M923 Trans question

[diverman555]

I was told today by a friend who is a Staff SGT. in the reserves and works full time
repairing these trucks, that if you have the truck in low gear NOT to put the truck in reverse or the trans will litteraly explode from the pressure.
He said just putting it in reverse with it in low gear will make it violently explode.
Has any one heard of this before?

 

[gungearz]

I've never heard of such a thing... Of course I don't own a 5 ton. Let's see what these other guys have to say.....

 

[doghead]

Correct warning, wrong explanation.

Isn't this covered in the TM?

Do not use low range reverse. Some trucks have a modification to lock this out. The transfer case can break.

 

[diverman555]

Don't know if it is in the TM's, but since this was such a expensive problem I thought I would post what he said so many other people would hear.

 

[doghead]

I'm not sure either. That's why I asked. (I don't own one of them, yet)

This kind of info(assuming it is documented somewhere) is why we should read the TMs. It could save you a lot of trouble.

I agree, posting it can be helpful as well.

 

[doghead]

Yes, it's in the TM 9-2320-272-10

Do not back up with transfer case shift lever in low range.

The -10 is the basic operators manual.

Do you see the value in reading it now, and being familiar with proper operating procedures now?

This would be a very expensive lesson.

BTW, I don't have the TMs for this truck downloaded, and I am not very familiar with them, yet I was able to answer your question quite easily with a few minutes of searching the Internet and reading the TM.

 

[AaronW]

There is a warning for this on my dash data plate. Of course they left out the "or it will explode" part. Probably ran out of room on the data plate......

 

[jedawson1]

My M923A1 has a warning painted on the windshield and a lock out on my shifter. I dont believe it will explode the instant you place it in low reverse, I think it drives the pressure up when you hit the gas and any kind of load or hitting the gas is more than it can handle in low reverse. Then it's Kaboom.

 

[BKubu]

I accidentally put my truck in reverse in low range once...it was the first time I ever got into an M939 series truck and it was already in low range and I had to back it off of the trailer. Nothing happened. If you were just idling or even applying very limited throttle, you'd be fine...but the risk is there and that is why they tell you NOT to do this. My recommendation is to follow the warnings and not try it out yourself. I have never done this since even though nothing happened the one time I did try it. No reason to tempt fate as transfer cases are expensive and difficult to swap out. By the way, I have been told the problem lies in the amount of torque transfered from the motor through the transmission and into the transfer case in low range...the t-case cannot handle it and this is what splits the case.

 

[diverman555]

The Staff SGT. told me it was because of the huge pressures in the case, that is why he said it blows up. I kind of believe like you what is the purpose of tempting this thing. I would just rather be safe and not try it at all.

 

[diverman555]

The SGT% did say that there is a mod to make sure that you can't do it. He looked under my trucks did not have it but it keeps you from shifting into reverse with the shift lever in low range.

 

[juanprado]

I would be interested in finding out what is the mwo number and a tm or instruction write up on it. Mine only has one tag for the ABS so I don't think I have this change done on it.

Can anyone shed light on what was done and the parts involved?

Thanks for your help!

 

[BKubu]

Yeah, I've never heard of that MWO, but someone who is serving would know best! Keep us posted.

 

[wsucougarx]

There's a little info in the PS Magazine that I came across. Now if I can only find it now... Thought the cracked cases were from too much torque.

 

[BKubu]

There's a little info in the PS Magazine that I came across. Now if I can only find it now... Thought the cracked cases were from too much torque.

That is what I posted also. My info came from a guy in the NG.

 

[diverman555]

I just talked to the sgt and he cam get the mwo Tuesday when he gets back in town.

 

[doghead]

And let's not forget searching and or being slightly familiar with the 5 ton forum posts.

I'm pretty sure you owned one of these trucks a year ago, when this thread was posted.
http://www.steelsoldiers.com/5-ton-up/72463-m923-reverse-shifting.html

or this one, http://www.steelsoldiers.com/5-ton-up/83398-m923a2-reverse-question.html

and this one, http://www.steelsoldiers.com/5-ton-up/53683-m923a2-tranny.html

and, http://www.steelsoldiers.com/5-ton-up/81594-bought-m931-now-what.html

It might be a good idea to just sit and read the forums(if you think you cant search).

 

[diverman555]

I got my first truck in Nov.

 

[nf6x]

I saw one of the reverse lockout kits listed on eBay about a month ago, but it was for the A2. There is a different kit for the A0/A1 trucks. I found references to the MWO kit part numbers in one of my TMs, but I don't recall if I have the installation instructions for the MWO. I'm not in front of my computer right now.

I am keeping my eyes open for at least one kit for my M923, and possibly a second one for my new M936A1 which is still in the GL yard. If anybody scores one of the kits, it would be great if they post lots of pictures of it on SS.

My M923 came with a handwritten tag tied near the lower left corner of the windshield warning not to use reverse in low range. I have seen this discussed here before, including the explanation that it is not an instant grenade, but has a high risk of cracking the transfer case housing due to excessive driveline torque.

 

[doghead]

I was just doing a Google search for the MWO. That's where I found the links posted above. There are many others also.

Still looking for the MWO. I just had a discussion about this last week.

When I have more time, I'll look more.