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M925A1 "Brake Chamber" issue?

simp5782

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Don't know till you look at it. If i come down and look at it. I have a trailer to put it on. Depending on how far it is going. Cashs talk and B.S. walks. Show up with 5000 in cash in hand and people don't tend to think on it especially if you are going to walk away. Not to mention someone who knows what they are looking at and can point out 5 to 10 things wrong with it within being in the drivers seat 2 minutes. I am sure the air dryer purge valve sticks. especially if he doesn't use it like it looks.

You have to remember also on these trucks every re re and tom and jerry calls or wants to look at em and doesn't know a thing about them. or they want an army truck but don't have the money. That famous "i have always wanted one of those" makes me want to hang up on folks.
 
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Aolinge1

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Yessir! Wise words. I just talked to him and he said he's away and won't be back until the 25th. When he gets back I'll try and see to get the process rolling unless I find a better deal on something else.
 

98G

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Jericho, what type of shops could do it? everyday mechanic shops?
Tag with date of manufacture will be on the drivers side of the engine. It almost certainly says 1984. However, I've seen four that say 2007.....

Any place that works on large over the road trucks can work on these. Ideally you want to learn to do just about everything yourself. These things are pretty simple and straightforward.

The brake thing isn't complex, it just carries a very high penalty for mistakes. In a perfect world someone who has done it before would walk you through it.

Consider having simp haul it for you. You can probably talk him into giving you a crash course on these trucks at hand off.

I looked at the pics again. I'm not seeing a bed tilt. I think it's just the G177s.

I forgot to mention earlier, seller says new tires. Extremely unlikely. I'll be they're date code 2002 ... they probably look fine, but they can do this with no warning -

Screenshot_2018-05-11-18-51-51.jpg

Me on the side of the road in my M925 when a fine looking G177 let go without warning....
 

Trailboss

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in his ad he says:

5 ton military truck runs and drives great. Redone at 2000 miles by Red river Army. Has 3063 miles. Need to change the brake chamber on right rear. Sold as is. No title. Used as farm vehicle. 8.3 Cummings motorNew tires New batteries2 inch trailer hitch.With winch
From the photos, tires are not new, but have good tread and should be OK. Looks like the brake chamber is in pieces on the ground - not sure if the service brakes lock or are free with the chamber removed, but the other brakes will probably have to be caged or that air line plugged before the truck can roll or drive. That truck is a M925 base model, not M925A1, and it comes with NTC 240 Cummins - not 8.3 Cummins. The winch has no level winder (not really required and is often missing), and it looks like the cable has a kink. The cab top is coming loose in the front, so will need repairs or go to a used hard top for about $500. Not sure what that can is doing over the fuel tank.
 
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juanprado

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If the truck has the original bill of sale from GL or GP and sf97 with reassignment, then you could title it in your state. If it has been used in La as farm truck, it would have a title and farm plates.

I would ask hard questions as why no title. La registered military trucks up to 2 months ago with no issues. All on hold at present till Bill passes. Earliest La will be back to registering/title mv's is Jan 2019.

Paint is suspicious to me as truck started Green, painted tan, and now 3 color over tan. Screams rattle can quick paint job.

There are several members close to Walker. TimnTrucks in Ponchatoula is one that maybe can inspect for gas money? I am hour+ away so not too close to me.
 

mdainsd

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That truck being an A0, look right inside the drivers door for a MWO tag numbered MWO 9-2320-272-35-1, or for a indicator light on the far left of the instrument panel that is labelled "ABS". If those are not there (but it is likely they are), know that the truck has safety issues. That isn't my opinion, that comes from the U S Army. The kit to correct that is available but is around 6 hundred dollars. Also if you are not comfortable installing it the cost of having someone do it could easily be more than the kit was. JUST GO INTO IT WITH EYES WIDE OPEN.
 

simp5782

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That truck being an A0, look right inside the drivers door for a MWO tag numbered MWO 9-2320-272-35-1, or for a indicator light on the far left of the instrument panel that is labelled "ABS". If those are not there (but it is likely they are), know that the truck has safety issues. That isn't my opinion, that comes from the U S Army. The kit to correct that is available but is around 6 hundred dollars. Also if you are not comfortable installing it the cost of having someone do it could easily be more than the kit was. JUST GO INTO IT WITH EYES WIDE OPEN.
The drivers side window has the ABS sticker.

and

That is your opinion that ABS is a safety issue. I log more miles in a M939 truck than anyone. Loaded trailers. Unloaded trailers. Loaded beds and unloaded beds. I have NEVER locked the brakes up and I have had several emergency stop situations. And I would rather not have ABS. I actually took it off of my truck. If you know how to properly drive the vehicle you do not have an issue. Otherwise you should not be in the drivers seat of a 22,000 lb truck. The ABS issue is mostly like snowtrac nome said iced over roads as well as some gravel roads maybe. The army did it as a liability to cover their butts. Notice the marine corp and navy did not follow suit and they had 1/3 the trucks to outfit than the army. Hint as to why your truck doesn't have it. It takes A LOT to lock it up and kill the truck on a pavement.
That is your opinion that ABS is a safety issue. I log more miles in a M939 truck than anyone. Loaded trailers. Unloaded trailers. Loaded beds and unloaded beds. I have NEVER locked the brakes up and I have had several emergency stop situations. And I would rather not have ABS. I actually took it off of my truck. If you know how to properly drive the vehicle you do not have an issue. Otherwise you should not be in the drivers seat. The ABS issue is mostly like snowtrac nome said iced over roads as well as some gravel roads maybe. The army did it as a liability to cover their butts. Notice the marine corp and navy did not follow suit and they had 1/3 the trucks to outfit than the army. Hint as to why your truck doesn't have it. It takes A LOT to lock it up and kill the truck on a pavement.
 

98G

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I'm old enough that I learned to drive before ABS was in widespread use. I had been driving years before I ever drove a vehicle with ABS, including OTR tractor trailers.

On most vehicles ABS is a bandaid for lack of driver skill.

On these, the ABS is a compensatory mechanism for that auto transmission. There's no clutch to disengage the driveline.

ABS is highly desirable on these trucks. The army considered it necessary enough to go back and retrofit. Once they did, the fatality rate dropped dramatically. This fact alone should scream! Nothing says 'effective' like a statistically significant change in results over a large sample size.....

It's easy to say, "yeah but those are clueless 18yo drivers. I'm better than that." Maybe, maybe not. Those clueless 18yo got training specifically for these vehicles that included threshold braking and they were still rolling them.

I'm reasonably experienced, have specialized driving training beyond the norm, and have driven these trucks more than most people (exclusive of Simp). Twice I've hit the brakes hard enough to activate the ABS....

Again, emphasis - on any other vehicle ABS isn't so important. Lock up the brakes and you can recover. But on these vehicles lock up the brakes and you kill the engine and lose your power steering as well. So, either fix the underlying problem of the torque convertor or have the ABS to offset it. (As an aside, I notice Simp has a different transmision that doesn't include the offending combination).
 

simp5782

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I'm old enough that I learned to drive before ABS was in widespread use. I had been driving years before I ever drove a vehicle with ABS, including OTR tractor trailers.

On most vehicles ABS is a bandaid for lack of driver skill.

On these, the ABS is a compensatory mechanism for that auto transmission. There's no clutch to disengage the driveline.

ABS is highly desirable on these trucks. The army considered it necessary enough to go back and retrofit. Once they did, the fatality rate dropped dramatically. This fact alone should scream! Nothing says 'effective' like a statistically significant change in results over a large sample size.....

It's easy to say, "yeah but those are clueless 18yo drivers. I'm better than that." Maybe, maybe not. Those clueless 18yo got training specifically for these vehicles that included threshold braking and they were still rolling them.

I'm reasonably experienced, have specialized driving training beyond the norm, and have driven these trucks more than most people (exclusive of Simp). Twice I've hit the brakes hard enough to activate the ABS....

Again, emphasis - on any other vehicle ABS isn't so important. Lock up the brakes and you can recover. But on these vehicles lock up the brakes and you kill the engine and lose your power steering as well. So, either fix the underlying problem of the torque convertor or have the ABS to offset it. (As an aside, I notice Simp has a different transmision that doesn't include the offending combination).
It applied before the CAT swap as well. pump to stop not slam em on. Let the shoes get a better grip with each release and application.
 

98G

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It applied before the CAT swap as well. pump to stop not slam em on. Let the shoes get a better grip with each release and application.
No argument. Your braking description used to be the standard, taught to everyone for every vehicle. Now they just teach "stomp it and let ABS modulate".

In the early days of ABS a skilled driver could get a shorter stopping distance than ABS. That hasn't been the case in quite some time.

Still, in most vehicles I could care less whether it has ABS or not. My 939series are the only trucks I actually want it in.

Let's digress and talk a moment about limits. Limits in anything. The only way to precisely define a limit is when you exceed it. Bursting strength on a line for instance. You put 1000psi on it. It didn't burst. You still have no idea whether the actual limit is 1001 or 10,000. You start adding pressure in 1psi increments. You still have no idea what the actual limit is, only that is is higher than what you have already applied. The line bursts at 1081psi. Now you can stick a hard number on the limit strength of the line at 1080psi. But until you exceeded it you had no idea.

Apply this to braking a 939series truck. You hit the brakes hard. They didn't' lock up. Obviously you weren't at the limit and could have hit them harder. How much harder? No way to know for sure until you lock them up.... with ABS in place you know you hit the limit when the ABS actuates. Without it you know you hit the limit when they lock up and kill the engine.

Experience gives us a good idea where we'll find the limit. This experience is informed by previous instances of exceeding the limit and extrapolation from similar experiences. But exceeding the limit of braking on a 939series truck without ABS has potentially dire consequences.

These big airbrake trucks handle differently than a pickup truck. Many people getting into the MV hobby don't' have experience driving anything more than a pickup truck. Lockup an m818 without ABS and you can recover. Lock up a 939series truck without ABS not so much.... an m818 had a manual transmission....

Further, a 939series truck brakes a lot different than a large civvy dump truck. My experience has been that a 939series truck will potentially lock up the rears much more easily than an empty civvy dump truck of roughly the same class. In the two instances where the ABS activated, I didn't think I was all that close to the limit.

So, applying experience from a pickup truck will bite you. Applying experience from a heavy-ish civvy truck will also bite you. And no vehicle other than a 939series truck without ABS has quite the same penalty for exceeding the braking limit.

This comes up every time the ABS is mentioned. "I'm a good driver. I learned without ABS. I don't need ABS. Only the incompetent inexperienced need ABS." With the dumbing down of everything in our world today, it's easy to dismiss the ABS as just another unnecessary safety feature. But the M939series truck is a different animal. The ABS on these trucks isn't about fixing driver skill - it's compensation for the deficient transmission/torque converter. Fix that torque converter and then you can relegate ABS to the category of unneeded safety device.

All of this is completely irrelevant to this thread though. The truck the guy is looking at has ABS.
 

fasttruck

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Air leakage ? DOT allows 2psi/min with parking brake released and 3psi/min with service brake applied. Any leak you can hear probably exceeds these parameters.
Check applicable -20 manual for this truck. It should describe how to change out a brake chamber. If SERVICE side has a leaking diaphragm these can be safely
replaced at home. Check parts book for NSN or take old one to store with you to match it up. I believe they are what the trade calls a type 30 diaphragm.
 
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