40 Ford Juice brake performance

[Lon Jackson]

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.

[Charlie Stephens]

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

[JSeery]

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.

[frnkeore]

Will the fronts lock up?

[frnkeore]

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

[Lon Jackson]

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Fronts will not lock up either. Supposedly the shoes were arced prior to the installation.
What master cylinder bore should I be looking for?

[40cpe]

Centering the shoes in the drum is very important. If they weren't centered correctly when installed, performing this operation will improve the braking.

[mrtexas]

Best thing you could do is get a pair of bendix brakes for the front. At least the fronts would stop you.

[skidmarks]

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.

[Charlie Stephens]

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

[1931 flamingo]

Are the new linings "hard" or "soft" type??
Paul in CT

[Ol' Ron]

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???

[frnkeore]

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

[philipswanson]

Originally Posted by mrtexas

Best thing you could do is get a pair of bendix brakes for the front. At least the fronts would stop you.

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.

[Talkwrench]

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.

[randy993]

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

[Charlie Stephens]

Originally Posted by randy993

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

Do you have the original master cylinder?

Charlie Stephens

[randy993]

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.

[frnkeore]

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

[skidmarks]

Is the pedal out of adjustment?

[frnkeore]

I haven't done a brake job, on Lockheed brakes, since I was a mechanic in the late '60's but, I was right about the anchor adjustment.

That needs to be done first, before you do the regular brake adjustment, other wise the bottom of the shoe, won't make full (or any) contact with the drum.

This is from my '46 Motors Manual:

[randy993]

I'm not sure if the pedal is adjusted correctly or not. It has about 2" of travel before engaging, then holds solid. I did a seach and couldn't find a procedure for adjusting the pedal.

[randy993]

I went through the brake adjusting procedure last week and everything kind of went back to where i started when it was all said and done. Shoes and drums looked fine, no abnormal wear. Keep in mind that my truck was restored and then stored for 30 years. It was stored in a climate controlled garage and I was amazed at how good it survived. I flushed the brake system out good before driving it any. It looks as though all of the brake components and MC was replaced when it was restored, 30 years ago.

[Mart]

It might improve with driving, as things bed in. Drive, adjust, drive, adjust. Make 'em work.

I used emery cloth inside the drum to (sort of) arc the shoes to the drum when I did the brakes on my 41 pickup. They work pretty well.

I have never tried to lock my brakes up, but I do drive in traffic often and they are good enough to give me a feeling of confidence when using them.

Mart.

[randy993]

I agree Mart. I've only driven it a little around town and never will be hitting the interstate in it. I've spent the last couple of weeks going over the wiring. I had signal issues. I've considered updating to the Bendix style. I feel safe in it on the roads and the speeds that I drive.
I have a clymer manual that went through the adjustment procedure and then discribing how they should be able to lock up all four wheels.
Just saying. I didn't mean to hijack the thread, but it was relative to my situation. Thanks for the suggestions.

[40 Deluxe]

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The elephant In the room hasn't been addressed. That is, will your 'trick of the
week' Mustang master cylinder stop you if you blow a line? On a OEM setup, the pedal will go almost to the floor if a line blows. This normal. Has your pickup been tested to see if it will stop with a front bleeder screw open? With a rear bleeder screw open? Your pedal geometry and travel must be the same as OEM or you have no brakes if a line blows. You will be no better off than if you had a single master. Many conversions fail this test, thus giving only an illusion of safety.
The Mustang master has a smaller piston than the original, so you're always going to push harder than with the original.

[JSeery]

"The Mustang master has a smaller piston than the original, so you're always going to push harder than with the original."

Other way around on that one, the larger the piston diameter the more leg pressure required for the same line pressure.

[skidmarks]

You said it's been in storage 30 years. How are.the hoses?

[randy993]

All of the hoses look fine. No signs of cracks or dry rot. I'll replace them at some time.

[40 Deluxe]

Originally Posted by JSeery

"The Mustang master has a smaller piston than the original, so you're always going to push harder than with the original."

Other way around on that one, the larger the piston diameter the more leg pressure required for the same line pressure.

You are so right. Major brain fade on that one! I need to remember: "Engage brain before activating fingers!"

[skidmarks]

I had some hoses that looked good but were collapsed on the inside. But most of the time that makes them work more like a checkvalve and the brakes drag or wont release than restrict the flow and hard to stop

[swanwaco32]

I would also check the shoe material for being too hard. FF I think is the best. You should be able to press your thumb nail in the corner of the shoe. I also use white chalk and draw big X,s on the face of the shoes to check the contact surface after driving. You should break in the shoes without hard stops. We use to get a red tag to hang on the mirror for customer warning about hard stops for 500 miles.

[glennpm]

Make sure that the "major adjustment" or " new shoe" adjustment" from the Ford bulletins has been done.

[randy993]

I didn't think about the age of the shoes. I may replace the shoes and turn the drums and replace the hoses and see what I have then. It sounds like that this stock system should perform descent enough for my driving needs. I can spend the money on rebuilding what I have instead of going with the bendix upgrade.

[russcc]

What Skidmaks pointed out is the junk they sell for brake shoes and or shoe linings do not stop. Case in point, Ray Helgers son replaced the brakes shoes on 'a '40 coupe, it would not lock up the brakes, or stop worth a darn. He got some NORS linings from his Dads diminishing stash, put them on. Then he could lock up all 4 wheels, and said it almost put him through the windshield. Buyer beware. The 2nd key point made by Charley NY is the master cylinder is designed to match the wheel cylinders. Use the original '40. Got mine from Advance Auto. Also check with Fred Wilner at SSO.

[randy993]

Yeah I was just thinking of where to get a shoe you can depend on. I've purchased several things from Joes Antique Auto and he has been very helpful. I may get the drums turned and check the hardness of the shoes and see what I have then.

[JSeery]

Getting the drums turned may not be that easy, not everyone can do them. Also, you will need a hub puller to remove the rear drums.

[randy993]

what's special about the drums as far as turning them on a brake lathe?

[Mart]

Why turn them? That's just a load of life taken out of the drums. They only have a finite amount of material, personally I would bed the shoes to the drums rather than thin the drums out. It might be interesting to see what the drums are at now. Might be way oversize already.

[19Fordy]

I know this has already been covered but, here's another "How To Adjust 40 Brakes".
Notice the 25 to 35 brake pedal requirement in photo #2. Doing this does make a difference. Use a bathroom scale and a piece of 2 x 4 wedged between the pedal and seat.
Of course, you will put another larger and thinner piece of plywood against the seat so as not to cause damage to seat.

[randy993]

I could see the wear on the shoes and it looked like they were making good contact through out the whole shoe. When I checked them last week it was more of a base line on where I was at. I have had the fronts off before, but I got a puller and was able to get the rears off. Everything looked great. Dry, clean, good seals and so on. This was the first time I went through the adjustment procedure and I believe they were actually pretty close. There was some normal glazing on the drums, but no leaks or grease that would effect the performance. I guess my thought was to take off just enough to give it a new texture and then sand the linings and bed the shoes in from there. It depends on where my drums are now measurement wise. What is the max dia. of the drums?

[1931 flamingo]

If you've got it apart why not change the linings to "softer" ones?? You've already done the hard work.
Paul in CT

[frnkeore]

.060 over is usually considered the max.

[Charlie Stephens]

Originally Posted by randy993

what's special about the drums as far as turning them on a brake lathe?

The drums and hubs are an assembly and require that you turn them as an assembly using a special adapter for the rear. It is been so long that I can't remember for sure about the fronts.

Charlie Stephens

[skidmarks]

If you have the small mandrel like the Drum Doktor (that how its spelled) you can turn the rear drums.

Modern Ammco ect lathes the mandrel too big. But they will fit the fronts.

If the pedal isnt pulsating and the drums are not over sized I would not turn them. Good original drums are getting harder to find

[randy993]

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Thanks Charlie. I understand now.

[cmbrucew]

Are the shoe linings too hard?


Bruce

[19Fordy]

For what it's worth, I remember (years ago) reading in one of the Ford manuals that OEM 1940 ford car brake linings were .18 in. thick. Does anyone else remember?

[frnkeore]

Yes, my reference, says .187 but, the new linings were probably .050 thicker, to allow arcing for oversize drums.

Here is the tool that was used to set the anchor and upper cam adjustments.

Anyone still have one laying around?

Frank

[19Fordy]

That is a very neat tool. Never saw one before. Thanks.

PS: There's one for sale on Ebay $140 buy it now!
https://www.ebay.com/itm/Vintage-K-R...AAAOSw6j1bnEUa

[Sod Buster]

I drive my 47 like it doesn't have brakes, lol.