Tranmission to Engine Supports

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bshupejr

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Good afternoon,

I just found out my transmission case is cracked. The transmission shop said that this is a common occurrence on these trucks when; the factory supports are removed and not reinstalled. According to the shop, there are some steel supports that go from the transmission to the engine block (sounded like to the bell housing bolts) and also one or more that go from the transfer case to the transmission to provide additional support to those items in keeping them fixed to the engine.

I have looked though the TMs and I dont see anything about these. I have looked on a couple of parts websites and Im not seeing anything like this either.

Can someone shed some light on this for me please? Reference to the TM, a website where I can buy them or at least get an idea of what they are so I can go looking.

Thank you for your help.
 

cruzer747

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If you have a TH400 I am not aware of a factory brace. There was not one for mine however for the 700r4 I retrofitted one was required. I suppose it would maybe fit with the th400 but I dont think it was oem until the lighter 700r4 came around and needed some help to resist being the weak link between the motor turning the wheels.

-edit- seems it was also around before the 700r4.... but what I gather is brace good.... no brace maybe not bad... but brace good. :)
 
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Rutjes

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Only brace I can think of is the one mentioned here. From what I recall they where not installed on CUCVs, but they where on civilian trucks?

I don't think it has anything to do with a cracking transmission housing though. What is the condition of your transmission and engine mounts?
 

cucvrus

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Hey check out this thread. I installed a few of the engine to transmission braces on OFF ROAD use CUCV's. My most used and abused was Terminus M1009. It was a very popular thread a few years back. I built the stock M1009 into a severe OFF ROAD use vehicle. Ran it a few years after resuurecting it from a scrap yard. It was 3 vehicles from the crusher when I found it. The snow plow saved it from going into the crusher. Read the thread and enjoy the journey. I found and fixed every weak link in that M1009. Then 1 day I decided to sell it and let someone else have some fun. It is still around here traveling the roads. Good Luck.
 

cucvrus

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A few issues cause transmission/transfer case tail shaft breaking. The first and this should never happen is picking up the truck from the side with a loader. The driveshaft is pushed upward dented and stress is put on the tail housing by the leverage of the transfer case being mounted on the rear housing. In normal driving conditions the front drive shaft can cause a massive breakage of the transmission and transfer case. This is caused by failure to grease and maintain the CV joint at the front drive shaft mounting flange at the transfer case. The dry CV joint cannot articulate as designed and it makes the drive shaft push back against the transfer case and causes breakage. Also the slip joint in the drive shaft has worn splines and causes vibration same as a dent in the rear driveshaft. All that vibration goes into the weak link. The tail housing of the transmission. the original TH 400 that came from the factory had a weak tail housing to begin with. I am not sure why they choose to eliminate the support braces but that don't help. I bought a new GM TH400 case 20 years ago to replace a broken case on a nice low mileage truck. The tail section on the replacement case was mush stronger and had been redesigned. So my advice would be to make sure the entire driveline is in good condition and balanced. If you have vibrations with the hubs locked fix the issue. Any vibration can cause stress. Vibration is unbalanced moving parts and it will stress everything. Including the driver. Good Luck. Be Safe and Report Back. Please? https://www.steelsoldiers.com/threads/terminus-m1009.144523/page-17#lg=post-2029331&slide=1
This is my front rebuilt drive shaft for Terminus M1009. Make sure you have all good U joints and balanced driveshafts.
 

bshupejr

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Only brace I can think of is the one mentioned here. From what I recall they where not installed on CUCVs, but they where on civilian trucks?

I don't think it has anything to do with a cracking transmission housing though. What is the condition of your transmission and engine mounts?
As far as I know the engine and transmission mounts are all fine.

Is it possible this damage that could have been done by fork lifting the truck around at some point in the past?
 

cucvrus

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As far as I know the engine and transmission mounts are all fine.

Is it possible this damage that could have been done by fork lifting the truck around at some point in the past?
A few issues cause transmission/transfer case tail shaft breaking. The first and this should never happen is picking up the truck from the side with a loader.
 

chevymike

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I have wondered if the aftermarket bellhousing would solve any cracking issues. They are used for high power applications and are SFI certified. This could be an option as well for someone with a cracked bellhousing but otherwise good trans.

 

cucvrus

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WOW. Look out I am about to apply all 140 horse power of my healthy 1984 6.2 CUCV diesel to the rear wheels. I need the blow proof bell housing, Bell housing tunnel blanket in Kevlar and a drive shaft drop loop. Stand back Women, children, and driveline let me pop this machine in gear. Spinning the tires on ice is about as good as it gets. Unless you are stuck in the mud. After hundreds of thousands of miles driving CUCV's I may have chirped a tire 5 times on the road. Just not happening with the slow burn 6.2 engine. Twin turbo's won't make it happen. Want more power? You need another engine. These are good engines but hi-power was not intended in the design. It was made to be compatible to a 305 gas engine. Be Safe.
 

chevymike

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WOW. Look out I am about to apply all 140 horse power of my healthy 1984 6.2 CUCV diesel to the rear wheels. I need the blow proof bell housing, Bell housing tunnel blanket in Kevlar and a drive shaft drop loop. Stand back Women, children, and driveline let me pop this machine in gear. Spinning the tires on ice is about as good as it gets. Unless you are stuck in the mud. After hundreds of thousands of miles driving CUCV's I may have chirped a tire 5 times on the road. Just not happening with the slow burn 6.2 engine. Twin turbo's won't make it happen. Want more power? You need another engine. These are good engines but hi-power was not intended in the design. It was made to be compatible to a 305 gas engine. Be Safe.
The idea isn't just high power use but being a very heavy duty bellhousing, it is likely you could never crack one of these with all of that leverage and weight hanging off the back. Since there are people who have cracked bellhousing, this could be used to save an otherwise good transmission. The 6.2 diesels will never "overpower" the trans but bouncing around offroad can put a strain on the bellhousing, especially if your rear trans mount is bad (which should be replaced anyways).

Just sharing an option that might help someone out. Being I am into the offroad, hot rods and classic car worlds, I find I can source upgraded parts from other areas, to solve problems. I know you are totally a 100% stock person and that is cool but if stock was perfect, there would be no aftermarket world, making parts to fix problems of the "perfect stock" world. Stuff breaks and if I am going to replace something, if I can replace it with an upgrade that eliminates a weak point, why not?
 

cucvrus

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I only ever seen 2 CUCV TH400 bellhousing broken. Both had massive damage from being in a accident. Most times the rear flange and area around the governor plate are cracked and that comes from lifting. I am just saying you don't need to empty the bank account to make a tough reliable CUCV for OFF ROAD. Most of these have been OFF ROAD most of their military lives and passed the test of time. I had issues with crushing the transfer case against the floor on my OFF ROAD M1009 and all I done was make a better cross member. https://www.steelsoldiers.com/threads/terminus-m1009.144523/page-17#lg=post-2030442&slide=0
And that was the end of that issue. I went to Trucks Gone Wild in Yankee Lake Ohio and ran all weekend. I high centered it several times and the stuffing of the transfer case was a thing of the past. I know they make parts for hot rods and off road vehicles. I am only helping out by pointing out that to spend that on a CUCV would be a waste of money. The CUCV will not put out enough power to make it even worth while. In my opinion a good rebuilt transmission and balanced drive line would be wiser money spent. Some guys cut mufflers off stock trucks and it becomes a pre-runner desert racer. Have a Great Memorial Day Weekend and get that American Flag out and flying. Be Safe.
 

dougco1

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WOW. Look out I am about to apply all 140 horse power of my healthy 1984 6.2 CUCV diesel to the rear wheels. I need the blow proof bell housing, Bell housing tunnel blanket in Kevlar and a drive shaft drop loop. Stand back Women, children, and driveline let me pop this machine in gear. Spinning the tires on ice is about as good as it gets. Unless you are stuck in the mud. After hundreds of thousands of miles driving CUCV's I may have chirped a tire 5 times on the road. Just not happening with the slow burn 6.2 engine. Twin turbo's won't make it happen. Want more power? You need another engine. These are good engines but hi-power was not intended in the design. It was made to be compatible to a 305 gas engine. Be Safe.
Easter Find loves chirping tires when I pull out of my driveway. It must be the combination of my heavy foot, the shift kit in the rebuilt tranny, and the locker in the rear.
 

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Sharecropper

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Some more Googling and more horror stories... I already wanted one, now I want one even more. Might be a hard to get part, but looks easy enough to make one.
That brace rod which runs from the side of the NP208 to the engine block is GM part #14020856. They are on Ebay all the time. Search np208 brace rod in Ebay Motors. The bolts are usually on there as well, however you can pick these up at a John Deere place new a little cheaper. They are metric M16 x 40.

Hope this helps.
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