M1028 Cracked Transmission Case

[MachoTime96]

Just found a crack in the rear of the Transmission case on my 1984 M1028. Thinking of replacing the entire thing.

Any videos, links, advise is appreciated, thank you in advance.

 

[MachoTime96]

 

[Mullaney]

View attachment 921390

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Yessir, I believe you will need a replacement case.
Did you "dog" your truck, or was it already broken when you got it?

 

[MachoTime96]

Not sure was "dog" means but i dont believe it was broken when I got it. I drive it carefully on mostly pavement.

 

[Mullaney]

Not sure was "dog" means but i dont believe it was broken when I got it. I drive it carefully on mostly pavement.

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Okay, what about the motor / transmission mounts? Are they in good shape? Generally speaking, a transmission will only get cracked if it is under a load (torque) and maybe the mounting was loose. I can't imagine it just sitting there and getting a crack in it.

 

[Barrman]

Fork lift loading to sell at auction has done that many time in the past.

 

[MachoTime96]

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Okay, what about the motor / transmission mounts? Are they in good shape? Generally speaking, a transmission will only get cracked if it is under a load (torque) and maybe the mounting was loose. I can't imagine it just sitting there and getting a crack in it.

You may be on to something. I noticed my rear drive shaft was dented. The previous put a tire weight to offset the dent when it spins. This could be a factor. Ive yet to check the motor mounts. But ive never noticed them being worn.

 

[78bigten]

Last year my 1985 M1008 transmission had a crack at the rear of the case. The crack was on the top, close to where the transfer case mounts bolts to the transmission case.

I have owned the truck for close to ten years now. I don't off road it hard or tow much with it. It was my daily driver for the first four or five years I owned it. I did replace both the motor mounts and the transmission mounts when I first bought the truck.

I was lucky to find a transmission out of a CUCV in a junk yard a couple of hours away. The replacement transmission had HD cast into the bellhousing.

The transmission that came out of my M1008 did not have HD cast into the bellhousing. I believe the HD transmission case had reinforcements made to the rear of the transmission case, to help support the transfer case.

I can only guess that a previous owner had replaced the transmission before. And the weight of the transfer case cracked the transmission case.

 

[Curtisje]

Maybe you need the support rod for the transfercase? I don't know much about them but there is a thread on here about it.

NP 208 transfer case brace

Just want to point out again that I have yet to see something built in the last 20 years have anything remotely close to a torque rod on the tcase, never seen one on a Japanese import truck, nor anyone adding one aftermarket. As you probably already knew, early Jeeps had a simple setup that...

www.steelsoldiers.com

Good luck.

 

[royalflush55]

You can also crack the transmission case by being in low range transfer case and hard pull in reverse.

 

[biscuitwhistler37]

Look for dents/scratches/marring on the frame near the dent in the driveshaft, I've seen many a bent one from fork lift loading. The off balance driveshaft may have caused the crack as well if it were severely out of balance, but I'd think you'd feel that going down the road. If you could post a pic of the driveshaft bend that might help us draw a better conclusion.

 

[cucvmule]

That small of a crack can be easily fixed by welding. I have repaired bellhousing cracks that were fully separated in 2.

I have another military case separated at the rear adapter flange that lost the upper bolts and left the bottom 2 that broke out.

It is beyond repair but hopefully all the heavy duty internals are worth the transfer to another case. The mainshaft spins true so until the case gets broken down to see any further damage will depend on what gets saved.

Finding a good core is getting harder by the day. Every military core I pay 100 bucks for broken or not.

The 4 wheel truck cases are different from the passenger car and light duty trucks. Turbo 400 and some Turbo 350's the inspection cover for the torque converter on the HD trucks get bolt on covers to make the case more ridged at the bellhousing and provide for bolt on reinforcing bars to both sides of the engine to each motor mounts. On the 205 cases GM used an additional bar that went from the transmission bellhousing bolt to the right rear outside of the T case, and if memory serves like Curtisje stated the 208 uses the same T-case bar.

And why the military trucks did not use one noone really knows.