Okay, so I have a conundrum. After having a wheel cylinder seize on me the other day, I took the opportunity to replace all 4. Now despite having bled the system 3 times, whilst I can apply the brake, whilst my wife is spinning each wheel in turn and each will stop, I have virtually zero pressure on the pedal. The only thing I did notice is that at times when you get the spurt in the master cylinder, some small bubbles come out as well. Not all the time but occasionally. Some additional info: Car 39 Ford running the standard single circuit frame mounted m/c. Drums all round. Before the issue car was braking fine with good pressure on the pedal. I did remove and re-installed the brake line/brake light switch block at the back of the m/c to fix a leak, but apart from that have not otherwise done anything to the master cylinder. I did force the seized wheel cylinder pistons back in to see if I could free it up. I removed both pipes from the M/C and blocked off the holes and the pedal is solid, which seems to me to say M/C is okay. Anyone got any advice/come across this before?
Most of the wheel cylinders available for old Fords these days have a mis-drilled inlet hole. The place the hole enters the cylinder is on the wrong side of the rubber cup if the cups happen to be pushed in too much on assembly. You will have fluid leaking out the cover on the end of the cylinder. The fix for this is to assemble the shoes, springs, and cylinders, trying not to push the cups inward too far. Adjust the shoes out as far as you can before you put any fluid to the system. Fine tune the adjustment after that. I've also found it beneficial sometimes to fill the master with fluid, then walk away for a while. This will sometimes let the bubbles in the chamber find their way up. And, make sure the plunger rod has a 1/16" of slop when the pedal return spring pulls it up to the floorboard. This will ensure you don't have that small hole at the bottom of the master well covered by the plunger.
This has always worked for me on an air bound system. Fill master,slightly crack all 4 bleeders and allow time to gravity bleed as alchemy says. Then close all bleeders when you see a steady dribble from all 4. Fill master ,open all 4 bleeders hold brake pedal down tighten all 4 bleeders,repeat this untill steam is air free on all. Then bleed wheels one at a time starting r/r, l/r, r/f, l/f..
Thanks for the reply. No leaks are apparent, but I will pop all the hubs off and look at that. I've just read some posts on the aftermarket cylinder hole issue! I'm wondering whilst I have the hubs off if I could remove the springs and manually pull the pistons out a bit - I like the idea of setting the eccentrics to max, would that be with hubs on or off? The only bit I don't really follow is that surely backing them off again could lead to the hole being re-covered by the rubber cup. I'll check the rod as not sure whether it has any gap or not.
I think you could adjust the side cams all the way out, then assemble the parts, then adjust them in a little at a time until you can fit the drums over. If wheel cylinders still came with those internal springs, we probably wouldn't have this problem.
Thanks for the reply, however, my M/C is mounted on the frame and sits lower than the wheel cylinders. Wish it was higher as I've have definitely tried the gravity method.
There have been a bunch of wheel cylinders on the market with incorrect rubber cups causing major brake bleeding issues. A stock 39 type system with known good components is as easy as pie to bleed. Maybe someone can chime in on bad wheel cylinder updates.https://www.fordbarn.com/forum/showthread.php?t=325805&highlight=Bad+wheel+cylinders
That thread makes very sad reading. So, in effect I've just spend a few hundred Pounds for some C#'#'#'#se junk! I just started looking at the seized cylinder to see if I can refurbish it, think I possibly may be able to as just one piston is binding. Cups seem okay.
Before you give up jack the front of the car up where the master cylinder is above the rear wheel cylinders and gravity bleed. Do the same for the front. You may have to block the jack a couple of times and be sure to use jackstands.
For bleeding , I have several different shop tools & methods to do brake bleeding , One of the best for a One person bleed with master in Floor is Clear Large mouth wash bottle , clear hose , fill bottle up inch or two , stick hose on bleeder other end submerged in brake fluid & pump brakes until no bubbles ,,, you can allso pump brakes from under car with hand so you can see bubbles in bottle
Thanks for the suggestions. Tried a few and still no luck, however I think my master cylinder was maybe marginal as it appeared to give up the ghost today. Now waiting for a new one before I try again. Hopefully come the weekend I can get this bled up.
I was a brake and front end man for years and never heard mention of "gravity bleeding" until amature hacks claimed it works on the HAMB, sorry gents but that is amature hack stuff. The cups not in the right place or just not right in the replacement cylinders and or the hold drilled in the wrong spot seem to be real issues. No springs in the cylinder to keep the cups against the pistons when there is no pressure. on the line. Still outside of a mechanical issue the main thing I have seen with people having trouble bleeding brakes is how they go about bleeding brakes, 1. You have to have the shoes on all four wheels adjusted correctly at the start, 2. you never let the master cylinder go dry. 3. all bleeder screws are closed tight unless you are opening them with the helper holding the pedal down. 4. when you bleed the brakes you start at the furterest cylinder line wise from the master cylinder, you then have your helper SLOWLY!!! pump the pedal and hold it. (They are not allowed to let off the pedal until you tell them after you close the bleeder). You open the bleeder, let any air or fluid out and close the bleeder and tell them to pump it again. You check the fluid in the master cylinder and fill it often until you figure out how many times you can open a bleeder safely with some left in the MC . Once you have a decent stream of fluid coming out move to the next furtherst cylinder and repeat and move on to the next when you get good fluid out of that one. You may have to go around three or four times but that isn't a big deal, the more air that is out of the system the better you can get the air out of each individual line. My daughter who just turned 44 last month started pumping brakes for me when she was four and still is the best brake bleeding helper that I have had over the past 60 years. I've had too many helpers who wanted to pump the pedal too fast or didn't hold it until I told them to pump it again. You can make yourself a pressure bleeder out of a small garden sprayer pretty easily and inexpensively. The big issue with making one is usually coming up with a cap that you can fit to the master cylinder to connect the hose to. You can get away without the pressure gauge as long as you don't put too much pressure on it 15 lbs being the desired maximum. This is one that a company sells that I am using for show and tell. A 1 gallon or less sprayer, a few feet of clear plastic flex hose and a few fittings, I'd use an airhose quick connect on the end to be able to disconnect from the cap on the master cylinder. Good luck and keep us posted on your progress.
Hate to tell you this; but it can work as long as the master cylinder is above the wheel cylinder/caliper. Last vehicle I did it on was an OT modern pickup. Replaced the front brakes, bled them by gravity and never had to pump the pedal. I learned this while working on aircraft. Have I done it on auto's often? No... most of the time it's been pressure bleeder or the old fashioned pumping routine but it can work and sometimes it's the easiest way to get them done. And I ain't no amateur hack! Been doing this kind of stuff since the mid 60's... 43 years as a professional. Oh, and after all the times of using a pressure pot or yelling UP/Down at the helper, the easiest way I've found to bleed brakes is by using speed-bleeders...
Check the rubber cups are not torn, clean the pistons well, give it a hone and reassemble. I assuming you are using residual valves? I use the speed bleeders as well, saved me a crap ton of time!
Love the speed bleeders! I too have gravity bled when there was no other option and I was alone. Granted, only when replacing a component at the wheel. Do not use if replacing master cyl or ABS pump assembly. Retired 30yrs GM master tech.
^^^^A few post above I also knew of "Gravity Bleeding"approximately 35 years before HAMB existent!!!!
These brakes can be a bitch to remove all the air. First off, did you bench bleed the master cylinder before hooking everything up? If the air is trapped up near the master cylinder, the best way to get that part clear is reverse bleeding. I spent hours trying to get all the air out of some of these systems. Fluid should come out of the release port with no bubbles. Be sure the brake pedal push rod is adjusted properly with the proper free play before contacting the cylinder piston.
We did an experiment at work... did not bench bleed a new master, it just took a ton of time to get it where it was happy and built pressure. After I did the brakes on my Ford, I borrowed a vacuum bleeder from a friend with a shop, made like easier and was almost a 1-man dealie. I worked in one shop that had the Ammco pressure pots, drum brakes were a 1-man bleed operation. Front discs needed a helper to push the pads out.
In the business since 1957, I was never an 'amature'. Immediate entrance to the Apprentice Program, I.G.O.A. I was, an AMATEUR (note sp.) model aircraft engineer in my teens... Brake bleeding has been performed in all the above instances, but ONE QUESTION: There are wheel cylinders with NO inner spring??? I purchased some wheel cylinders from South America in the late '60s that had the cups stuffed in sideways!??! Had inner springs, everything machined O.K., just 'stuffed innards'!
Early Ford brakes with the MC below the wheel cylinders ....... you have to bleed them A LOT...... then when you are about ready to give up, bleed them some more. I use one of the big vacuum bleeders and usually end up sucking a couple of quarts through the system before all of the air gets out.
No I didn't bench bleed the M/C since it was already on I figured it didn't need that, but as said I think the M/C may have been on its last legs. Just waiting on a new one. Yep, aware that the push rod needs free play, so I'll make sure it has some when I install the new M/C. I started with a vacuum pump and then switched over to using the UK version of an Easy Bleed kit simply because the vacuum didn't seem to be getting anywhere (however, now reading comments I may have been premature in thinking that way). Sounds like you have to bleed these a heck of a lot!
I was one of the first gravity bleeding hacks on this post. I started brake work arcing brake shoes.Then continued brake work another 35 -40 years, along the way I obtained several A.S.E. certification and one on brakes. I worked mostly flat rate dealerships,front end shops and garages and owned my own auto repair shop. I found if I was gravity bleeding while completing the job it cut my time getting air out of a system in half the time-
Have you got the car up in the air so the suspension and wheel cylinders are as low as possible, and maybe below the master cylinder?
Okay so an update - I think there were a few issues going on as I also found a shoe that was bad as well. I replaced the rear shoes, and re-adjusted all 4 wheels so the shoes were just rubbing the drums. At that point I pressure bled through the master cylinder and finally got some pressure. I've now been able to drive the car around and it stops (albeit not as good as I would like). One thing I did learn from this, is just how important it is to get the shoes out at their working position. My plan is to drive around for a few more miles and then re-adjust the wheels again. Hopefully, once the new shoes have bedded in I'll see an improvement. Once again, many thanks for the support and suggestions.
Unless you had the shoes arched to fit each drum particularly, you will be surprised how long it takes for them to wear in. I’d go out and give them a little fine adjustment every couple hundred miles for the first couple thousand miles. You will become expert at it in no time.
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