Brake system Work, what to look for?

[Kaiser67M715]

I will be going through my brake system in the coming weeks. I will be looking for insight and advice as I go through the system.(sorry for long post, but want to be thorough)

Truck is a 1952 M35 with Reo OA-331, everything stock except added reverse lights and a 12 volt converter. Brakes were completely gone through and overhauled 5 years ago. I also do a brake drum check every spring, to check wheel cylinders.

A little backstory, end of two weeks ago, I drove my truck into work, no issues, nice firm pedal, full brake fluid reservoir->remote mount on firewall. I drained air-been having problems with moisture, but been really cold mornings, draining tanks at night had significantly less water. Truck then sat the whole day, 6:30am to 5pm. I hop in at the end of the day, fire her up, wait for air pressure to build, and step on the brake...straight to the FLOOR. It did hold the truck on the incline when I released the parking brake, but definitely not safe to drive home. Fluid level was fine.

I got it towed home beginning of last week, ordered a New Master Cylinder and a rebuild kit for an air pack-I had a spare in unknown condition, I was hoping to rebuild, but it was no good->air side was nice and clean, but brake fluid side had some major gunk and a few to many rust pits. Upon getting the truck home, I had 1/3 pedal, same fluid level. sitting all week, today I moved it to its temporary home 1/2 pedal, but fluid was lower to start-after moving it around, fluid was back up.

Right now I plan on looking over the current air-pack and see if I see anything out of the ordinary. Then I will move to the master.

Is there anything I should keep a look out for that may explain the brake issue as is?

 

[montaillou]

I don't know enough about your truck, and I don't know if it's a mistake (or my ignorance to ask), but should you be posting in the Korean War - The Early Deuce forum instead?

 

[gimpyrobb]

Honestly

Id go through the hubs. I swapped all new parts in not 10yrs ago and have had 3 wheel cyls go bad on me. Ive also see the studs the brake shoes float on get loose on other trucks.

 

[rustystud]

I don't know enough about your truck, and I don't know if it's a mistake (or my ignorance to ask), but should you be posting in the Korean War - The Early Deuce forum instead?

The early Deuce section is for the M135 and M211 Deuce. The early M35 deuces are almost identical to the more "modern" M35's with the Multifuel engines. In fact there are a ton of early M35's that where converted from the gas engine to the Multifuel diesel.
You can recognize them by the gauge panel instantly.

 

[Kaiser67M715]

Honestly

Id go through the hubs. I swapped all new parts in not 10yrs ago and have had 3 wheel cyls go bad on me. Ive also see the studs the brake shoes float on get loose on other trucks.

Everything was tight and clean at the beginning of the season (late April) however I do plan on double checking after getting the air pack and master cylinder squared away.



I have a new master cylinder waiting to go in, but it looks like at this time, my whole issue was with the air-pack, brake fluid came out of the small airline(breather line) that comes out of the accumulator(is that the correct term?) when I removed the air-pack from the truck.

Further disassembly showed brake fluid in the rear air cylinder, the pushrod had this grey stuff on it, it appears to be part of the seal. That seems to be the only area of concern, there is some discoloration in the small bore that leads to the accumulator (again, not sure on the correct term) and separates the incoming brake fluid from the air side, but there was no indication of fluid leakage that way... I tried to get a picture of the main fluid bore, but being I misplaced my big wrench, I couldn't remove the end plug. It is surprisingly clean, but does appear to have some dirt/sediment/junk at the end.

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[77 AMG]

You got lucky, it looks like. Man, I wish the airpac on my Deuce was that clean! I had to take a 3lb hammer to the piston rod in the air chamber to get it to start moving, so that I could even start to tear it down. It is junk anyways, from fluid and other stuff sitting in it for who knows how long, from rust. Even after honing it, the pitting is too extreme for me to consider a re-build.

 

[rustystud]

You got lucky, it looks like. Man, I wish the airpac on my Deuce was that clean! I had to take a 3lb hammer to the piston rod in the air chamber to get it to start moving, so that I could even start to tear it down. It is junk anyways, from fluid and other stuff sitting in it for who knows how long, from rust. Even after honing it, the pitting is too extreme for me to consider a re-build.

I had to go through four "air-pacs" before I could get enough good parts to make one good one on my first rebuild. Then I just started to buy recent take-offs from running trucks. They at least had a chance of being rebuilt.

 

[77 AMG]

I hear ya' Rustystud. My boss is calling all of the folks that he knows in the Business that might have one, or even a lead on one. Talk about being made from "Unobtainium"!

 

[Kaiser67M715]

I had a spare air pack, that was relatively clean, and I was hoping to rebuild, but the bore ended up having some pitting, making it worthless. I didn't realize these were so hard to find now, seemed like everyplace had them for $500 a couple years ago.

Anyways, I got the air-pack all cleaned up, I took a quick hone to the main fluid bore, and as I didn't have a small enough hone, I rigged up some "00" steel wool on a wooden dowel and put it in the drill to see if I could clean up the discoloration in the smallest fluid bore. Only took a couple revolutions and 90% was cleaned up. Whatever it was appeared to be topical and non-detrimental to the bore itself.

All new seals, using some brake fluid for the brake side seals, and a combination of grease and air tool oil on the seals and felt of the air side seals. The manuals called for GAA grease in the air cylinder, and I figured using air tool oil would help keep everything clean.

Installed and let the fluid out the slave bleed, and at the outlet. I will have to bleed at the wheels another night. The misquitoes got pretty bad. I also forgot to take photos through the whole process...

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[rustystud]

I hear ya' Rustystud. My boss is calling all of the folks that he knows in the Business that might have one, or even a lead on one. Talk about being made from "Unobtainium"!

There is a Brake Rebuild shop that is installing new stainless steel liners in the worn out bores. A bit pricey but that is a option for later when there is no more left. I've found the "air-canisters" to be the biggest problem. Most are so pitted the seals will not seal or get torn up from catching on the pits. Was looking into having one made from stainless steel a few years ago. At that time I was quoted $500.00 ! Was thinking of trying my own hand at welding up one and having the machining done locally but then I found some good used ones and dropped it.