Swap from AWD to 4X4 two speed TC

[SpareParts]

As far as i know this only applies to 07-13 AWD Escalades and Yukon's.
There may be other ways to do this but this is how im doing it.
Escalade's and Yukon's do not have a Transfer Case Control Module and nothing electrical is attached to the TC
You will also need to swap the front diff to a 4X4 diff so you can select 4X4 or 2WD
It's pretty easy to do mechanically.
The TC has to be a NP261HD and it has to come from behind a 4L80E as it has 32 spline output shaft and is the same bolt pattern, shaft depth as the AWD TC. LD (27 spline) XHD (29 spline) will not work so count the splines to be sure.
Not all HD TC's will be stamped HD.
Use your original drive lines.
I pretty much rebuilt my 261 with new bearings, forks, chain, range gear, aluminum rear case half, seals and case saver



To support the transmission for cross member removal GM provided a place on each side of the transmission you can hook a ratchet strap to.



Swapping them is easy. I swapped mine in 3 hours by my self.
It's not that heavy so just get under it somehow and bench press it into place.



1 challenging thing is the nut at the very top of the TC adaptor. There is not enough room to get a ratchet or full size wrench on it.
I got lucky and had a small old worn out 9/16 wrench that would fit good enough to get the nut off and on.



At this point i can drive in 2WD
Tomorrow ill post about the electrical. I'm pretty confident i have that figured out.

 

[donjetman]

@SpareParts
Would this TC swap, and maybe a Remco driveshaft disconnect, allow me to tow my 07 Yukon Denali 4-down?

 

[randeez]

i dont know if the electronically shifted 261 lets you select a neutral position on the case, its there but only because TC wants separation before going from 4hi to 4lo iirc. a manually shifted (stick on the floor) 261 you can put it in neutral - theres currently a manually shifted 261 in my yukon. i used the factory sandwich plates to bring stick thru the floor and bent the lever to come out just below the console

 

[SpareParts]

The TC does have a neutral position and the front would be unlocked. I don't know but that might be all you need?
With the TC in neutral the internal oil pump would still be working when moving oiling the internals but nothing else would be connected.

 

[SpareParts]

i dont know if the electronically shifted 261 lets you select a neutral position on the case, its there but only because TC wants separation before going from 4hi to 4lo iirc. a manually shifted (stick on the floor) 261 you can put it in neutral - theres currently a manually shifted 261 in my yukon. i used the factory sandwich plates to bring stick thru the floor and bent the lever to come out just below the console

Could you post a few pics of the shifter installed?
I'll be installing that today and knowing the location would help a lot!
Thanks

 

[randeez]

when i get home i can, not much to see cause of carpet and console covers everything up. with the factory sandwich plates its obvious where it goes, theyre contoured to the floor pan/trans tunnel (for the most part), so just need to line it up mark where to cut for the shaft to come thru and has indentations for the bolt holes to be drilled out in the floor pan also

 

[SpareParts]

@randeez
Nice.
I did not think the floor pan had the mounting point marked out on the 07-13's
Up and down is pretty easy. Forward and back is the hard part.
Did you swap the front axle also?

 

[strutaeng]

Very cool!

 

[mikez71]

How do you activate 4-lo transmission shift schedule?

 

[SpareParts]

Since the AWD does not use or even have a VSS and reads speed from wheel speed it should not need to use a 4x4 shift mode.
But looking at the ECU it does have a 4x4 mode in it already, so a ground wire might be needed to be run from the TC mode switch to the ECU.

 

[SpareParts]

To wire it all together so is all works as it should.
On the front actuator:
Wire B: is a ground and would go to an indicator light for 4 low and 4 high. The light would have 12V with key on.
Wire E: Ground
Wire C: Switched 12V Positive
Wire A to transfer case wire C.



Transfer case range plug.
Wire A: Ground
Wire C: to wire C from the actuator.
Wire B: goes to the ECU. Plug C1, Pin 2. It is a gray/black wire you might already have it.



Test all connections with key on engine off trans in neutral. You should hear the actuator move going in and out of 4 low and 4 high.

 

[SpareParts]

For the shifter i had no idea where to start and make the hole. My guess was about an inch to far back so i had to make the hole a little to big so i could get the linkage to line up.
I also did not use the plate that goes on the outside as i did not get it or lost it. My shifter is mounted solid with 3 bolts/nuts and thick fender washers on the outside.



The edge of the shifter ended up being 6 inches from the circled in red bolt.



After bending the shifter out a little bit it ended up being in the perfect spot. Easy to shift and not even close to touching my leg.

 

[SpareParts]

Test drive time and i have all the gears Everything feels solid.
Really no noticeable difference between 2wd and 4 high both feel the same driving. Turning sharp on pavement you will notice it though.
4low i don't really remember how they should shift but the trans shifts through all the gears and at 20mph (gps)(70mph speedo) you are in 6th gear at 2k rpm and shifting is slightly jerky.
I will try hooking up the ECU in a week or two and see if that makes a difference but i need to get a pin first, but it's not bad the way it is. More curious.

 

[j91z28d1]

@SpareParts
Would this TC swap, and maybe a Remco driveshaft disconnect, allow me to tow my 07 Yukon Denali 4-down?

if you know what vehicle make and year the tc comes from, I think you could download the owners manaul from the gm website and look what it says. mine specifically says I can flat tow mine in N if I want to.

I'd be surprised if you needed a drive shaft disconnect.

 

[SpareParts]

From everything i have read you can flat tow with a NP261 in neutral, Trans in park and a 4x4 front diff. With the AWD front diff it would tear up stuff im sure.

 

[donjetman]

so no one knows.

Back in the early 80s I had a 75ish Chevy Blazer 4x4 w/SBC & Automatic with full time awd with 2 speed TC with neutral and manual shifter thru/on the trans tunnel.

 

[89Suburban]

so no one knows.

Back in the early 80s I had a 75ish Chevy Blazer 4x4 w/SBC & Automatic with full time awd with 2 speed TC with neutral and manual shifter thru/on the trans tunnel.

Same era Dodge trucks and Ramchargers had the same setup.

 

[SpareParts]

Tried hooking up pin 2 on the ecu to the transfer case today and it seems to do nothing when grounded.
I'm not sure at all if the ecu switches to 4x4 mode and i do not know how to tell.
The ecu has X, Y, Z mode and right now all modes are set to X. All modes are also set to the same settings.
Plan is to read my Avalanche with HP Tuners and see if 4WD mode is set different and if it is copy that mode from the avalanche to my ecu and try it again.

 

[SpareParts]

Pretty sure i need to create a new pattern in the ECU for 4X4 mode.
I posted the question on HP Tuners forum.

 

[SpareParts]

Making progress a little at a time.
Using HP Tuners VCM Scanner i can see that when i shift to 4Lo the TCM shows 4WD Low Active.
I think i need to find something as close to 2007 that has a 6L80E that is 4X4 to copy over the 4Lo shift pattern. I have no idea really so waiting for help on the HP Tuners forum.