Front brakes locked up

[dirt_migirt]

I just put new calipers and pads on my truck blead the brakes and went to move it and the front brakes are locked up and won't let the wheels spin so I cracked the bleeder and they released I re blead the brakes and it keeps doing it. It is a 77 c10 with manual brakes the guy before put a 80 an up master cylender on it cod that be the problem???
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[ont_guy_38]

Front hoses might be NFG.

[DetroitIron]

Originally Posted by ont_guy_38

Front hoses might be NFG.

Yep!
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[mgchevyparts]

Probably not hose(s) if both sides do it. Something is keeping pressure to the calipers. Did you make any changes/adjustments to the master?

[Rufton]

+1 everybody and mgchevy; unlikely both hoses would collapse into a check valve at same time.
Could be faulty residual pressure valve(s) or sticking MC piston if not the mentioned hose.

[meatwagon83]

check the prop valve, its rare but i have seen two bad brake hoses before

[wraprail]

Brake hoses? Doubtful
@dirt.....What is the pedal like? Hard? Spongy? Does it travel much?
What about when you bleed them?
Did you bleed the rears too?
If not you should do them in order.
We have to assume the calipers have been rebuilt properly and are in good condition.
Make sure you have the correct pads and caliper hardware.
You should put some white grease on the O rings where the calipers slide and on the spindle where the caliper contacts.
Just some tips. I can't see it being hung up like that due to lack of lube.
I would agree with meat that possibly the metering valve inside the combo valve is stuck. There is a button that you pull to aid in bleeding. Try messing with that button or maybe smacking the valve with a hammer a few times.
There is no residual pressure valve on the front brakes. (there should not be)
Brake hoses don't magically cause brakes to lock up. OK maybe it is possible but I still think it is highly unlikely.
That's about all I can think of.

[ont_guy_38]

It's actually very common for the brake hoses to cause the calipers to stick, They swell on the inside and won't let the fluid back through. Not thinking though, prob not both at once.

[88Jimmy4x4]

how hard was it to get the calipers on the rotor?

maybe you have 1" calipers on 1.25" thick rotors

measure the thickness of your rotors then post the part number of the calipers you bought.


(this is just a wild guess lol)

[motornut]

when you bled the rears did you remove the drum and clean?
or just bleed from the outside?
i'd check and ajust the rears
seized up ajusters ....no rear brakes coming on?
does your ebrake work?

[Rufton]

Originally Posted by wraprail

Brake hoses? Thats a good one. lol
How the hell could faulty brake hoses cause the calipers to stick?
They can't.
@dirt.....What is the pedal like? Hard? Spongy? Does it travel much?
What about when you bleed them?
Did you bleed the rears too?
If not you should do them in order.
We have to assume the calipers have been rebuilt properly and are in good condition.
Make sure you have the correct pads and caliper hardware.
You should put some white grease on the O rings where the calipers slide and on the spindle where the caliper contacts.
Just some tips. I can't see it being hung up like that due to lack of lube.
I would agree with meat that possibly the metering valve inside the combo valve is stuck. There is a button that you pull to aid in bleeding. Try messing with that button or maybe smacking the valve with a hammer a few times.
There is no residual pressure valve on the front brakes. (there should not be)
Brake hoses don't magically cause brakes to lock up. That's Ridiculous
That's about all I can think of.

Tis possible for old hose to act like check valve; ID may be restricted and interior may develop debris and barbs from disintegrating hose.
We don't have to assume calipers were built proper.
I didn't say residual pressure valve was supposed to be installed; My point is to check if defective residual pressure valve is installed.
Not so Ridiculous.

[cmyc5575]

I had an issue not so much with hoses collapsing but the fitting that goes threw the frame from the metal break line to the hose, was rusted and was preventing fluid from going threw it. But most lily not your problems since it sounds like they locked up at the same time.
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[wraprail]

Originally Posted by Rufton

Tis possible for old hose to act like check valve; ID may be restricted and interior may develop debris and barbs from disintegrating hose.
We don't have to assume calipers were built proper.
I didn't say residual pressure valve was supposed to be installed; My point is to check if defective residual pressure valve is installed.
Not so Ridiculous.

I stand corrected...

[Big Port Jimmy 6]

Check the free play on the master cylinder pushrod. Not enough will make the brakes lock up. Pump them until they lock up, then loosen the two mounting bolts on the master, if the brakes release, you do not have enough free play. Jay

[88Jimmy4x4]

how did the brakes work before you touched them?

[dirt_migirt]

they didn't work at all when I bought it all I have done is replace the calipers and his is where I am now

[Pork Chop]

I had an 85 that sat for years and the clips that hold the brake lines to the frame were rusted enough to close off the brake lines. Don't know if that would cause them to lock up
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[Smallz72project]

If this were to come into my shop this is what I would do. So we know that when its locked up and you open the bleeder valve at the caliper that it will release. Need to find the component that is holding pressure. Move up and crack loose the line into the hose, does/doesnt it release, from there to the proportioning valve then to the master and any other components inline. If you open something and it releases continue up, when you find something open and not allowing it to release the bad component is the last component before where you just opened the system. If you get to the mastercylinder and nothing changes...we have to assume that you got bad calipers.

[nascarmikeb]

Originally Posted by Smallz72project

If this were to come into my shop this is what I would do. So we know that when its locked up and you open the bleeder valve at the caliper that it will release. Need to find the component that is holding pressure. Move up and crack loose the line into the hose, does/doesnt it release, from there to the proportioning valve then to the master and any other components inline. If you open something and it releases continue up, when you find something open and not allowing it to release the bad component is the last component before where you just opened the system. If you get to the mastercylinder and nothing changes...we have to assume that you got bad calipers.

On my 87 sierra classic, the driver side is stuck. I switched the caliper and a new brake hose. I have the correct pads and rotor. The truck sat undriven for 3 years. None of the other brakes are locked up. I will try the above method in hopes of finding the component that is not allowing brake pressure to release. The fluid in the master cylinder is murky brown. Im not sure what that is about. Also what is the "correct procedure to bleed all 4 brakes. I have drums in the rear and discs up front.

Mike

[74CustomK20]

My 98 (newer but same issue) had this. My master cylinder went bad n wouldn't release. Went through 2 hoses n 2 calipers before I found out.