Pics of broken transfer case

[162tcat]

Does anyone have pics of broken transfer cases? Do they always break in the same spot? Just curious as to the weakness because I use mine hard on the M931 with 16.00r20's and haven't had any issues.... yet. Lots of off road equipment recovery and hauling. I have a spare t-case though. A search didn't yield any pics, just lots of stories. Considering possibly swapping one of the new Axletech transfer cases in place of mine if it does let go.

Don't need any lectures, I know how they break. My auto front axle engages via switch only, low range auto engagement has been disabled.

Thanks guys


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[simp5782]

Still operated in high range.

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[simp5782]

http://www.steelsoldiers.com/showthread.php?t=146306

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[Jbulach]

Still operated in high range. View attachment 654923View attachment 654924

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How did you brake your case?

 

[simp5782]

How did you brake your case?

Is a customers truck. Snapped pulling forward on a 130k grinder that was stuck. Its a 931 on 11.00s.

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[simp5782]

You may talk to swampdonkey. He thought of a case wrapped bracing to keep it from blowing apart under pressure

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[162tcat]

Thanks for sharing!



Here are the pics from the other thread.


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[parklandtrans]

Guy's,
Dont want to seem like it's a lecture...but MOST OF THE BREAKAGE OCCURS FROM LOAD PLACED ON THE TRANSFER CASE WHEN TRANSMISSION IS IN LOW RANGE "AND" TRANSMISSION IS OPERATED IN THE "REVERSE" RANGE AND ACCOMPANIED WITH A VERY GOOD LOAD..!!! (Overloaded..?)
After working on these units for years, I consider them to be a very well designed unit..but they do have their limitations...just like every other piece of equipment.
Thanks for the help you guys have given me when I needed it..!!
Bob/Parkland Trans

 

[bachman502]

So what transfer case could be swapped in its place to make it stronger? And from what vehicle? Thanks

 

[74M35A2]

I also have the same question as above.

 

[simp5782]

Guy's,
Dont want to seem like it's a lecture...but MOST OF THE BREAKAGE OCCURS FROM LOAD PLACED ON THE TRANSFER CASE WHEN TRANSMISSION IS IN LOW RANGE "AND" TRANSMISSION IS OPERATED IN THE "REVERSE" RANGE AND ACCOMPANIED WITH A VERY GOOD LOAD..!!! (Overloaded..?)
After working on these units for years, I consider them to be a very well designed unit..but they do have their limitations...just like every other piece of equipment.
Thanks for the help you guys have given me when I needed it..!!
Bob/Parkland Trans

They break and bust in half in high range as well as low going forward. There is no pattern to just low range

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[simp5782]

So what transfer case could be swapped in its place to make it stronger? And from what vehicle? Thanks

The mtvr 7ton would be the next closest its an oshkosh 30000. Available on gov liq to. Its just a single speed case

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[red]

Can install the T138 tcase from the older 5 ton trucks. Stronger model but you lose overdrive since the T1138 is .732:1 high vs the T138 1:1 high.

 

[parklandtrans]

Transfer Case breakage

Simp5782,
You know as well as I do if you work hard enough at tying to break something..eventually you WILL SUCCEED..!!!
Now with that being said, you have to admit that this transfer case has been one of the strongest, extremely well designed, very simple to operate and repair when required. This Transfer Case has been is service for more years then I care to even take a guess at...if I did I would have to admit I'm getting older..�������� but the fact remains that if this was a crappy design Transfer Case the our military would have dumped this in favor of another design..MANY, MANY YEARS AGO...BUT THEY DIDNT..!!
I will not argue with you or anyone else that these Transfer Cases do and have had issues or problems...but what piece of Military equipment doesn't or didn't..? Remember when the M-16 first hit Southeast Asia..lots and lots of problems but easily correct with cleaning kits and proper care and maintenance.

These units are actually over designed and overbuilt for the published ratings that they carry but, they all have there breaking points. The so called breaking point, where the unit DOES LET YOU DOWN...IS USUALLY ACHIEVED IN THE OVERLOAD/ ABUSE ARENA..!!! I have purposely overloaded my 5 ton..and I knew I was overloading the truck..WAY OVERLOADING IT..!! The thought of failure was in my mind but never came, if it had it would have been deserved..but the truck did its job again and again..!!

Everything man made breaks..everything..

Please reply back and I will respond back,

Bob 1-253-225-0441

 

[adamsoffroadperformance]

They gotta be tough. Our group has a couple M931A2's with the power turned up. We have been beating these things on road and off-road for a while dragging heavy trailers and pulling sleds and even tug of war on concrete. They have been holding up so far. On trails wheeling we use reverse in low range many times. We do unlock the diff first if possible and washer has been cut. The one farm near me has about 40 trucks in service as silage and manure trucks. The used to break alot cases but have cut it down buy not reversing in low range. The mechanic there says they only see them break when they are loaded with close to 30k lb of silage and they start to climb the silage pile and the truck hops.

 

[M543A2]

So can someone tell me how the transfers in the 900 series are different from the ones in the M series 5 tons? W have never, but as one said,---yet, had a problem in hard use in both high and low reverse. I would not like being restricted to high reverse! I have heard though that in high reverse too much load can pry a snap ring out of a shaft groove allowing a gear to move out of place causing loss of high reverse.

 

[74M35A2]

It is due to the ultra-low reverse gear ratio of the Allison MT654CR transmission that is in front of it. Reverse gearing in the range of 10:1.

 

[porkysplace]

So can someone tell me how the transfers in the 900 series are different from the ones in the M series 5 tons? W have never, but as one said,---yet, had a problem in hard use in both high and low reverse. I would not like being restricted to high reverse! I have heard though that in high reverse too much load can pry a snap ring out of a shaft groove allowing a gear to move out of place causing loss of high reverse.

They are all "M series" By "900 series" I guess you mean the M939 series 5 ton.

 

[red]

So can someone tell me how the transfers in the 900 series are different from the ones in the M series 5 tons? W have never, but as one said,---yet, had a problem in hard use in both high and low reverse. I would not like being restricted to high reverse! I have heard though that in high reverse too much load can pry a snap ring out of a shaft groove allowing a gear to move out of place causing loss of high reverse.

As stated earlier it's a different model. T1138 in the m939 series, T138 in the m39 and m809 series.

T138 is physically bigger with a stronger housing. Haven't torn one down next to a T1138 but wouldn't be surprised if the internals are a bit beefier as well.

The 10:1 reverse gear in the m939 series transmission is deeper than the 6:1 in the m39/809 series 5 speed transmission. Combine that gearing with the weaker housing of the T1138 and, well, the weaker housing makes its presence known when the driver gets on the skinny pedal in low range reverse and the truck encounters something where it can't roll over it instantly.

T1138 gearing: .732:1 high range, roughly 1.7:1 low range. Air shift to engage front ouput.
T138 gearing: 1:1 high range, roughly 2:1 low range. Sprag unit determines when front output is engaged (reliable unlike the deuce version).

If you take a T1138 and install it into a m39/809 series that has a Spicer 6453 trans (overdrive model) then you now have a double overdrive. Members here are saying they are turning about 1900 rpm at 60mph with the stock 11x20" tires.

If you plumb in a air switch to disrupt the air to the T138 then it becomes a part time unit, 4x6 instead of the sprags on demand 6x6.