M135 M211 2 speed transfer case mod

[DUUANE]

Hi everyone. I'm starting this thread to consolidate the information relating to converting our stock tcases to 2 speed units for those who wish to do so.
It looks like i will be able to lay my hands on a spare tcase locally here to do a bench test on.
If anyone has info on this conversion please post it here.
I have a couple of different options as far as machinists go so if it looks like a new shaft is in order i will look into that.
As soon as i get the spare case to the shop i will post up pics of whats in there and dissassembly. Hopefully we will be able to do this without a complete teardown of the tcase or even better do it in the frame.
Thanks for your time reading this and i look forward to hearing your experience.

Cheers.

 

[DUUANE]

Ok..after staring at the tm for a couple of hours unless im missing something it looks like the input shaft sliding gear is always splined to the input shaft. The input shaft sliding gear also continuiously engages the pto drive gear.
With the input shaft sliding gear engaged, the input shaft,input shaft drive gear and sliding gear all rotate as an assembly. They drive the front idler gear which is splined to the idler shaft clutch gear that is splined to the idler shaft rear gear that is keyed to the idler shaft.
It was suggested that by eliminating the bearing between the pto gear and idler clutch gear and shrinking a spacer in its place that somehow the power flow would change.
The front idler gear, clutch gear, and rear gear are all splined together and rotate as an assembly (idler shaft included) so as ive said unless im missing something if the pto drive gear was unable to rotate at a different speed than the idler shaft when the inpht shaft sliding gear was dissengaged you would add the reduction between the sliding gear and pto drive gear to drive the idler shaft and downstream gearing..but when you engaged the sliding gear with the input shaft drive gear you would effectively be in two gears at once now that the pto drive gear was a solid connection to the idler shaft clutch gear and its splined partners..and bad things would happen..

Am i seeing this right?

 

[DUUANE]

So..if the above is correct...the bearing eliminator/spacer would need to move the pto drive gear rearward in the case if possible and teeth on the input shaft drive gear would have to be shortened so the sliding gear was engaged with the input shaft gear or pto gear but never both .
That should get us there.. but i think low range would suffer durabillity issues.
If a cckw tcase is a straight bolt in that would be the way to play imho..

My kingdom for a road ranger...a 15 spd with 5 in the basement deep reduction

 

[USMC 00-08]

I have no experience to offer, but I have read where people have used a CCKW transfer case and transmission with success. These were old write ups with no pictures or video.

It will be neat to see what you come up with.

 

[Ashley P]

I hope I'm mechanically inclined (as a pro car mechanic), but unless I've got a very good diagram or preferably a unit to look (touch/feel), I'm probably not gonna grasp the power flow path.

The way I read the original post, the PTO output was sacrificed to get the other range. Was that your understanding?

 

[m1010plowboy]

Early Deuce Transfer Case 2 speed mod

This is a great discussion piece for me. I watched a couple of buddies tear one apart, buy $800 in new bearings and it's still joyfully pushing his 52 deuce around. Lots to learn.

Here is a breakdown of parts and pieces we can all put together with a 2 speed. Wouldn't that be nice! Great thread Duane, I'm all eyes.

 

[DUUANE]

Well im working from .pdf TM's i've downloaded and unfortunately my phone wont let me screen shot the diagrams..
I think that it is possible to make a 2 spd case from this, however..i dont think it would stand up to any real abuse. Pto gears generally are designed to transmit a %age of total engine torque not the full pull. It may survive for a while with a mild power plant and an auto. AT and MT series allisons tipically hit pretty hard and a cummins/stroke/duramax with a 5 or 6 speed manual would probably kill it in the driveway.
Yes Ashley P ..that was my understanding of what Rosco had posted. Maybe he can shed more light.
Sacrifice neutral and pto output for a reduction range. If my understanding is correct the pto output would still function but only in "low" range and the wheels would be driving at the same time.

Its my feeling that we all want to spend time running our equipment,not repairing failed modifications.
For the money the cckw route to a 2 spd seems like a wise investment. Install and maintain with regular service, wheel like a man with a plan, go home with the smile of Victory.

If the spare case comes my way ill take some pics and measurements . My MT 653DR trans has a 8:1 first gear and a modest small block makes almost double the torque of the 302. Will i need the 18:1 of the stock trans 1st low? I bet at some point i probably will but id rather have to winch out than swap a tcase to get my rig out of the bush.

I was excited about this too when it was mentioned..but im not sure about the viabillity.

 

[DUUANE]

I went back and re read rosco's post. I'm asking you's with winches..when you shift your tcase to neutral.
1. Do you shift to neutral then keep moving the lever to engage the pto gear?
2. Do you just disengage the drive to the wheels and pull another lever to engage the pto?
My truck doesnt have a winch or pto so i have no feel yet. Im trying to get a better idea of the shift procedure.

Thanks for your input and enlightenment.

 

[topo]

Lever to shift the transfer case its in gear or out of gear. It just disconnects power to drive the wheels so you can use the winch .
Lever to winch has neutral and cable on and cable off .

 

[gentrysgarage]

What I have found

HiYa Duuane,
I have been researching this also and never got anything concrete.."THIS IS WHAT I DID" sort of statements...always my friend's first cousin on his mother's side three times removed heard some one who did this...LOL! But I have to say I have seen alot of carnage of exploded 1000hp "Mud Truck" transfer cases and the weakness isn't the gears, if using M135 transfer cases (tc), it is the case itself. They do shatter but the gears looked fine, and one guy rebuilt his using his old gears. Back to the M135/CCKW strength there is a difference! They were only making the CCKW trucks strong enough to get to Berlin, they never planned on bring them back, all the better metals and heat treatment went into the airplanes.

 

[DUUANE]

Thanks Topo thats what i figured the situation was from looking at the TM's..gentrysgarage..yeah i understand..my CMP Ford is built to the same plan..the Bic lighter theory...
So where does that leave us in the discussion?
1. We have the question of what is the rato difference between input shaft drive gear/idler shaft driven gear Vs. Input shaft sliding gear/ pto drive gear.
2. There is the question of if we can modify the sliding gear so that it doesnt drive the pto gear when its engaging the input shaft drive gear.
3. Can we come up with a better way to permanently eliminate the pto drve gear bearing than a shrink fit.

 

[DUUANE]

Diagrams and parts views

Ok..i finally managed to figure out how to screenshot what we needed to illistrate this discussion. Here are the powerflow and part diagrams with some explanation from
TM 9-1819AC part 2 available courtesy of our excellent partners and hard working people at Steel Soldiers.

Happy reading

 

[rosco]

Hello
I have been away for a week or so. Also please understand that I am not computer literate & have a new computer & don't understand how to find what pictures I have yet. But my old 211's are still out in my bone yard. It seems that I've stirred up a rhubarb. It seems too, in my early statements, my caveat was that there were some bugs. I did the T-case work, about '75 or '76. Seems too, there was no neutral between Hi & Low range when I was done. In Plowboy's post #6, picture 2, assembly W, #4 bearing is the one that I replaced with a shrink fit spacer. Don't get it stuck in two gears.

The CCKW T-case is a bolt in fit. The only one I knew about, I blew the case on, trying to recover a wreck, over the side of the highway. I tied onto it with the winch, and backed over the other side of the highway hanging on the winch line..... The case broke, not the gears (as said appropriately).

I spent as much time staring inside the T-case as Duuane has, looking at the the pictures, & he has done a remarkable job with his insights. The best bet, is to keep the trucks stock with the automatic! I'll try to find the few old picture that I have, of the Old Days here, & post them up. Plowboy already suggested that, numerous years ago.

 

[DUUANE]

Thanks Rosco that would be a great help. I can see a way in my mind to create a safety so that it was dimensionally impossible to have the two engaged at the same time but until my spare tcase comes its all up in the air..in my head haha..
I just got intel on a 3 ton underlift on the cheap so i might have a small delay..

 

[DUUANE]

Update..my source here does not have a 135/211 tcase for me..on the upside he did have a bridge truck tcase that i needed for another project so..Yaaaay!
This thread will have to wait till i can lay hands on a spare unfortunately. I dont want to go messing up the one i have that works. The search is on...

 

[Ashley P]

Duuane, good luck in your quest. I remain curious and open to the cheapest/easiest way to achieve a lower range.

 

[DUUANE]

Ok so i guess the next step in this thread is asking if there is anyone in western Canada or the pacific north west that has a spare transfer case they'd be willing to sell me so we can move the dissection to the bench?
My wife is pretty near as awesome as they come..but itll be divorce court if another truck follows me home so i can have a transfer case to play with..

 

[m1010plowboy]

We should check with the Western Command boys and see if there is one closer to you first. Gizmo just bought SuperDave's supply so I can check if one is sitting on the ground Sunday. I have 3 donor trucks but don't see a window for me to remove one unless freeze up stays away until December. Stan L. on North Van is another vault of info so I'll poke a few guys on the coast before we meet in Kelowna for a transfer case...of a transfer case.

 

[DUUANE]

Excellent..thank you. I appreciate you asking around.

Cheers!

 

[m1010plowboy]

TC upgrade mod

I only have 2 in parts trucks and still think the Goat team has one apart on the ground so one way or another we'll get you set up. The e brake horns are broke on one of these but I know I saw several nos parts in Gizmo's new parts grab. If we don't find one out west you will be my cover for a west coast road trip.