My BIG M925A2 Project Truck Is Home

[cranetruck]

This is the 1969 version of the separator (NSN 2530-859-7279). The treated air is used for pressurization of cab/engine components and brake drums.

 

[steelsoldiers]

This is the 1969 version of the separator (NSN 2530-859-7279). The treated air is used for pressurization of cab/engine components and brake drums.

Nice old-school separator! Do you get much moisture out of it when you dump it?

 

[cranetruck]

Nice old-school separator! Do you get much moisture out of it when you dump it?

Don't run the truck enough to notice anything yet. The system has a factory installed alcohol evaporator, so there is always a trace of moisture/alcohol in the air tanks since I have the jar filled to some extent at all times.
The CTIS on your truck may be more sensitive to dirty air then anything on mine, though.

 

[neilhendrix]

I saw that truck a couple of weeks ago when were at John`s picking up my M109 . It will be a fine ride

 

[steelsoldiers]

Thanks Neil. Hope you are enjoying that 109. Hopefully we can do that outer banks trip next year that we've all been talking about and get us all together.

 

[steelsoldiers]

Brake Chamber Rebuild

I have been searching for air brake chambers with no real success. People either wanted too much money for the chambers or had them listed in the system, but didn't have any on hand. I went to my local NAPA Truck and showed them what I was looking for. Out came the huge Bendix book. He took some measurements and found a match. Problem is Bendix doesn't stock them so it would be a custom run and could take a month

I decided to try my hand at rebuilding a chamber. I ordered a couple of new actuator diaphragms from NAPA for around $3/piece. I tore into one last night to see what I had to work with. That sucker was full of rust! Thankfully, Rockwell painted their brake chambers on the inside too so most of the rust scale came right off. Once I had it apart, I took it to the kitchen sink and scrubbed all of the parts with a brass bristle brush. I got it looking pretty nice so back to the living room for reassembly (yes, my wife is understanding and working on truck bits in the house is nothing new ). I installed the new diaphragm, stuck the high pressure half on top of that, installed the clamp ring, and torqued down the clamp bolt. Viola! An almost new brake can that you can build in your living room!! I only wish I would have brought the other one home too. Now, I have to redo it on the ground.

Just in case anyone needs to know, the brake chambers are Type-12 Wedge Brake Chambers and they take a Rockwell 2297D2448 Diaphragm (or Midland N-20166 T-12). There is only one moving part inside the chamber and that is the actuator rod which is machined out of heavy steel so there is very little to go wrong with these things.

Here are some photos of course!

 

[cranetruck]

You learn a lot when you can't get a new one. Been there, done that sort a thing...again and again.
I suspect that even the parts truck would have questionable replacements.

 

[steelsoldiers]

You learn a lot when you can't get a new one. Been there, done that sort a thing...again and again.
I suspect that even the parts truck would have questionable replacements.

Very true! The parts truck was in the same shape because the air lines had been disconnected on those chambers too. At least now I know the diaphragms are good and that it's been done right. The more I work on the air brake system, the less intimidating it becomes. I didn't have to do much with the brakes on the 923A2 so a lot of this stuff is new to me, but it's really pretty simple once you break it down into its components.

 

[OLDCHEV4X4]

Once I had it apart, I took it to the kitchen sink and scrubbed all of the parts with a brass bristle brush. I got it looking pretty nice so back to the living room for reassembly (yes, my wife is understanding and working on truck bits in the house is nothing new ).

Using the kitchen sink as a parts washer!!!!!
And the coffe table , no doubt, as a assembly work bench!!!!
You do have a very understanding wife. Does she have a sister???

I have been following along since the start, and enjoy the updates. Keep up the good work.

 

[steelsoldiers]

Sorry, no sister, Randy! I'm OK so long as there's no grease on anything when I get done. We have a 2 year old boy at home so I can blame some stuff on him now. He likes to play on and around daddy's trucks so the grease could come from him, right?

 

[Oldvw2]

Sorry, no sister, Randy! I'm OK so long as there's no grease on anything when I get done. We have a 2 year old boy at home so I can blame some stuff on him now. He likes to play on and around daddy's trucks so the grease could come from him, right?

And you can't forget the dog - chocolate labs could track a lot of dirt in and you wouldn't see it on them, right?

Nice job on the brake chambers - now all you have to find is the flex lines.

 

[4x4 Forever]

Been following and all I gotta say, you are gonna have one outstanding truck when you are finished. Keep up the good work!!

Read earlier about your concerns on the wiring. You might want to keep your eyes open for a NOS wiring harness though. I know you dont want to hear it, but when saltwater gets into wiring, it travels up the wire. We've had to change out the exterior wiring on the offshore boats I ran. Even with cleaning, crimping/soldering, and sealing, the corrosion keeps going.

Keep your head up!

 

[steelsoldiers]

Been following and all I gotta say, you are gonna have one outstanding truck when you are finished. Keep up the good work!!

Read earlier about your concerns on the wiring. You might want to keep your eyes open for a NOS wiring harness though.

Thanks!

Funny you should mention that. I have a listing in the classified ads looking for one already One of our fellow members has a good take-out harness so I may go that route if nothing else turns up.

 

[southdave]

Hey Chris I have couple of Type 9 mgm ( came in box -crap from GL) looks the same without big nut on top they brand new and there are some numbers mgm 1009101 also have foot valve for the 900 seris

 

[srodocker]

Wow i have also been following along on this build....what a inspiring build! why is it these latley these trucks have been coming off GL in horriable condition?

 

[BFR]

Wow i have also been following along on this build....what a inspiring build! why is it these latley these trucks have been coming off GL in horriable condition?

As a taxpayer I would be livid If I saw a 939 series truck in good condition surplussed.

 

[steelsoldiers]

Wow i have also been following along on this build....what a inspiring build! why is it these latley these trucks have been coming off GL in horriable condition?

Thanks!

The Army has an ongoing rebuild program for these trucks so most of the ones coming out are wrecked, rusted out, or have been sitting on the can-lot getting picked like a chicken! If they are beyond some reasonable return-on-investment percentage for rebuild, then they go to DRMO. That's the way I understand it anyways.

 

[steelsoldiers]

Dang!

I realized tonight when I was looking up the brake actuator part number that I put the diaphragm in upside down. The exploded parts diagram showed it opposite of the way I put it in. I took it apart and flipped it. At least I found out before I tried to use it

Here are some pics showing the diaphragm installed correctly just in case anyone uses this behemoth thread for a reference

 

[frodobaggins]

Sorry, no sister, Randy! I'm OK so long as there's no grease on anything when I get done. We have a 2 year old boy at home so I can blame some stuff on him now. He likes to play on and around daddy's trucks so the grease could come from him, right?

Nope, wives don't work that way. Any grease on him from YOUR truck is YOUR fault !

 

[steelsoldiers]

LOL! Yep, you're right. Doesn't matter if she was watching him when he got greasy. It's still my fault. "Your son tracked grease in the house after he was playing on your dirty army truck!"


"Honey, if you are reading this, remember that I love you!"


Thankfully the 5-ton has been at Winslow's so my boy hasn't been around that EPA Superfund site!