need info on M923 ,Big case

[OilfieldRoughneck]

Wow, speaking of MODS! You realize Steve (swbradley) is a mod right? You do know telling him you will disobey the site rules when you want and to just move a long may not be the wisest thing to do.
Alrighty then!

Bad spelling and punctuation is against site rules? News to me.

 

[phil2968]

Copied from rules......
• Do not post in all CAPS or in giant run-on sentences without punctuation. Do not post as if texting and do avoid the use of texting abbreviations. We are not the grammar police but we want everyone to easily read your post in at least 8th grade English. It is extra work to post proper sentences from a smartphone but the result will be greatly appreciated. Please do your best to use capitalization, proper spelling and punctuation. It makes it easier for everyone to read! Note: this is a RULE, and is enforceable.*

 

[swbradley1]

Bad spelling and punctuation is against site rules? News to me.

It's frequently news to a lot of members who don't read the rules.

 

[spicergear]

Someone posted a pic of the mod that eliminates the front axle automatically engaging when putting the transfer case in low. It was as simple as removing a washer from the high/low linkage.
http://www.steelsoldiers.com/showthread.php?83799-M939-transfer-case-air-lines-installed-wrong Post #11
Sure you won't have the front axle locking in when going in reverse, but it beats a broken transfer case. In any case you should NEVER have the front axle locked in when going in reverse.

Yep, that was me. PULL THAT WASHER and get on with driving the truck. With the washer off, you only will be driving the tandems in low reverse not the weighted and planted front tires; you'll be able to pull them in via dash air switch when YOU want. I use my truck offroad hauling logs a LOT and I've had to low range and reverse out of ugly places loaded and have no fear because of how the power is applied. The truck works, plain and simple.

 

[floridastateo8]

Newbie here. I reversed in low and cracked my transfer case in a 1983 M923A0! I should have read the TM's first!

Has anyone ever tried welding these cases? Are these cast iron or cast steel housings? I can't find details after many searches trying different keywords. Any help is appreciated!

 

[Jericho]

Install the low range reverse lock out mod and solve that problem

 

[floridastateo8]

Jericho - That will just prevent me from cracking it again once it is fixed, right? Do you have any suggestion on how to weld / fix the crack? Here is a picture. The crack is only 2 to 3 inches long, starting at the fitting, and going about half way to the flange.

Mods - I don't mean to hijack this thread. If I should start my own, I am happy to.

 

[simp5782]

You cant give it gas in reverse. They can back up in reverse without damage. You cant fix it. You may talk to swamp donkey but the case is toast. Take it.apart you will find all kinda pieces for the pressure it.flexed.and caused the crack

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[Jericho]

The reverse lock out kit wont help at all if your case is already cracked. I have welded many cases, transmission, reduction gear, transfer, Of those I have only one that didn't eventualy crack again. I cant say that I have ever seen just a case for sale, On cast nodular steel ,I clean , pre heat, and weld with 7808 rod, , continue to apply heat as it cools gentily, on aluminum I have used filler rod, Contamination is the scurge in AL, clean well and use inert backing gas during welding. A very good welder can weld it in place upside down (bottom crack) , unit must be drained and degreased, worth a try, if the alternative is removal anyway, best way to get a good weld is to strip it and weld from both sides, inside and out.Have had reasonable luck doing that on cast and AL . I know they run 12 to 1800 $ to replace, by the time you have it out and disassembled , may as well change it

 

[Jericho]

I must say Simp has more practical experience with the 900 series and mileage than anyone I know. I glean what I can from him and Swamp on a regular basis. I do have the lock out kit installed on my 931, but did use reverse low prior to install. Replacement is easy and straight forward, JUST HEAVY , use a good lift on stable surface!

 

[wheelspinner]

Newbie here. I reversed in low and cracked my transfer case in a 1983 M923A0! I should have read the TM's first!

Has anyone ever tried welding these cases? Are these cast iron or cast steel housings? I can't find details after many searches trying different keywords. Any help is appreciated!

This item is so important that they included the warning on the yellow tags right there on the dash. Did your truck have those?

 

[Jbulach]

Jericho - That will just prevent me from cracking it again once it is fixed, right? Do you have any suggestion on how to weld / fix the crack? Here is a picture. The crack is only 2 to 3 inches long, starting at the fitting, and going about half way to the flange.

Mods - I don't mean to hijack this thread. If I should start my own, I am happy to.

View attachment 684888

Are your sure that crack was caused by low range reverse? I don't think that's a typical stress/break area, looks to me like it may have broke due to over tightening of the reducer fitting...

 

[Jbulach]

The reverse lock out kit wont help at all if your case is already cracked. I have welded many cases, transmission, reduction gear, transfer, Of those I have only one that didn't eventualy crack again. I cant say that I have ever seen just a case for sale, On cast nodular steel ,I clean , pre heat, and weld with 7808 rod, , continue to apply heat as it cools gentily, on aluminum I have used filler rod, Contamination is the scurge in AL, clean well and use inert backing gas during welding. A very good welder can weld it in place upside down (bottom crack) , unit must be drained and degreased, worth a try, if the alternative is removal anyway, best way to get a good weld is to strip it and weld from both sides, inside and out.Have had reasonable luck doing that on cast and AL . I know they run 12 to 1800 $ to replace, by the time you have it out and disassembled , may as well change it

What is nodular cast steel and a 7808 welding rod? Neither sounding familiar to me...

 

[Swamp Donkey]

I assume you have driven it after it cracked? Any strange noises or vibrations?If not, I'd try to repair that.

The crack doesn't go all the way to a mating surface so I feel you have a good chance at saving that case. The case was cracked but not completely broken. Noises or vibrations would confirm that the internals have moved or broken like Simp said though. It does appear to be more related to overtightening of the fitting though like Jbulach mentions.

That crack should be stop drilled, cleaned and then brazed instead of welded. It's a meticulous job to prepare that spot to braze it properly without disassembling that case. The hard part is removing the contamination. Multiple cleanings and heatings after the case is drained will be required. Non-flammable brake cleaner will be your friend here. Leave the fitting in until you have it completely cleaned. Removing it will close the crack. Since it's an NPT fitting there is pressure in the hole from the interference fit. This is good when you get ready to braze it but you need it open to clean and Vee it out.

If you don't know how to braze then find an old school transmission/driveline shop. They most likely won't do it in house but will know somebody that can. The old school shops will attempt to repair stuff like this but will most likely contract out the work. The newer shops are all about replacement these days and mentioning brazing will get you some blank stares.

There's a local guy to me that would do it and guarantee the repair but that doesn't help you much. I have a good T-case with a broken front output shift fork I'd let go for a decent price. Simp has the replacement shift fork and it's simple to install. I'd of done it already but Simp is a busy man and hasn't been able to drop it by yet. The fork in your case is probably still fine and could be swapped over. I have a reduilt case in a can but don't care to part with it.

All this assuming the internals were not damaged. Repairing without pulling the case would be the easiest outcome. If you have to pull the case, I agree that a different one should go back in.

Wish I had known about this last weekend. I'm in Destin right now and could've thrown it in the truck.

 

[floridastateo8]

Wow. You all are a wealth of information. I appreciate the willingness to help.

Wheelspinner – I do have the yellow tags on the dash. I was competing in a truck pull contest. I admit that I reversed in low - shifting from high to low in the truck when under pressure is a challenge. Did the case crack as a result of the reversing, or as a result of the multiple truck pulls? I can’t answer that question.

Jbulach - The crack may have been a result of the NPT fitting being over tightened. I imagine that helped cause the crack, however, I don’t believe it cracked during the tightening. It was probably a combination of the pre-stress of over tightening combined with the extreme use during the truck pull (or reversing in low range).

Swamp Donkey – I drove it home after the truck pull and it drove just fine. Now that all of the gear oil has drained out of the t-case, it whines a little. To me that just means it is dry. I only drove it from one side of the garage to the other side, in order to have a better work area for what I anticipated would be an extensive and time consuming repair. As of right now, I am assuming that the internals are still intact. I’m keeping my fingers crossed.

I happen to know someone with cast iron brazing experience. I’ll reach out to him and gauge his response! Hopefully he is half as confident as the guy in your neck of the woods that would guarantee the repair.

Thanks again gentlemen! Keep the suggestions coming in as you think of them.

 

[Jbulach]

Wow. You all are a wealth of information. I appreciate the willingness to help.

Wheelspinner – I do have the yellow tags on the dash. I was competing in a truck pull contest. I admit that I reversed in low - shifting from high to low in the truck when under pressure is a challenge. Did the case crack as a result of the reversing, or as a result of the multiple truck pulls? I can’t answer that question.

Jbulach - The crack may have been a result of the NPT fitting being over tightened. I imagine that helped cause the crack, however, I don’t believe it cracked during the tightening. It was probably a combination of the pre-stress of over tightening combined with the extreme use during the truck pull (or reversing in low range).

Swamp Donkey – I drove it home after the truck pull and it drove just fine. Now that all of the gear oil has drained out of the t-case, it whines a little. To me that just means it is dry. I only drove it from one side of the garage to the other side, in order to have a better work area for what I anticipated would be an extensive and time consuming repair. As of right now, I am assuming that the internals are still intact. I’m keeping my fingers crossed.

I happen to know someone with cast iron brazing experience. I’ll reach out to him and gauge his response! Hopefully he is half as confident as the guy in your neck of the woods that would guarantee the repair.

Thanks again gentlemen! Keep the suggestions coming in as you think of them.

Was this a sled pull, or a truck tug-o-war? Any pictures/videos?


Did the oil pour out of the crack, just slow drip or somewhere in between?

Don't drive the truck without some oil, due to it uses a pump for lubrication!

I went out today and hit my case with a grinder and verified it is some type of iron and not cast steel.

I agree with Swamp Donkeys repair method all except I'm not a big fan of brazing cast, however that may be the best option, for an in truck repair. Especially, since I doubt the case will have much future stress on that crack other than from tightening the fitting. Another challenge is going to be sealing the crack all the way up to the edge of the threaded hole, without damaging the threads or welding the fitting in place, and don't forget about too much heat damaging seals and gaskets.
If it wasn't such a pain in the azz to clean properly each time I think I would start with a small bevel and an epoxy, just as a sealer. If that failed you could easily remove it all, bevel deeper then weld or braze. But getting this thing properly clean for any repair while in the truck is going to suck!

 

[floridastateo8]

Was this a sled pull, or a truck tug-o-war? Any pictures/videos?


Did the oil pour out of the crack, just slow drip or somewhere in between?

Don't drive the truck without some oil, due to it uses a pump for lubrication!

I went out today and hit my case with a grinder and verified it is some type of iron and not cast steel.

I agree with Swamp Donkeys repair method all except I'm not a big fan of brazing cast, however that may be the best option, for an in truck repair. Especially, since I doubt the case will have much future stress on that crack other than from tightening the fitting. Another challenge is going to be sealing the crack all the way up to the edge of the threaded hole, without damaging the threads or welding the fitting in place, and don't forget about too much heat damaging seals and gaskets.
If it wasn't such a pain in the azz to clean properly each time I think I would start with a small bevel and an epoxy, just as a sealer. If that failed you could easily remove it all, bevel deeper then weld or braze. But getting this thing properly clean for any repair while in the truck is going to suck!

It was a truck tug-o-war. I didn't get any pics / video worth sharing with the trucks back to back, but here is a pic of some of us lined up beside each other. I lost both pulls before the leak started. Next time I will be prepared (lower pressure in the tires and LOTS more weight - I was completely unweighted in hopes of competing in the DOT / street legal class).



The oil dripped slowly out of the t-case. If I had to guess, I would say it dripped about one quart per hour. This was probably accelerated during driving conditions, but it made the drive home 2 hours after leaking for 4 hours, with oil to spare.

Cleaning the cracked area wont be too horrible IMO. There is lots of room to access the affected area. I am thinking degreaser, then wire brush, then more degreaser, then wire brush, then drill ahead of the crack / grind a bevel through the crack. From there I can try the epoxy fix. I like the idea of seeing if that works before potentially overheating and damaging other components by attempting to weld or braze. And above all else, I like the in truck fix the most.

 

[Jericho]

Sorry otto correct 7018 rod , 7808 is jet engine oil. I am not big fan of brazing ,it is an introduction of a third material , many times brass, although many things can be used to seep into the microscopic surface of the cracked area and is more a filler and bonding agent than a MELDING material as welding is. if its not a structural weld it can surfice . But it works, can be a lost art. 7018 rod is made for welding cast iron. Nodular iron is a ductile mix of iron and usually magnesium, Very small amount ,it gives the iron workability, many cast cases are made from ductile (nodular iron) to give it increased resistence to cracking and making it more malable , Large plumbing and sewer pipes as well

 

[simp5782]

I want to know how you got outpulled by those trucks. An 855 truck should have no issue in low range dragging them around. They dont have the weight to put traction to the ground with the ag tires. An 809 series truck can full pull a sled in low range in 3rd gear. Heck they couldnt move the m923 with the parking brake up. Just sayin.

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[Swamp Donkey]

Whatever the case is made of, it's brittle, which is why it cracked in the first place. Brazing is recommended for non-structural repairs because the penetration is much better than welding. You also mitigate heat and stress problems since you aren't melting the native material. Preheating is still necessary though. The heat from welding can quickly exaggerate the problem or even cause more cracks to form.

The difficulty in cleaning is because the inside and outside of the area must be cleaned. The inside is difficult because you have oil that will run down the walls of the case once heat is applied. You'll need to preheat a larger area in preparation for the repair so make sure to heat this same area during cleaning.

The NPT fitting will also be an issue once the repair is made. I'd use High Strength Loctite instead of anything Teflon and only go slightly more than finger tight. The Loctite will seal and also keep the fitting from backing out. You'll stress the repair area if you tighten it completely.

If you decide to go the epoxy route you still need to stop drill that crack. You are in a good position right now for a repair. If that crack runs to the mating surface, that will be a game changer.

I enjoy watching those tug-of-wars.