Bleeding brakes-pedal pressure problem. Could use some advice/suggestions
 

Here is what I have.
Mostly early production '32 frame, steering, etc.
'53-'56 PU front brakes.
'39-'42 rear brakes. ALL the brake components are new except for the drums. They have been turned originals.
Front brakes are adjusted to a slight drag. Rears are not adjusted. (need 25-35 pounds of force applied to brake pedal)
Master cly I think, (bought it too long ago, you know, CRS) is a non power Mustang. Hardly any "free pedal travel")
Brake lines are 1/4" all polished stainless, with double flaired ends and polished brass T's.

Bleeding procedure. Master cly was bench bled by the instructions. Fill, until fludi starts to run out ports, then cap off with the plastic plugs. Short quick strokes until resistance.

Rears first. 5 pedal pumps then hold. Ran 1/2 a bottle of fluid thrugh. Got air bubbles, No hi pressure fluid squirts, just some soild dribble. The pedal would freely go to the floor.

Fronts, the same way. 5-10 sometimes 20, pedal pumps then hold. Got some air bubbles at first, then just some solid dribble fluid. Finished off that quart bottle of fluid.

Pedal would freely go to the floor.

I should ad, that there are NO visible leaks.

If I would pump the pedal fast and hard, I would get about a 1/4 pedal, and it would hold. Let up, pump again one time, pdeal would freely go to the floor.

Pump the pedal fast and hard several times again, get that 1/4 pedal. One could, with much difficulty, turn each wheel by hand.

What procedure am I missing here? Thanks

Re: Bleeding brakes-pedal pressure problem. Could use some advice/suggestions
 

don't know but have you adjusted the cyl so that the piston can come all the way back to pick up more of the fluid ?

Re: Bleeding brakes-pedal pressure problem. Could use some advice/suggestions
 

Sounds like no residual pressure valve.

Re: Bleeding brakes-pedal pressure problem. Could use some advice/suggestions
 

I was a fleet mechanic for 30-years and have bled hundreds if not thousands of brakes. Every once in a while, you get one that's a pain in the butt, it's hard to get the air out of it. I would go ahead and adjust the rears as close as you can, you can go back and finish the rear adjustment once you have the brakes bled. Don't forget that the rear early Ford rear brakes you used have the long shoes towards the front, the opposite of every other drum brake on the planet. Adjust them up tight and then try bleeding the brakes. If it still causing problems, they make a visegrip with smooth edges that is made for clamping off hoses. Clamp off the rear brake hose and see if the pedal comes up, that way you can tell if the air is trapped in the rear or somewhere else. I have plugs for the master cylinder too. I can remove the lines and plug the holes, and the pedal should be rock hard.

When you bleed brakes pump the pedal slowly not fast. Pumping it fast can break the air up into tiny bubbles making it harder to get it out. You want to slowly push the air down the lines and out the cylinders.

Re: Bleeding brakes-pedal pressure problem. Could use some advice/suggestions
 

Adjust the brakes tight; fronts with the star wheel, rears with the two top adjusters. Might be all you need to get a hard pedal; then go back and properly adjust the brakes.

Since you sound a little unsure on the master; maybe pull the boot back and make sure it is a 1" bore.

Re: Bleeding brakes-pedal pressure problem. Could use some advice/suggestions
 

I would check what KurtV said first. You need a small bit of freeplay in the brake pedal so the piston comes all the way back. Also, if the MC sat for years with no fluid in it, perhaps it isn't working correctly.

Re: Bleeding brakes-pedal pressure problem. Could use some advice/suggestions
 

Yes! There is just under a 1/2" free pedal travel.

Re: Bleeding brakes-pedal pressure problem. Could use some advice/suggestions
 

Yes, it is a 1" ID bore.

The reason I am unsure of what vehicle the MC originally goes to is I bought it 3-4 years ago. I was getting a number of items ready for a certain color at the local powder coaters. The MC was one of those items. I pulled the MC "innards" out in order, wrapped them in a brake fluid soaked rag then put that into a sealed plastic sandwich bag, then placed in the back of the cabnet untill I was ready for them here 3-4 weeks ago, when I assembled and installed the MC. After the MC was powder coated, I shoved a rag in the bore and sealed it with one of those plastic tubing plugs, then put the chrome bail and lid on, put all that into a plastic bag, and it went into that same cabnet.

I have run all the brakes up tight, like you sugested waiting for a family member to stop by and help me.

Re: Bleeding brakes-pedal pressure problem. Could use some advice/suggestions
 

I don't see why not it shouldn't be working. I sealed it up good 'n tight in the dark reaches of a cabnet I seldom go into,

Re: Bleeding brakes-pedal pressure problem. Could use some advice/suggestions
 

Soon as I get someone to help me, (son-in-law, and grandson were here on Sat) Might have to wait until next Sat for help.

I will post what my findings are.

This should be a SIMPLE task. A dual port MC, plumed into OEM front drum brakes, and rear drum brakes. That's it.

Re: Bleeding brakes-pedal pressure problem. Could use some advice/suggestions
 

Is the master cylinder a drum/drum unit.Disc/drum masters are different, most do not have a residual pressure valve built in.

Re: Bleeding brakes-pedal pressure problem. Could use some advice/suggestions
 

Does the linkage move the master cylinder piston through its full stroke?
Have the wheel cylinders been examined to see that the bleeder holes were drilled to be at the top of the wheel cylinders?
Have the shoes been fit to the diameter of the drums?
Has the centering of the shoes been checked?—-

Re: Bleeding brakes-pedal pressure problem. Could use some advice/suggestions
 

acchaplin, curious, are using glycol brake fluid or silicone brake fluid ?




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Re: Bleeding brakes-pedal pressure problem. Could use some advice/suggestions
 

Yes, I am pretty sure it's a drum/drum, non power MC. If I remember right, this pictulair MC was reccomended to me. Early '60's Mustang.

Re: Bleeding brakes-pedal pressure problem. Could use some advice/suggestions
 

There is no "linkage",,,,,,,,,,,. Original pedal assembly, with a aftermarket MC relocation(?)/remount kit. Bracket bolted to the original holes in the K-member, allowed a later MC to be mounted.

The only thing I canged was the steel brake rod supplied in the kit. (goes from the bottom of the pedal va a clevis with the rod threaded into it, directly into the MC). Made it out of 304 stainless and added a little 1/4-3/8" to the overall lenght, and half dozen more threads.

There is no one around here that can do that "shoe fit to the drum" thing any more. Place was bought out in the early '90's. Just tell you to "drive aroun the block" several times, or "come down Cheat Mtn on 50 one time." They will be seated in no time.

As far as "centering",,,,, I don't know. The shoes and hardware mounted up only one way. Here is a picture, you can please tell me if you see something not correct. Thanks

Re: Bleeding brakes-pedal pressure problem. Could use some advice/suggestions
 

You have the early rear brakes and did you adjust the bottom anchors? Also you powder coated the MC. Did you powder coat the lid? There is a vent hole in the top, is it clear?

Re: Bleeding brakes-pedal pressure problem. Could use some advice/suggestions
 

First, exactly what Mustang brand and model number did you buy?

As TJ said, make sure the MC air bleed hole is open

Looks like you put chrome acorn nuts on the bottom adjusters which is not correct.
The way to adjust is shown in the attached Ford bulletin.
The bottom studs have flats on them with a punch marks as shown below





https://www.fordbarn.com/forum/attac...3&d=1729622497

Re: Bleeding brakes-pedal pressure problem. Could use some advice/suggestions
 

Just slip hose over the jaws.



https://www.fordbarn.com/forum/attac...8&d=1696960642

Re: Bleeding brakes-pedal pressure problem. Could use some advice/suggestions
 

No. The lid and bail are chromed. Yes the vents are open because the rubber lid gasket/bladder sucks itself down into whichever MC port I happen be bleeding.

Re: Bleeding brakes-pedal pressure problem. Could use some advice/suggestions
 

abc

Re: Bleeding brakes-pedal pressure problem. Could use some advice/suggestions
 

Yes, pics would help.

Re: Bleeding brakes-pedal pressure problem. Could use some advice/suggestions
 

Update; Adjusted the rear barkes by the top adjusters. (no way to do the 25-35 pound of force) Hard to tell the brake drag from the differental drag.

Alsp reduced the free pedal play down to around a 1/4"

Got son-in-law to pump the pedal harder. Used for force that grandson. Got some more air (not very much just a couple of small bubbles) out. Ran a 1/2 quart of fluid through. Also have a 1/4 pedal now! Even after sitting a while. That is a IMPROVEMENT.

But. There is more pressure on each brake now with the pedal applied. It now takes a crowbar (and excessive grunt work. More than what was required to turn Saturdays bleeding, hubs) between the lugs to turn each hub. That won't stop the car!

I has to be the MC, not suppling enough pressure to all 4 brakes.

If I switch MC's. Just in case this MC I have now was bad (wrong) from the beginning. What specific MC would you guys suggest?

Also. What would happen if I do NOT use the 25-35 pounds of pressure procedure on the pedal to adjust the rear brakes? Thanks for the help.

Re: Bleeding brakes-pedal pressure problem. Could use some advice/suggestions
 

Here they are.

Re: Bleeding brakes-pedal pressure problem. Could use some advice/suggestions
 

Not sure on your conversion but some were supplied with a 1" spacer i think. maybe some of your stroke problem

Re: Bleeding brakes-pedal pressure problem. Could use some advice/suggestions
 

Looking at your pictures raised a question; how did you convert the deuce pedal to push on the master cylinder and what pedal ratio did you end up with?

I have noticed when an ear is welded to a '32 pedal long enough to line up with a master cylinder mounted under the K member, some pedal ratio is lost. My kid usually retains the 1-1/16" Ford master as a 1" dual has a low pedal.

Re: Bleeding brakes-pedal pressure problem. Could use some advice/suggestions
 

Early in this thread you said you had 1/4 to a half" inch of free play to the piston, then later you stated its been reduced to 1/4", which is still too much. You only want enough that you know for a fact the piston can travel all the way to the end. Like 1/16 or less.

with the boot off you can feel the rod to see if it has any play, and thats all you want or you have cheated yourself out of some stroke.

Re: Bleeding brakes-pedal pressure problem. Could use some advice/suggestions
 

Oh feces! I flunked ratios in school,,,,,,,,,,. I have absoultey NO idea what it is, how to figgure it out, or what to do with it!

You want a better picture of the lower pedal? I don't see where anything has been welded to the pedals. (confused by your statement)

So, are you suggesting that I get 1 1/16" ID, drum/drum, non power MC?

Thanks

Re: Bleeding brakes-pedal pressure problem. Could use some advice/suggestions
 

OK, thanks. I can use all the help/suggestions that can be throwed at me.

The '39 to '48 Ford brake service manual states to have 1/2"-3/4" of free pdeal travel. I was using that as a guide. I started out with just a whisker under a 1/2" of free travel. Then today reduced it to a 1/4". I can bring it down to a 1/16", or just a little free travel feel.

Re: Bleeding brakes-pedal pressure problem. Could use some advice/suggestions
 

The 1/16" has nothing to do with the pedal. He is asking you if the MC piston comes all the way back.
Pull the rubber boot back and make sure, when the pedal is up, that the piston has returned to the rest position, and has a little clearance. (This is the 1/16" that the other poster is referring to). The MC piston has to come right out to it's stop to allow the fluid in the reservoir to enter the pressure side of the system.
Someone also asked you if you have the residual pressure valves fitted. I haven't read your reply to that.
There are two different residual pressure valves, one for disc brakes and one for drum brakes. The residual pressure valves are usually found by removing the brake line fittings at the MC. You can get after market ones that fit in the brake lines. I think they are important, especially if your MC is close, or lower in height, than the wheel cylinders.

Re: Bleeding brakes-pedal pressure problem. Could use some advice/suggestions
 

It really isn't a good idea to pinch shut brake hoses, as unseen damage can occur. The proper way is to plug the line or port with steel/brass fittings.

Re: Bleeding brakes-pedal pressure problem. Could use some advice/suggestions
 

Your pictures don't show the master cylinder push rod connection to the pedal, but pre-'39 pedals "pulled" cables from the top of the lower pedal, while later hydraulic pedals "pushed" the master cylinder from the bottom. A tab may have been added to the bottom of your early pedal, or a linkage is used to convert "pull" to "push". The pictures don't show this clearly.



The hose running from the secondary master cylinder port should be anchored or supported at the junction to the line, not left floating. I can't see the primary line, but the same would hold true for it.


Actual push rod clearance to the primary master cylinder piston can be very small (.020"-.030") as long as your pedal fully returns with it's own return spring. This will minimize actual pedal "free" movement.


It's very important to be sure the pedal can fully stroke the master cylinder before the pedal bottoms out.

Re: Bleeding brakes-pedal pressure problem. Could use some advice/suggestions
 

After a lot of searching, this is the closest I could find that looks like your MC. https://www.performanceonline.com/19...R-DRUM-BRAKES/


From the searching, it is likely that you don't have residual check valves in your MC. When you rebuilt the MC from your bag of parts, did you have two of these, one for each port?


https://www.fordbarn.com/forum/attac...1&d=1729693218


If you don't remember, push a paper clip it each port. If you feel resistance right away, you have a check valve in that port. check both front and rear.




https://s19526.pcdn.co/wp-content/up...0000016000.jpg


Glenn

Re: Bleeding brakes-pedal pressure problem. Could use some advice/suggestions
 

Regarding an alternate MC, I did a bunch of searching for stepped bore designs, being familiar with MICO products, and ended up with this. It works great. I also have 10psi check valves in both the front and rear brake lines.



https://www.fordbarn.com/forum/showp...98&postcount=5


The whole thread is here,
https://www.fordbarn.com/forum/showt...nder&showall=1


Glenn

Re: Bleeding brakes-pedal pressure problem. Could use some advice/suggestions
 

Your pictured residual check valve is only found in single circuit masters, internally at the bore's end. Dual master residual valves are much smaller and located as you stated behind the tube seats.

Re: Bleeding brakes-pedal pressure problem. Could use some advice/suggestions
 

Good, thanks

Re: Bleeding brakes-pedal pressure problem. Could use some advice/suggestions
 

If you didn't pull the brass seats and remove the residual valves from the master when you had it powder coated; is it possible the heat when it was baked damaged the rubber plungers or the springs?

Re: Bleeding brakes-pedal pressure problem. Could use some advice/suggestions
 

[QUOTE=69a;2345417]The 1/16" has nothing to do with the pedal. He is asking you if the MC piston comes all the way back.
Pull the rubber boot back and make sure, when the pedal is up, that the piston has returned to the rest position, and has a little clearance. (This is the 1/16" that the other poster is referring to). The MC piston has to come right out to it's stop to allow the fluid in the reservoir to enter the pressure side of the system.
Someone also asked you if you have the residual pressure valves fitted. I haven't read your reply to that.
There are two different residual pressure valves, one for disc brakes and one for drum brakes. The residual pressure valves are usually found by removing the brake line fittings at the MC. You can get after market ones that fit in the brake lines. I think they are important, especi

Sorry, I see now that two different subjects are being emphisized.

The "free pedal travel" requirment is stressed in the manual by BOLD print in a couple of places. Since that "free pedal measurment" is emphasized, that is what I thought you guys are/were refering to.

Ok. YES, the MC piston returns to the snap ring by it's own spring resistance every time it is compressed either by hand or the pedal, with the boot off.

I will get grandson to take better pictures of the bottom of the brake pedal assembly this evening. Those pictures I had him take were of just the MC as requested.

The "residual valve" request, again, I quessed I flunked that too. What does it look like? You say they're located inside the MC at the fitting port. The only thing inside those ports is the reversed flair the double flaired line seats into by the flair nut.

That MC is supposed to be a manual drum/drum unit. The outfit that suggested that I use that pictulair MC, told me, that is all I'll need. (no external valves) Funny. I can rmember that statment from years ago, but I can't remember what the MC part # is.

So. I guess that you are going to have to' show'/school me on these residual valves, along with the pedal ratio deal. As I have stated, I have no idea what it looks like, where to find it, and what to do with it. thanks

Re: Bleeding brakes-pedal pressure problem. Could use some advice/suggestions
 

Push a paper clip it each port. If you feel resistance right away, you have a check valve in that port. check both front and rear. If there is no resistance, you need to buy external residual pressure valves.

https://s19526.pcdn.co/wp-content/up...0000016000.jpg


https://www.ebay.com/itm/294911150189

https://i.ebayimg.com/images/g/5t8AA...w2/s-l500.webp

Re: Bleeding brakes-pedal pressure problem. Could use some advice/suggestions
 

That was a bare, empty MC housing when I had it powder coated. I had metal plugs screwed into the tubing ports. The powder coater taped off the bore and the surface where the lid gasket/bladder seals.

Powder coating is a little more resistant to brake fluid lifting than what paint is.

The inside fitting port looks exactly like Glenn's picture!

Re: Bleeding brakes-pedal pressure problem. Could use some advice/suggestions
 

Do ALL those external residual pressure valves look like your picture!? Those big things!?