hydraulic brakes

[Jerrybubolz]

I will check how the MC lines up with the push rod and check for total throw on the rod.
Also see if the bell crank can be reversed and if it changes anything.
Will look at pedal travel for 6 1/2 to 1 ratio.
Also check to see how much, if any, flex in MC mounting and bellcrank area.
I’ve had all the drums off several times. The brake shoes “look” new with no rust and little brake dust and signs of oil, grease or brake fluid spotting. The linings were glazed in spots. As mentioned I did re-curve the surface of the linings to get a better match to the drums. Scuffed entire areas of linings. Used volumes of brake clean to clean linings and drums. I have adjusted all brakes several times with no change. Got them to the point where the wheels would only turn with very firm rotation while on jack stands. They got warm after driving a couple of miles!
Thanks to jseery and others for posting the pics of the backing plate and bellcrank.
Hope to report back to all of you tomorrow morning after inspection.
Many thanks to all who contributed.
Jerry

 

[JSeery]

To answer some questions on what the original brake systems looked like, the 37 brakes were mechanical brakes using cables. Pressing the pedal down pulled a rod that connected to a center bracket which operated all four cables. When Ford switched to hydraulic brakes pressing the pedal pushed a rod directly connected to the master cylinder (the third image is passenger and 4 & 5 are truck). May be a little difficult to see, but the master cylinder bolts to the same bracket that the pedals are mounted on.

 

[JSeery]

This is a bit of a guess, but looks like the setup you have may be from pieces from the COE brakes.

 

[cas3]

i just did this earlier this winter for my 34. it seems that my bell crank is about the same size as the op's 37. to get to this, i figured the full stroke of the pedal to match a full stroke of the master. by driving a nail in a piece of wood and measuring the stroke at various locations when i pivoted the wood, it came up to about 2" (on center) on the pedal end, and about 1.3 on the master, which going by the photo, looks close to the 37 here. car is not on the road yet, so no bragging rights. is there a better way to figure this? not trying to steal the thread, but heres a pic of mine. grease able bushings, supported on both ends.

 

[Jerrybubolz]

I adjusted the slop out of the rods to the MC and the brake pedal. Now with a LOT of leg pressure, I can lock up the wheels on dry pavement. Still does not perform up to my expectations. Previous owners installed the hydraulic system. Time to get new soft linings, cut the drums and get the curvature of both matched.
Thanks to all who have contributed. Much appreciated.
Jerry Bubolz

 

[JSeery]

Now with a LOT of leg pressure, I can lock up the wheels on dry pavement. Still does not perform up to my expectations. Jerry Bubolz

That's what I was assuming from the setup. There is not enough leverage from the pedal, which leads to increased leg pressure to get the required wheel cylinder pressure. A smaller diameter master cylinder bore would increase pressure, but it would also increase the pedal stroke.

 

[Jerrybubolz]

Jerry:
There is a new 1” bore MC on the ‘37 now. This was added months ago.

 

[Rusty Karz]

That's what I was assuming from the setup. There is not enough leverage from the pedal, which leads to increased leg pressure to get the required wheel cylinder pressure. A smaller diameter master cylinder bore would increase pressure, but it would also increase the pedal stroke.

There is d definite formula regarding M/C size and the wheel cylinders. I put an incorrect one on an MG TD and got a very hard pedal and very little stopping power. A correct M/C corrected the problem. Unfortunately I don't remember the formula as it was years ago. Might be worth looking into.

 

[Jerrybubolz]

My only reference to MC and wheel cylinder bores is from the Dennis Carpenter
Ford Restoration catalog. Here’s what is on my car.

MC 1” bore (Carpenter catalog says MC rebuild kit is 1”)
Front wheel cylinders 1 1/4” bore. (Carpenter catalog says 1 3/8”)
Rear wheel cylinders 1 1/8” bore. (Carpenter catalog says 1 1/8”)

What bores would be the most correct for ‘42-‘48’ brakes? Does the
1/8” inch difference for the wheel cylinders on the front axle make a
difference?
Jerry

 

[flatheadmurre]

Isn´t the std master cylinder 1 1/16" ??
And front 1 3/8"-1"
Smaller master should give you less pressure on the pedal for same system pressure...but at the same time your smaller diameter wheel cylinders are working against you.
As it´s set up now you have less braking power on the ffront axle then as designed from start.

 

[Jerrybubolz]

Isn´t the std master cylinder 1 1/16" ??
And front 1 3/8"-1"
Smaller master should give you less pressure on the pedal for same system pressure...but at the same time your smaller diameter wheel cylinders are working against you.
As it´s set up now you have less braking power on the ffront axle then as designed from start.

The specs I quoted were from the Carpenter catalog. They seem very knowledgeable people.
In a perfect world, what would be the optimum specs for the MC and for front and rear axle wheel cylinders?
Thanks, Jerry

 

[JSeery]

Does the 1/8” inch difference for the wheel cylinders on the front axle make a difference? Jerry

What makes the difference is the surface are of the pistons. Might help you to look at some articles on brake mechanics.

http://www.bullbrakes.com/Technical_Knowledge/Basic-Hydraulic-Theory-For-Vehicle-Brake-System.html

http://www.peterverdone.com/archive/files/hydraulic system theory.pdf

There may be way better articles, these are just from a quick search. There are whole books on the subject!