, I'm youre man .

 

[waynehartwig]

I just re read your original post. Take that line lock out, for now at least. Let's see if we can get your brakes to work at all before adding fancy stuff to it...

I'm guessing (obvioulsy more like it) after the master cylinder, you have a t that branches the line off to the two front calipers?

Also, which end of the MC are your fronts hooked to, and which end the rears? I couldn't tell from the pics....

edit: looked at the pics again, and I still say that line lock is your problem. If that line lock isn't allowing the brakes to function, I could see it stopping your peddle from moving. Thus having no brakes. Thus making your brakes suck, since you are only using the fronts. If there is just enough fluid getting past it, I could also see it locking the fronts up. Which makes total sense, because cracking the line at the MC did nothing, but when you did it to the cailper, it worked. Everything keeps coming back to that line lock....

 

[Brad J]

First of all, Thank you for the ideas, BlueZone has been down everyday this week in my neighborhood Since there is a lot to update on questions, I'll start by saying that the front reservoir goes to the rear brakes and the rear goes to a "T" then to both front brakes. I think I damaged my MC from the rod going too far like jdub suggested. I was pumping the brakes w/ too much force/(built up frustrations) when bleeding probably. I have not clamped off the brake hoses like some shops do, I paid too much for them . When I have removed them I lift the end up higher than the MC so they dont leak. I did also pull up on the brake pedal and pulled the MC away from the firewall but the front tires still stayed locked up.

Right now I went out and could turn all 4 tires (I haven't bled them at all yet, like you suggested Wayne) I then pumped the brakes about 5-6 times till pressure was good and now only the rear tires turn. Opened up the bleeder and it sprayed like crazy for longer than I expected. I am now able to turn the front tires just bairly. Pumped brake pedal again 5-6 times and can't turn the front tires again. So I think the Line-Lock is ok due to pressure changes in the line from pedal to caliper I think I need to start looking for a new MC I'm done w/ trying 67 Corvette MC's. I remember reading that one bolted up to the old Scouts and Jeeps from out of a Ford van or car w/ disc brakes but now I cant find which one. I have to keep searching while I have an Internet connection:-\ Or should I just buy a Willwood MC or nice Summit MC w/ the largest bore they have??

Thanks for the ideas, Brad J.