Puzzled on locked up front brake

[WARDOG]

A couple of weeks ago the right front brake locked up tighter than a tick's ass.
It was driving fine but when I depressed the brake the right disk brake locked up.
I put air in the line and limped it home in the snow.
I bought rebuilt brake calipers and installed them thinking it was a bad piston.
I got everything put back together today with fresh pads. I drove about a hundred feet and depressed the brake and the same thing happened.
I took the wheel off and tapped on it with a mallet in case it was binding up on the guide rods. Something is not allowing the pressure to neutralize after letting off the pedal. All other corners work fine.
It has a D44 front with disks. It happens with or without the vacuum hooked up to the power assist.
All air has been bled properly and nothing unusual happened prior to this problem starting.

Suggestions?

 

[Viperwolf1]

Look for damage to the steel line or flex hose going to that wheel.

 

[broncnaz]

If you have the gm type conversion check or even just make more clearance under the caliper that is sticking. Many times there is not enough clearance and the caliper sticks on the knuckle because it wasnt clearanced quite enough when converted.

 

[Scoop]

Did you remove the front check valve in the MC if you're using a drum/drum MC?

 

[The Mule]

This same thing happened on my 77 F250 and it ended up being a front rubber brake line malfunction. Since it was just the one side I started on that side and worked my way back to the MC.

 

[nutter3]

I think viper nailed it. (As usual)

 

[bronco t]

Mine did this and i did as you... replaced the calipers and pads (needed them anyways), but as it turned out it was the ancient rubber hoses that were leaking like a sieve and probably had created a bubble-check-valve that limited fluid flow in one direction. New stainless flex lines... Problem solved.

 

[JSBX]

If the front rubber brake lines are old it has probably broke down on the inside causing the line to plug up. If you change the brake line and find that is your problem I would change the other side also.

 

[WARDOG]

...-check-valve that limited fluid flow in one direction. New stainless flex lines... Problem solved.

I don't know what the check valve you are referring to. I see what looks like a proportioning valve? Can someone shoot me a pic of what you are referring to?

I have replaced hard lines, flex lines, both calipers, & pads, banjo bolts, guide pins, lubed everything, clearanced knuckle to caliper housing, trimmed casting seams on calipers, clearanced calipers to mounting bracket, and STILL have this problem. WTF?!
When I get everything put back together, it does not lock up right away. I have to apply the brakes about a dozen times until it locks. Funny thing is that I cannot duplicate the lockup while it is on jacks. This is driving me crazy!

 

[BRONCROB]

Found this.It may show the check valve they are talking about.Are you running two prop. valves?

 

[WARDOG]

Found this.It may show the check valve they are talking about.Are you running two prop. valves?

I really don't know. I don't know what the hardware is in Pic #3. Is that just a union or what?
What is greatly puzzling me is that how can the right brake lock up and the left turn if there is only ONE line going to the union in Pic #4????

 

[BRONCROB]

That's a differential pressure valve.Thats all my 67 has,it shuts off fluid to the front or rear if you spring a leak,not sure about removing it for the disc conversion though.You may just have a bad caliper,sticking piston?Sorry I'm puzzled too now.

 

[bigdaddyof4]

More times than not it is the rubber line at the wheel

 

[PaveBronco]

It’s got to be in the caliper area, you've replaced both and clearanced them. There's got to be something binding in the mounting and it takes some load from actual driving to cause the bind. Elongated mounting holes maybe, anti-seize may help pinpoint any binding. I guess it stands to reason that everything is new, but the mount. I did notice you've got two different size lines, so there will be a slight difference in pressure and volume, but I don’t think it’s enough to cause an issue, certainly not locking.

 

[PaveBronco]

No problems when you do the bleeding, fluid flows freely to the right side? if its bound up and you crack a line, is there some pressure there and it all releases?

 

[cldonley]

A remanufactured caliper from a discount parts store is not necessarily a good one, unfortunately. You might try exchanging it before going further. I don't know how many defective parts I've bought from parts stores!

 

[jerry]

+1 for Viper. I've seen brake hoses that look fine from the outside, but deteriorate on the inside causing blockage.

 

[70 Steed]

+1 for Viper. I've seen brake hoses that look fine from the outside, but deteriorate on the inside causing blockage.

In the OP's post above he said he's replaced the rubber line going to the caliper.

 

[01Dudley]

I call brake hose. Seen this too many times!

 

[jerry]

In the OP's post above he said he's replaced the rubber line going to the caliper.

Hey if I missed that I apologize. But, I see that there's no mention of that there now.

I had the same problem happen on a '67 VW Squareback I used had years ago. Driving along, hit the brakes - front wheel locks up, all others are fine. Brake hoses look ok (albeit old) from the outside, but inside deterioration caused the line to become clogged. and not drain.

Two new brake hoses and I was off to the races... At least, as much as you could race in a car with about 75 horsepower. (lol)