40 Ford Juice brake performance

L

Lon Jackson

Member
I recently purchased a 1936 Ford pickup that has the 1940 juice brakes installed. The previous owner said that he recently had the brakes redone(new linings, drums turned, new pressure restrictor valves). The system is said to have a mustang master cylinder with pressure restrictor valves for both the front and back.

The brakes don't work as good as I think they should, however, I am not sure what I should expect from this setup.

Should I be able to lock up wheels at slow speed with full application?
Should front brakes engage before the rears?

I have adjusted the shoes with the wear adjustment, I have not adjusted the centering mechanism, I have bled the rear brakes once with some improvement, I have checked the master cylinder fluid level, and there are not any leaks.
 
Yes you should be able to lock up the brakes. I would look at the diameter of the master cylinder piston as well as the leverage between the pedal and the master cylinder. I just use the original early Ford master cylinder and am not knowledgeable about restrictor valves. They were not originally designed to lock up the front first. Photos might help.

Charlie Stephens
 
Assuming Lockheed brakes, the new shoes could be the issue. The shoes need to be fitted to the drums or you are only connecting a small part of the shoe.
 
What JSeery is talking about is called Arcing the the brake shoes. New shoes have oversize linings on them. When you arc the shoes, you measure the drums and then mount the shoes in the shoe arcing machine. It has a micrometer dial and runs the shoe against a grinder, to get the same radius as the drum.

If the shoe it's not "arced" it has a small contact patch on the drum. It will eventually wear in, over time but, still should be able to lock the front tires if, you use enough petal pressure. Lockheed brakes are worse than Bendix brakes, in that regard. Both shoes are "energized" on Bendix brakes and wear more evenly.

Frank
 
Fronts will not lock up either. Supposedly the shoes were arced prior to the installation.
What master cylinder bore should I be looking for?
 
Centering the shoes in the drum is very important. If they weren't centered correctly when installed, performing this operation will improve the braking.
 
Best thing you could do is get a pair of bendix brakes for the front. At least the fronts would stop you.
 
There was also a problem with the NEW drake brake shoes not being the right shape.
Either old relined stock or get original ford shoes and have them relined.
 
If you added your general location to your profile someone might be able to recommend a shop that can arc shoes. They are getting harder to find.

Charlie Stephens
 
Having done several of these over the past 60 years or so. If you use everything off the 40. You should have no troble locking everything up with no problem. Yes the shews have to fit the drums, but that's not the problem. Get the right NC and get rid of thepresure thinga ma bob. I think that waz used for the disk brakes???
 
The disk brake MC, will be biased to the front so, it should still work the front brakes, that's why my question.

If hooked up backward, it should lock the rears.

Do I remember a cam adjustment for the shoe anchors (been a long time since I worked on Lockheeds)? If so, that might be it.

Frank
 
mrtexas said:
Best thing you could do is get a pair of bendix brakes for the front. At least the fronts would stop you.
Click to expand...

Strongly Agree! That's what I did on my 40 wagon. I had the opposite problem. My old juice brakes dragged too tight even when backed off. Yes they were supposedly matched, etc Bendix brakes are great.
 
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what size bore is the M/Cyl ? they could of installed undersized linings. The brake system should be biased by the wheel cylinders as its a single circuit system. Yes they should lock up.
There are a lot more things to consider when putting a dual circuit system on something that wasn't designed for it. Thinking they will just simply work or its a 'safety' thing will lead you down the wrong path.
 
I'm experencing the no lock up issue on my '41PU. Not knowing what was done to my truck before it was stored 30 years ago I went through and checked and adjusted the brakes and still aren't able to lock them up. The drums and shoes look fine. I cleaned everything and reassembled. I have considered going with the bendix system on the front. I have a strong pedal,. Could I have a weak MC?
Randy
 
randy993 said:
I'm experencing the no lock up issue on my '41PU. Not knowing what was done to my truck before it was stored 30 years ago I went through and checked and adjusted the brakes and still aren't able to lock them up. The drums and shoes look fine. I cleaned everything and reassembled. I have considered going with the bendix system on the front. I have a strong pedal,. Could I have a weak MC?
Randy
Click to expand...
Do you have the original master cylinder?

Charlie Stephens
 
It's the original style, but it's been changed. Not sure what to do. They work just not great and do not lock up. It looks like the shoes have good contact to the drums and are adjusted correcty.
 
MC's can't be "weak", unless they are leaking (petal goes down when holding it steady) or there is air in the system (spongy). They only supply hydraulic pressure to the wheel cyl. You can increase the pressure to the shoes by decreasing the size of the MC or increasing the size of the wheel cyl or both. i.e 3/4 MC, 1 1/4 wheel cyl.

If done that way, you will have more petal travel and more pressure.

Frank
 
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