Brake pedal too low

[carl750]

I am car guy, but not a Ford guy; however I am helping a friend with a 1936 Ford that has been converted to hydraulic brakes. He believes them to be 1939 front and 1946 rear.

He has replaced the master, wheel cylinders, and lining in rear trying to get better brakes. Things seem to be finally starting to work, except the pedal goes almost to the floor.

When I look into the master, I see two holes under the fluid. A large one to the rear (rear bumper side) and a small one to the front (front bumper side).When pushing the pedal, by looking through these holes; I can see a “brass” piston move.Foll0wing is the sequent of events.Is this right?If not what is wrong and how do I correct.

When the pedal is up: The large, rear hole has the forward half of that hole showing brass and the rear half of that hole showing nothing.The small, front hole shows nothing.

Pushing the pedal a little way down: The brass moves forward and the large hole shows nothing.The small hole still shows nothing.

Pushing some more: The large, rear hole is completely filled with brass. The small hole still shows nothing.

Pushing further: The both holes are filled with brass.

Pushing further until pedal finally gets firm: The large hole is still completely filled with brass. The forward half of the small hole is filled with brass and the rear half of the small hole shows nothing.

Can anybody diagnose the problem from this information?

In case it impacts problem ………. The “hand brake” levers attached to the rear shoes and there cables were not installed by previous owner. Current owner would like to obtain all these pieces so we can install them.

[Charlie Stephens]

Did it work before or is this something new ( I am concerned about things like the brake system having the proper leverage)? If it is new what did he change? Is he using a '39-'48 master cylinder? Are the brakes properly adjusted (note there are 4 adjustment points on the pre war and 2 on the post war)? Did he bleed the system? Were the shoes arced when he replaced them? For the hand brake parts check the for sale section (use the search feature) or try Richard Lacy at [email protected] (mail), earlyv8garage.net (web site), (626) 338-2282, (855) 268-0325 or Dennis Cling at clingsaftermarket.com. If you added your general location to your profile maybe someone could suggest a local expert that could help.

Charlie Stephens

[DavidG]

Is he using the original brake pedal and is the car a late '36? If so, those pedals are closer to the floor than the earlier '36s and '35s and have less travel and likely should be replaced with the earlier pedal version (no modifications would be required to switch the pedals).

[john in illinois]

This is also a problem if drums have too much wear. When the shoes are adjusted out the wheel cylinder will not extend far enough and it takes a second pump. Usually the drums are worn out. New drums are the only way to fix this.

John

[carl750]

I can't tell you much history. The brakes were not good when you bought it. He found the wheel cylinders leaked onto lining and just went ahead and replaced the master and cylinders with one he bought from one of the Ford suppliers.

We have adjusted the master push rod and all the shoes as best I understand the instructions I found on this site.

Pumping the brakes does not raise the pedal higher.

To repeat my original question, does the master piston passing the tow holes sound correct so we need to look elsewhere?

[Kurt in NJ]

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Many of the new production overseas made wheel cylinders have the bleeder hole drilled in the wrong place-- some almost 1/2 way down the cylinder

[FlatheadTed]

Since the 36 pedal is a pull system how is the activating mechanism set up ,if the leverage ratio is reduced then you get this problem . If the shoes go out to far then you need to add thicker linings or space the shoe at the cylinder end .Ted

[V12Bill]

You state that pushing the pedal down, the "brass" piston moves forward. In all the Ford brake systems that I have seen, pushing the brake pedal down,pushes the piston back to the rear of the car. I am confused.

[40cpe]

I wish someone could answer your question on the ports opening and closing on your master cylinder. The advice to contact Richard Lacy offered above is solid. He has the correct parts and knowledge to get you on the right track with a proven record.

Since your master develops a firm pedal, I would lean to the pedal ratio, incorrect adjustment, or worn drums as the culprit(s). I hope you get it sorted out and return here and let us know the solution. It is possible that the real cause has not been offered here and your solution could help the next person with a problem.

[Charlie Stephens]

How about some pictures of how the master cylinder was mounted and the linkage? I have found that sometimes you can put a cell phone camera into locations a normal camera will not fit.

Charlie Stephens

[bbrocksr]

Originally Posted by carl750

I am car guy, but not a Ford guy; however I am helping a friend with a 1936 Ford that has been converted to hydraulic brakes. He believes them to be 1939 front and 1946 rear.

He has replaced the master, wheel cylinders, and lining in rear trying to get better brakes. Things seem to be finally starting to work, except the pedal goes almost to the floor.

When I look into the master, I see two holes under the fluid. A large one to the rear (rear bumper side) and a small one to the front (front bumper side).When pushing the pedal, by looking through these holes; I can see a “brass” piston move.Foll0wing is the sequent of events.Is this right?If not what is wrong and how do I correct.

When the pedal is up: The large, rear hole has the forward half of that hole showing brass and the rear half of that hole showing nothing.The small, front hole shows nothing.

Pushing the pedal a little way down: The brass moves forward and the large hole shows nothing.The small hole still shows nothing.

Pushing some more: The large, rear hole is completely filled with brass. The small hole still shows nothing.

Pushing further: The both holes are filled with brass.

Pushing further until pedal finally gets firm: The large hole is still completely filled with brass. The forward half of the small hole is filled with brass and the rear half of the small hole shows nothing.

Can anybody diagnose the problem from this information?

In case it impacts problem ………. The “hand brake” levers attached to the rear shoes and there cables were not installed by previous owner. Current owner would like to obtain all these pieces so we can install them.

Forget the small hole, the large hole is where the fluid enters the cylinder bore. When the pedal is retracted the hole must be uncovered so the fluid can flow in. Then when the pedal starts down the piston covers the hole and the fluid is pushed through the lines to the wheel cylinders.
Adjust the pushrod until the piston just uncovers the hole with the pedal fully retracted.
Carefully with glasses on watch the piston movement while pumping the brakes and observe the fluid movement. When the pedal returns fully, fluid will return back through the hole and cause a little ripple movement.
Hope this helps, Bill

[Mike in AZ]

welcome to the 'Barn....hope you can get things figured out so the brakes work correctly.....got more pics? of pedal setup, master cylinder, etc?...would probably help the experts here help you....good luck....Mike

[FlatheadTed]

There may be a chance that he has added F1 parts W/C they look similar ,Ted

[JSeery]

Don't want to expose brake fluid to the air any long than necessary, it will adsorb moisture out of the air. You should be able to feel the free play in the pedal, you don't want more than an inch or so before you get resistance.

[carl750]

Reporting back ............ I think I found the problem. We now have firm pedal about 4" off floor.

Reminder ... this car was converted from mechanical to hydraulic by previous owner. He retained the mechanical versions pedal pivot assembly and placed the hydraulic master with the plunger pin toward the back, which is apparently the opposite of from the factory hydraulic setup. Picture attached.

What I changed was the length of the rod from the pedal to the pivot mechanism. See "View through battery box" picture and matching under the car picture. This rod has a (strange to me) "sliding section". I adjusted the rod so the clevis pin was at the very end of the slide when the return spring has pulled the pedal the fully up position. (I also readjusted all the brake shoes, but don't think that did much).

[40cpe]

Third picture: Does the clevis pin have to travel all the way to the opposite end of the slotted clevis to begin actuating the master cylinder? If so, I don't see how you have any pedal at all. Please pardon me if I'm looking at it backwards.

[carl750]

With my adjustment, it no longer slides .... the return spring holds it against the end when the pedal is up ...... pushing down the pedal forces it even harder against the end. At some point a new rod should be created without the slide, but it appears to work as is. Does anybody know what this slide did when the car had mechanical brakes (just curious)?

[bbrocksr]

Originally Posted by carl750

With my adjustment, it no longer slides .... the return spring holds it against the end when the pedal is up ...... pushing down the pedal forces it even harder against the end. At some point a new rod should be created without the slide, but it appears to work as is. Does anybody know what this slide did when the car had mechanical brakes (just curious)?

It allowed the emergency brake to be applied without pulling the brake pedal down. Bill

[Bob C]

Originally Posted by carl750

With my adjustment, it no longer slides .... the return spring holds it against the end when the pedal is up ...... pushing down the pedal forces it even harder against the end. At some point a new rod should be created without the slide, but it appears to work as is. Does anybody know what this slide did when the car had mechanical brakes (just curious)?

I think it's so the brake pedal does not go down when you use the hand brake.

Bob

[rotorwrench]

There are several ways to mount the master cylinders when converting to hydraulics. On many installations, the master cylinder is mounted behind the brake pedal assembly and the pedal is modified to put the actuator arm on the bottom of the pedal shaft instead of the top. Some pedal assemblies were already set up this way and could be easily installed to replace the OEM set up. These give a rearward throw for a master mounted behind. It generally is set up to give a straight push to the master cylinder as well. The alteration in question is different but it seems to give proper function as long as the clearances with the frame are OK and there is no play in the mechanical part of the system.

If your hydraulics are sorted out and function normally, a person has to look at the shoe to drum contact. These old Lockheed type systems needed the contact to be just right or the braking action suffers. It's difficult to find folks that can ark the shoes to the drums now days since the asbestos scare caused the government to want to shut these operations down. There are still some shops out there that can perform these functions but they may be far from where your location is.