Issue with new drums

[bobslaven]

FORDification,
Info: 1970 Highboy. All drums, boosted brakes.
Story: Pretty uncool wobble on the brakes above about 15 mph. I think (well, I was told by a "pro") that my drums up front were out of round so I replaced them. Replaced the shoes and cylinders and hardware while I was at it. Now I can't seem to get the pedal to firm up. Well, a couple of my bleeding attempts got it to stiffen (in a manner of speaking), but as soon as I fired up the coolest truck in the world and press the brake it goes to the floor with zero resistance. When Billy Bob puts puts vacuum on my bleeders, 1 of the 4 (one which I replaced the other day) doesn't hold the suction.
Plan: Seems like that cylinder that won't hold vacuum is leaking. I'm going to take that drum back off and inspect the cylinder.
Questions:
1. I haven't tried driving it since my work, because I'm under the impression that I don't have brakes right meow...although I've read on the interwebs that they may actually work (or work some). Any truth to that rumor?
2. If the suspect cylinder looks good, could it just be the bleeder screw? Could that leak enough to make my brakes pretty much inoperative? Seems like a fairly aggressive vacuum leak. I estimate 7 seconds from 15 psi to zero.
3. Can I replace bleeders without making a huge mess, or do I need to take the cylinder back off the plate to do that? Seems like I could just screw out the old one and screw in a new one real quick like. With some rags and such handy.
4. Oh, almost forgot. My rookie bleeding attempts were poorly done. I suspect I ran the secondary reservoir dry in the master cylinder. If true, could the air I may have introduced into the master cylinder be enough to cause total lack of brake pedal resistance when the booster's working?
Any tips are much appreciated!

Harrumph!
Billy Bob

[1972hiboy]

Billy Bob,
Put the vacuum bleeder down and stand back for a sec.
I am going to assume you have everything put together under the drums correctly for the time being to address your up front problem which is hydraulic in nature.

step one here is have all four corners been adjusted? I am assuming you have to turn the star wheel adjuster most of the way in to get the new shoes on. You need to go around every corner and make sure your shoe to drum adjustment is fairly correct, if its not and the shoes are to far away form the drum, its going to take alot of brake fluid displaced in the wheel cylinder to make up the distance.

Second is bleeding procedure. I wouldn't use the vacuum bleeder, I have one, i tried it many times and never felt comfortable it was doing 100%. Get a second person to depress the pedal in the cab for you. Start at the wheel farthest from the master cylinder so right rear wheel, bleed until solid fluid comes out, then go to left rear wheel and repeat. when left rear is solid fluid, crack right rear a couple more times again to be sure.

Then proceed to the front, starting with right front then left front.

Check the master cylinder often, running a reservoir dry during the bleeding process introduces air into the system and you need to start all over again.

Do these two steps thoroughly and post back here what results you get.

[sparky72]

Any air in the lines will become immediately apparent when the booster is working, but if you think you might have drained the MC I would take it out and bench bleed it before you do anything else.

Out-of-adjustment drum brakes will also cause a low pedal, so I would check all four corner for proper adjustment (slight drag between the shoes and drums). However, since you say the pedal goes to the floor and never firms up, either your brakes are really far out of adjustment, or you have a good bit of air in the lines and/or MC.

Agree with Rich regarding the hand pump bleeders - they have cost me more time and trouble than they have saved me.

[bobslaven]

Fellas,
Thanks for the quick response. FORDification is awesome because of guys like you.
I bled my brakes 4 times. Only the 2nd time did I try the vacuum and I discovered what y'all said...not a big fan of that technique. I'll never do it again, but testing vacuum at the cylinder seemed like a smart move at the time. I think I used completely sound bleeding technique on the final two attempts.
I figger Rich's (1972hiboy) step one is my real problem. The new shoes (in the front) are not adjusted correctly (probably not even close). From the shop manual, I understood to put on the drums and adjust 'em out until they won't turn...then back it off 10-12 clicks. Unfortunately, I didn't do that for two reasons: 1) I couldn't figure out how to make adjustments with the drums on (the hub blocks that little adjustment window) and 2). Some internet research gave me the impression that could be a little excessive. Added up, those 2 factors convinced me to do it wrongly. Obviously, after reading your responses, I need to figure out how to do what the shop manual says first. However, the only way I've been able to make adjustments is with the drum off. Unless I get some pro tips from y'all, I'm going to go back and keep taking off the drum, adjusting, and putting back on until I have trouble getting it on there. Seems like potential way to scrape up drums or pads or something though.
Reckon I'll be bench bleeding that master cylinder as well. Have either one of you tried the syringe technique while the master is still in the truck?
How about those bleeder screws? Should I be able to replace them without removal? I hope to replace that one on the front passenger side regardless.
I'll report back with some results no later than Saturday. Gotta get my truck on the road!
Thanks again.

Billy Bob

[1972hiboy]

Billy bob, good info,
we are talking about a f250 4x4 right? just be sure. You should be able to get all four corners to adjust the brakes with the drums on with a brake spoon. I dunno about going all the way to the drum stops turning then back off a few until those brakes have broken in a bit. I would just adjust until you get moderate drag on all four. Your going to have to drive a little then re-adjust quite a bit until those brakes break in.
you should be able to replace a bleeder screw while on the truck.
getting your brakes initially adjusted and getting all the air out of the system is your foundation for advancing to other concerns.

Bench bleeding the master is text book procedure. You might get lucky and get it to recover quickly on the truck. in the past i have used fitting the screwed into the master with hose barbs and ran tubes back into the reservoirs to bleed then on the truck that way too.

[bobslaven]

That beast is, indeed an F-250 4x4.

I don't have a brake spoon, trying to use a screwdriver and the hub is blocking me. I'll try bending something or buying one of those fancy tools.

The bleeder screws are also tough to get to due to the hubs. At least up front. Everything in the back is real easy to get to, thank goodness.

Copy "moderate" drag and multiple future adjustments. I was under the impression that would be a one-time gig and the self-adjusters did their magic after that.

I'll report back with findings.

[1972hiboy]

This is the brake spoon i use that i've had forever, snapon b1461.

The adjusters when working perfectly do "motivate" the star wheels but I never count on them 100%. They also only adjust when traversing backwards then giving a firm brake application. so several trips backwards and firmly applying the brake should get something out of them, but if there is any doubt, get in there and do them manually to be sure.

[sparky72]

Fellas,
Thanks for the quick response. FORDification is awesome because of guys like you.
I bled my brakes 4 times. Only the 2nd time did I try the vacuum and I discovered what y'all said...not a big fan of that technique. I'll never do it again, but testing vacuum at the cylinder seemed like a smart move at the time. I think I used completely sound bleeding technique on the final two attempts.
I figger Rich's (1972hiboy) step one is my real problem. The new shoes (in the front) are not adjusted correctly (probably not even close). From the shop manual, I understood to put on the drums and adjust 'em out until they won't turn...then back it off 10-12 clicks. Unfortunately, I didn't do that for two reasons: 1) I couldn't figure out how to make adjustments with the drums on (the hub blocks that little adjustment window) and 2). Some internet research gave me the impression that could be a little excessive. Added up, those 2 factors convinced me to do it wrongly. Obviously, after reading your responses, I need to figure out how to do what the shop manual says first. However, the only way I've been able to make adjustments is with the drum off. Unless I get some pro tips from y'all, I'm going to go back and keep taking off the drum, adjusting, and putting back on until I have trouble getting it on there. Seems like potential way to scrape up drums or pads or something though.
Reckon I'll be bench bleeding that master cylinder as well. Have either one of you tried the syringe technique while the master is still in the truck?
How about those bleeder screws? Should I be able to replace them without removal? I hope to replace that one on the front passenger side regardless.
I'll report back with some results no later than Saturday. Gotta get my truck on the road!
Thanks again.

Billy Bob

I have used the syringe with the rubber nose that presses up against the MC outlet ports, though only on a bench. It worked quite well. Just go really slow on the syringe plunger or you will get a big stream of brake fluid shooting up out of the reservoir. If you have the space you certainly could do it on the truck, but be aware that you are going to get drips and quite a few of them, so be ready for that.

[bobslaven]

Brake Pros,
Billy Bob adjusted the brakes. I judged moderate resistance as still being able to turn the drum with one hand - two hands not required. That's MUCH tighter than before. Then I bled the master cylinder. Used the syringe technique. I think I found some air in the secondary side and didn't make nearly as big a mess as I thought I would. Then I bled the brakes again (after I replaced my bleeder valves). Kind of tricky on one cylinder, but I think that was because the tube on the bleeder wasn't on tight. Eventually no bubbles anywhere. Then I fired it up and drove it around the block. Made a couple good stops in reverse. Put the coolest truck in the world back in the garage. I think it's fixed, but a couple follow up questions.
The pedal is firm and seems to hold (or does it give a little after I hold it in place for 10 seconds or so?), but it engages significantly lower than before. Seems like an excessive amount of free travel - maybe 1/3 of the way to the floor. Also, I kind of figured I'd have some burning shoe smells but got nothing of the sort. Of course I never got over about 15 and just went around the neighborhood (1/2 mile). From my interpretation of the shop manual, I don't believe the pedal is adjustable (and it doesn't look that way to me). Do you think maybe I need to adjust them out a bit? The old shoes, which really weren't very worn at all, had about 3/4 of an inch of thread showing on the adjusters, but I've only got about 3/8ths at this time. That'd make it engage higher, right?
Oh, I've got to center up that pressure differential switch, too. Doesn't sound like it'll be too awful. Will try that today since my brake operator is off work.
Thanks to you guys I'm almost at daily driver status.

Billy Bob

[1972hiboy]

That definitely sounds like your heading in the right direction.
The firm but lower pedal is not surprising, Your gonna need to go for a ten mile drive or until the pedal starts to sink lower, but stop and go traffic, something to get the brakes working. As they break in and burn off the first few thousands of shoe material your gonna have to drive for a bit then re-adjust, you can try going in reverse and see if that changes the pedal but most likely you will need to get the truck off the ground and do it manually. the full break-in process could last for up to 30-100 miles to properly seat everything and get everything burned together and adjusted correctly.

[bobslaven]

Understood. I'll try all that.

How about the pressure differential valve? As I read the shop manual, centering that is something I do after bleeding (if required). However, I've read somewhere in these forums that I need to bleed the brakes after centering it. Might make sense - seems like I could bring air in those lines when I crack 'em. What say you? Should I bleed the brakes again after centering that switch, or maybe only if it's acting wonky?

Thanks again for your patient help. As a reward, I'm going to try to include a picture of the Roach Coach VII. No, I didn't paint it that color. The hottest woman alive likes it, but I'm eventually going to paint it red.

[image]1462[/image]

[1972hiboy]

From what I understand is if there is a pressure differential in the system like say you loose pressure in the rear system the pressure differential will cause the check ball ( or whatever is in there) in the switch to move to one side completing the circuit that illuminates the brake warning light on the dash over the parking brake handle. So if your brake light isn't constantly on then it may still be in the neutral position. I have not needed to reset this valve before so hopefully somebody who knows about the specifics of this can chime in and correct anything I have said that's incorrect or half truth. BTW sharp looking truck.

[sparky72]

The thing about bleeding the brakes again after centering the pin inside the valve is that you stand a good chance of pushing the pin off-center again, since the process itself of bleeding the brakes mimicks exactly the type of brake failure that the valve is designed to detect. IMO the best way to do this is to center the pin inside the valve body, then install a lock tool (like this: https://www.musclecarresearch.com/brake-valve-tool) in place of the electrical switch. These are designed to hold the pin in the centered position while you bleed the rest of the system. Once everything is bled to your satisfaction, remove the lock tool and reinstall the switch. It's the least fussy way of doing everything, in my opinion.

[bobslaven]

Right. Makes sense. Sad thing is, I believe I've got one of those locking tools and just didn't think to use it before I did all of that brake work. Next time for sure. Then again, the brake lamp was on steady before I started this project. I unplugged it before I started bleeding and such though. Hopefully when I fire that beast up it's not on now. Sounds like bleeding will often center it up. Should be able to investigate this evening.

Lesson: before doing brake maintenance which will likely require bleeding, center up pressure differential valve and install the locking tool.

[bobslaven]

Wow. Went out to try to center up my brake pressure differential valve last night. Couldn't have gone much worse. Ended up breaking off the plastic threads of the switch in the valve. Thought I'd ruined the threads trying to remove the debris...but I believe I've saved it. Plastic pieces inside though, so I've ordered a Muscle Car Research kit to take it apart and put it back together again.

Pressure differential valve questions:
1. I see this is a common problem, but any leads on where to buy one? West Coast Classic has one for the Cougar that looks right and the price isn't too crazy - of course the bracket's all wrong. eBay's got a few, but they're crazy expensive. Some dude out East just sold his last NOS one.

2. I only have one wire plugged in my brake pressure warning switch mounted up on the valve - the one that goes to the brake warning lamp. My missing wire is apparently supposed to go to the ignition. Mine isn't there, but the brake warning lamp should still go off if the valve and switch are functioning properly and the piston inside the valve is centered up...right?

Some other stuff went wrong too, but I'm trying to stay pseudo on-topic. At least in the brake zone.