New caliper still sticking? HELP!

[patrickdotryan]

Greetings, I have a "71 F250 Camper with the factory dual piston calipers up front. I have read Robroy and others' great detailed info about rebuilding the front brakes and after a solidly stuck caliper on the left side (due to gunky fluid and old calipers), I decided to replace both calipers and hoses on the front. I bought new/remanufactured calipers and I used new bolts/sliders and was sure to lubricate everything. Before I bled the system I made sure that everything slid freely on the bolts, which it did. Then I bled the system to get all the dirty fluid out of the master cylinder. I ran a whole quart through the system and out all four bleeder valves until it was clean and bubble free, so I know that fluid is getting through the system and there are no blockages. As I put the wheels on late last night I noticed that the new caliper on the opposite side to where I had the original problem (right/passenger) is now clamped hard on to the rotor so it's very hard to turn the tire. I haven't test driven and won't be able to for a few days. My questions to the experts here in the forum:

When I drive it, is the disc likely to "pop" the pistons back in and free it up, maybe it's because it's new?
Is there a valve somewhere else in the system that perhaps is not letting pressure release in that one wheel (all the other wheels rotate freely)
I'm assuming those tiny springs aren't supposed to push the pads off the rotor, they're very weak (even used new ones of those)?

Thanks and I'd really appreciate some help here as the truck essentially has the same problem that took it off the road, except now I've spent countless hours and dollars to move the problem to the other wheel!

Patrick in San Diego

[fordman]

if you bled the old fluid through the new calipers then the gunk probably stayed in the calipers. thats what i am thinking.

[patrickdotryan]

Yikes, you may be right. That sounds like a disassemble and clean of the pistons. I've got good at pulling everything apart, but that will still take me a lot of time as well as some risk of further damaging other stuff and rounding out the brake line unions etc. So, before I do that, are there any other reasons, some kind of valve elsewhere that may be stuck that I'm not familiar with? Working backwards from the front wheels, they both join at a splitter on the subframe and then up to the master cylinder. Is there any type of valve in that or is it just a block with some holes in it?

[fordman]

from the master the lines go to the disc brake distribution block then to the crossmember valve then to each front brake. when bleeding the front brakes yo uhave to also pull the pin out on the crossmember valve to let it release. maybe that is the problem. i had almost forgot about doing that.

[patrickdotryan]

Aha! This I did not know or do. However, reading some other posts I see that pulling the pin is supposed to allow fluid to pass through that proportioning valve. Mine had no problem getting the fluid through to the bleeder valves, however, maybe now too much pressure is built up in that one line, as if I have my foot on the brake? Maybe if I pull the pin the pressure will be miraculously relieved in that wheel. Thanks for the help and I'll get back to everyone in a week or so when I have a chance to take another look (traveling over the next few days). Patrick in San Diego

[68SPECIAL]

Let me know if that worked, i had the same problem with my DPC sticking after i bled the system.

[Racer Z]

from the master the lines go to the disc brake distribution block then to the crossmember valve then to each front brake. when bleeding the front brakes yo uhave to also pull the pin out on the crossmember valve to let it release. maybe that is the problem. i had almost forgot about doing that.

What pin? Are you saying that this part is non-standard compared to other vehicles? (No, I haven't done the brakes on my truck yet, but I need to.)

[fordman]

on the F250 disc brakes system there is a part ont he crossmember. it has a pin in it. it has to be relieved when bleeding the brakes. you do it with a special tool. it can be home made. its a u shaped thing with a small cut in one end of the u shape. it holds the pin out while bleeding. there is a discussion about it and pictures on the site. but i have no idea what search words to use to find the discussion

[patrickdotryan]

Yes, agree with Fordman. The line comes down from the Master Cylinder to the frame/crossmember. At that point it is split by a proportioning valve that is on the back side of the crossmember. That valve splits the hard line into two hard lines to the left and the right sides. I saw, but didn't know at the time, the little pin on the underside of that proportioning valve / splitter. Reading back through other posts (search for "PIN", "BLEED" or "PROPORTIONING") that you need to pull out that pin whilst bleeding. Bend up a piece of 1/2 wide and 2" long heavy tin or sheetmeral into a U and cut a notch for the pin on side and another thin notch that will wedge under the "lip" of that pin and hold it open. All theory of course because I am on vacation many hundreds of miles from my truck, but I'll let the group know how it goes when I get back and pull that pin and start the truck up. Patrick (usually in San Diego, but right now in Idaho)

[patrickdotryan]

UPDATE: to get back to my new, sticking caliper, the problem is now solved:

I tried pulling the pin on the metering valve / proportioning valvle that splits the front brake line into left and right sides. No luck, the caliper was still stuck. I even fired up the truck and drove it around the block and used the brakes. Still stuck. So I put it back on stands and pulled the sticking caliper off. Once I had it on the bench I looked in it to see if there was a bunch of grit, but there was very little to none. I also noticed that the pistons were impossible to push back in, even with my whole body weight. I even tried a block of wood and a hammer. No dice. So my diagnosis? A faulty new caliper with pistons way too tight. O'Reily / Kragen got me a replacement and the new one worked perfectly. The guy at the store said he'd never seen one in his 4 years there, but looks like it can happen.

BTW, when I bled the system after reassembly, I pulled the metering valve pin out with some needle nose and locked a pair of small vice grips on the pin sideways. Everyone talks about a tool for this, but my pin had no ridge on it, so that wouldn't work with mine, but the vice grips worked fine. Everything bled reasonably well, although I feel like there's still some air in the system somewhere. Might have to get my local shop to do that as it's pretty hard to do without a helper. Thanks for all the help.

Patrick in San Diego.

[Racer Z]

Glad you got it fixed.