Transfer case upgrade to a XM818

[mattgunguy]

Bout a month back my wife and I loaded up the 818 with relief supplies and took it down to Houston Texas. Heading home, high range decided to eat itself. 200 miles at 20mph sucked. Got him home though.
Fast forward a few weeks. Shelled out the motor in the deuce crew cab on the way to the KAMO rally. So now I need the 5ton to tow the deuce home.
Had the better half put the word out on some of the interweb group that we're in of a new transfer case.
Came up with a T-1138 within 300 miles of home.
2008 rebuild, that doesn't look it's ever been in a truck. The seller had a custom input flange made to fit the old 5ton shafts. Got it for $800 and $30 in gas.
Drove out today to pick it up, so that we can get this show on the road.
Yes, we hauled it home in a Prius. Can talk all ya want about a Prius, but I've pulled a deuce with it before.

 

[NDT]

Upgrade? Not sure about that as the 1138 tends to crack open like a nut when it feels like it. At least you will have positive front axle engagement. Let us know how it turns out. Oh and what is stencilled on your prius. Oh and thanks again for coming all the way down here to help us. Taking a break from flood repairs as we speak.

 

[mattgunguy]

I consider it an upgrade in terms of gearing, and not having a Sprag (spell check). I'll rebuild the T138 to have as a backup for this one.

I'm from Fort Worth, with family all over south Texas. My wife has family there as well. Don't care for any of them, nor they me. But it was still like helping family regardless.

I'm one of those rare people who actually likes Russians in general. Been endeavoring to learn the language better. The bump roughly translates to "Blue lives are important".

 

[74M35A2]

So that's in case you are ever pulled over by Russian police?

I want to see the Prius pull an M35a2.

T-case swap should be helpful to lower rpm and increase speed if your engine can pull it.

 

[mattgunguy]

YouTube prius pulling M35a2. Did a short one in the driveway once for proof.

 

[red]

According to others experience on the T1138 into a m809 series it will put you at about 1800rpm at 60mph if still on the 11x20"s. Not quite a direct bolt in but not a complex swap.

 

[mattgunguy]

Going by the experience of others who've done this before, primarily OPCOM. This is correct, for the 11.00x20. I've not seen any info anywhere pertaining to 14.00x20 tires. So I'm interested to see what I end up with.

Course in the end this truck will most likely get a Allison from a 939 as well. I know, don't do it. But I like different and for the life of me, I can't teach my wife to drive a standard. I've tried repeatedly.

 

[red]

Going by the experience of others who've done this before, primarily OPCOM. This is correct, for the 11.00x20. I've not seen any info anywhere pertaining to 14.00x20 tires. So I'm interested to see what I end up with.

Course in the end this truck will most likely get a Allison from a 939 as well. I know, don't do it. But I like different and for the life of me, I can't teach my wife to drive a standard. I've tried repeatedly.

About 1540rpm at 60mph with that setup. https://www.ringpinion.com/calculators/Calc_RPM.aspx

Not worth the cost to swap to an auto trans. Could sell the truck and go to a m939 series for cheaper than that. She can learn to drive a stick to. Friend of mine got a crash course one night being the DD for us on the way back from a club in my old 87 chevy 1 ton with the 4 speed and 454 engine. I was drunk to the point of talking like boomhauer again and he still learned hahaha.

 

[mattgunguy]

Putting an automatic in definitely ain't worth the the cost. Not by a mile. Just like doing something different. I've got an Allison at545 sitting in the yard that may get used instead. Haven't really put much time into that particular idea idea either way yet.

I'm know she can learn to drive a manual. She's not convinced of it. One of those very analytical people. Who wants to know why what does what when. That, I am not good with.

I learned a standard in 30 minutes on the way to work. It was figure it out, or get fired.

 

[74M35A2]

The reason you learned is the exact same reason she hasn't.

 

[mattgunguy]

Nothing tells you that you're a slob quite like having to take the seat out of your truck.
I swear I clean the trash out every few weeks. I thought so anyways. But on a plus note, found the coffee cup I've been looking for. For about two years now.

Old case is ready to come out tomorrow. Just sitting on the mounts. Wish I'd more than an hour to give to after work.
Stupid overtime. It's taxed out the check anyway.

 

[74M35A2]

Same schedule here. Working 50 a week, getting paid for 40, then doing 2 hours of algebra a night with my daughter, 6 days a week, because the teacher sucks. My 9 is not getting much attention right now.

 

[mattgunguy]

Wait. You get paid??? How do I manage that action?
I should have kept my butt a truck driver. This management thing sucks. 12 hour days for low pay & no appreciation. With 10 times the headaches & stress. Really didn't think that through.
We homeschool though. So on a decent day math is done before I get home. I'm saddled with history. Which I like. Having two 13 year old girls isn't fun though. Constant cat fight anyone...
One girl and the boy are at least interested in learning more about working on the trucks. Which definitely puts a smile on my face and makes break downs a little more worthwhile. Hopefully they'll help keep these trucks alive once I'm in the ground. We can only have faith.

 

[74M35A2]

I bought a turbocharged diesel 6x6 because I'm the only guy in the house.

Back to the t-case...

 

[mattgunguy]

Well, got the T138 out finally. The thing's a beast.

Decided to set it next to the T1138 and do a few comparison photos for those who've never had the opportunity to see the two types side by side. I never had.

The adapter for the jack shaft bolted right up. Had me worried. But seeing is believing.

Gonna try to at least get it hoisted up to place tomorrow. Gotta measure for spacers.

 

[mattgunguy]

Can anyone happen to know the size of the 4 bolts which hold the parking brake assembly to the T1138 case. They weren't in the box of parking brake parts.

 

[mattgunguy]

Well as it just so happens due to a twist of government procurement programs. Those 4 bolts I was asking about are the same as the bolts which hold the mounting bracket to the T138 transfer case. Which are 5/8-11 x 1-1/2". This also happens to be the same size as the studs for the mounting plate on the T1138 transfer case. That is once you tire of trying to get the demon studs out all nice and neat and reusable, and you just weld the nuts to said demon studs to back them out. Regrettably, I forgot to take pictures of this.

I have elected to relocate the vehicle mount on the passenger side. I wasn't happy with the case sitting in the truck at an angle.
My method of popping rivets is as thus: grind down the outside rivet head flush, center punch, drill the center out with a 1/4" bit about half way or so, take a 1/4" punch, place in drilled hole, and start hammering. The part will pop off before long.
This took me maybe 15 minutes to get the mount off.
To get the rivets out the rest of the way. I drill em the rest the way thru, put the part in the shop press, put the handy dandy 1/4" punch in the hole again and press out the rivets.

 

[simp5782]

Frame reemers and Mag drills work wonders as well. So does a plasma cutter on those cold rivets. Air hammers as well. once the head is gone its a 1 second punch out.

I dunno about this swap. I would have rather gone with a different ratio transmission since its all already in there and kept the T138 over the 1138. Just a lot tougher unit.

As far as your jackshaft companion flange that's common being able to swap it on. Same flange for the front output will fit there as well.

 

[mattgunguy]

Good choices as well. For some reason I have never owned an air compressor. Rules out the air hammer and plas for me. Maybe some day when I have a real garage.

I personally don't know which is a stronger case. Both have their virtues and draw backs. I personally am not a fan of the sprag set up in the 138. It's failed me on more than one occasion. I also do a lot highway driving, so having an overdrive case in addition to the trans is a benefit for me. Probably the main reason I went with the T1138. If not the only.

I really wish I would have gotten the T600 case I tried out a few years back to work right for me. Can't remember what the issue was with it unfortunately.

 

[simp5782]

The 1138 is not serviceable really so it has its drawbacks on that. It's major flaw is splitting the case as we all know. A T138 if something goes out you just pull a shaft here and get it replaced as they are available. I am actually going to pull my 1138 out and go over to an Oshkosh 55000A or a PLS transfer case. The T138 sprag is a pain but they do work right especially with the air override done.

Basically with the normal 5 speed and the 1138 you are the same gearing as speed as a normal M939 so 2100 with 14.00s is 68mph or around there. Then again 1400s are getting harder to find so you will want to go 395s which is 64mph @ 2200rpms or up to 1600s and bog her down.