Deuce Brakes Locked Up

Well if it's not one thing..... Long story short, I limped about a mile home in third gear. The pedal was rock hard on the last stop sign before home. Stupid me, I should have pulled over. When I parked it, smoke came out from the front and the smell of brakes. I crapped my pants.... I inspected all the drums and they were all HOT. I have not looked at it yet because I am ashamed to even think about what happened. I know it's probably the air pack and maybe a pedal adjustment and sure why not, a bleed issue. I do keep the air pack oiled I check everything ALL of the time. Apparently not good enough.

My concern also in this is if I roached my shoes and drums. Any takers? Any advice? Tell me I'm screwed? Maybe some moral support? I have my flack jacket and helmet on, so fire away!

Ok first, I would say you may be ok on the drums, (but don't hold me to that), check them and be sure. I have the same problem with a 51 Ford where the pedal is hard as a rock and the brakes are tight, I found it was the master cylinder. The master cylinder was not releasing the pressure when the pedal was and eventually would lock up the brakes. Take your drums off and check them out, check your shoes, it may just take a deglazing of the shoe.

Your airpac needs to be replaced or rebuilt. When you go over today and start her up, most likely the brakes will be back to normal until you apply them a time or two. The air pack is n not allowing the air to vent when you apply brakes.

If it's not the vent line, then one or more valves in the airpak cylinder are stuck. Just lubing it now may be too late, but it should be done at least on a yearly basis. Small plug on the back, use airtool oil or fine hydraulic fluid...

How long have you had the truck? How many miles have you put on it? Any master cylinder work or brake adjustment work done lately. An improperly adjusted master cylinder pushrod will block the compensating port in the master and over the peried of several stops, apply the brakes. Odds are that if no work has been done it's an airpack issue but if someone was monkeying with that pushrod or changed the master, could be the mentioned port.

Apply the brakes till they wont release again. Then crack open the line coming out of the master cylinder. If the brakes release. it's not the airpack. If they release, then replace or rebuild the master cylinder. Make sure actuating rod on the master is adjusted correctly. If they don't release, crack the line coming out of the airpack. If they release then you have an airpack problem.

Ditto badgmc56's comments. In my case it was the master cylinder.

same problem working on soluttion

I agree wholeheartedly with BADGMC56. I had a similiar problem with my deuce last year. This issue will be aggravated in the heat. I checked all my brakes and unless you literally set them on fire you should be fine.

I initially rebuilt my master cylinder, and the problem reappeared again this year. I cracked the input line to the Air-Pack and the brakles released and you can hear them as they loosen.

I have double and triple checked the brake pedal linkage adjustment to the master and that does not appear to be the problem. I know that the vent for the air pack is hooked directly to the vent for the master. If the outlet for the vents is clogged, when the brakes release, you are venting the air into the master cylinder and essentially pressurizing the brakes WITHOUT pushing the pedal. Now the pressure is not great, but if the cups in the master act as check valves because of the pressure from the resevoir, then the brakes get tighter and tighter, never quite locking up, but not loose enough to roll.

I have to check my vents and I have not had time as of yet today to do so. I plan on actually taking the air vent off the air-pack and blowing air through it with an airline to verify it is open. I am going to remove the small vent line for the master first and check that to see if it is open and plug the tee where it connects to the main vent line before blowing air through. I don't want to push a bunch of junk into my master.

Other history on my truck for comparison, I replaced all the wheel cylinders and have bled the system and it is full of BFS. and is clean. The airpack is lubed and seems to work perfectly and the truck has good brakes, when it is not as hot as it got yesterday in the 95 degree heat.

I will share my findings and I have a confab scheduled with JATONKA to compare notes later as well....

RL

badgmc56 said:

Apply the brakes till they wont release again. Then crack open the line coming out of the master cylinder. If the brakes release. it's not the airpack. If they release, then replace or rebuild the master cylinder. Make sure actuating rod on the master is adjusted correctly. If they don't release, crack the line coming out of the airpack. If they release then you have an airpack problem.

Click to expand...

For dum dums like me, could you further explain which lines on the MC and airpac?

The deuce was built with a "SINGLE CIRCUIT" brake system. In simple english, the brakes have one system where a single piston creates the pressure to operate the brakes. All modern cars have multiple brake systems. The reason is that if you have a failure of a brake line, or caliper or wheel cylinder the separate system will still work and still provide stopping ability.
On the deuce, the master cylinder has one outlet. This brake line exits the rear of the master cylinder (as it is oriented in the truck) and then become the "Input" for the airpack.
The aiurpack outlet heads for a "T" and the brake lines that transmit the hydraulic pressure to the brakes head for the front and rear.
TM9-2320-209-20P is the parts manual for the deuce and has a great illustration of the brake system on page 273. Here is the link in the resources section for this manual:

http://old.steelsoldiers.com/index.php?module=pagesetter&type=file&func=get&tid=1&fid=file&pid=96

I checked my vent lines today and it was no joy as to finding a caouse for my brakes hanging....I hope to confer with the sage JATONKA later today and perhaps John will shed some light on our shared predicament.

RL

rlwm211 said:

The deuce was built with a "SINGLE CIRCUIT" brake system. In simple english, the brakes have one system where a single piston creates the pressure to operate the brakes. All modern cars have multiple brake systems.
RL

Click to expand...

Correction to above- the mid to late 1980's deuces have a "DUAL CIRCUIT" brake system. And of course the M35A3's have dual circuits.

I know it's an air pack problem. That will be handled shortly. The MC is new. I was helping the previous owner replace the MC and the air pack before I bought it.The air pack was off a parts truck. It makes sense with these symptoms that the hydraulic brake light switch would work and not work and the pedal would get hard. Then I'd crack the bleeder on the air pack, the brakes release, then I had a brake light again. So a few things I learned. If the air pack is bad, the hydraulic brake switch will not work properly, the pedal will be hard and will cause the brakes to lock up. Diagnosis: I had a bad air pack to begin with, just took a year to really find out.

I feel a little reassured about the shoes and drums but I'll know when I test drive. For now, it will be replacing the air pack. Then giving a good bleed again. Then if I have more problems, well as it goes, "If it's not one thing, then it's another" and "it's always something" If you ask me if I know about Deuces, I say **** no. But I know a helluva lot more!

Anyone have pictures of the airpack etc . Any PM I can do ?? Thanks

Balloons are air packs in a way, Type in air pack in the search thread. I'm sure pics are in one of the 22 threads.

And by the way, the posts by Cranetruck and Recovery 4x4 have been the "lectures" accompanying my manuals. I learned about oiling the air pack last year from one of Cranetruck's posts

What is the best lube to use when servicing the pac???

Air tool oil is the consensus. There is a plug on the back of the air pack (the old long air pack) that you can squirt some oil into. BUT... you may not be able to free it up. There is no plug on the new style (short). You can disconnect the "J" line on the back of the pack and put some oil in that. I do it every 6 months.

cessnatwin said:

What is the best lube to use when servicing the pac???

Click to expand...

Air tool oil.

To update on the Big Ugly... I replace the airpack with a brand new one. The old airpack was not all crudded up through. I am gonna rebuild it. I gave the brake system a good bleed with a pressure bleeder (Thanks Walt!). The brake pedal is not hard at the top anymore. The brakes engage on the pedal about a third of the way down. I let out the master cylinder adjustment a little bit. I have about 3/4" play in the brake pedal. I believe the specs on the pedal are 1/2" to 3/4", correct me if I am wrong. ***** With that being said, is there a spec on the actual travel of the master cylinder or is measured purely by the pedal play? ****

I tested in the driveway and she stopped like she was supposed to. I took her for a test drive everything functioned just fine. She had more get up and go even before this current incident which leads me to believe the brakes may have been dragging a bit. Also the brake pedal did not get harder the more I drove it, which was a previous symptom. I did not notice any pulsating when i stopped or did any panic braking. Anything else I should be looking for? Any recommendations?

I have new sets of shoes for all 3 axles. I will be replacing those soon enough just for my peace of mind. Especially when I found out how easy it is to take down an axle. My friend had an axle leak and let me help do the work. He explained everything step by step while we did the work. So that myth has been busted.

Good for you Garandfan, glad you got it figured out!! I'll be crawling under the deuce as soon as it stops raining to lube the airpack.

Yeah I tried to lube the new air pack by removing the plug.... Stripped that one out too! I had to lube it through the "J" line.