mrpeterclark
Full Access Member
Thought I would post a bit about my AWD to 4WD conversion on my 2007 GMC Yukon XL Denali. I like the AWD for snow driving, traction, etc., but wanted selectable 4 LO and being able to have 2WD for a little more daily, highway efficiency and donuts
One other major downside of the AWD tcase is that when you break a cv axle, you are immobile because the tcase is like an open differential. All the power goes to the spinning axle but no traction control (brakes) to stop the spin.
Transfer Case is a custom reman NP261 from National Differential in Colorado Springs. I had it built as an NP261XHD - heavier duty chain and components as I’m running a 525 crank HP 6.2L. This tcase utilizes the same input and output shafts to mate to the 6L80 and drive shafts without modification. Also, a manual unit is plug and play since the Denali has no TCCM or wiring and doesn’t communicate anything to the ECM, BCM or TCM. Trying to add the necessary wiring and a TCCM to use an electronic selectable tcase would be a major undertaking.
I used a JB Fab slim shifter mounted to the side of the console.
Interior is in need of a deep clean after the season of camping and road trips.
I didn’t document this well, but the cable makes a loop up and back down to come through the side of the hump pointing back toward the tcase. It is zip tied to the metal brace behind that plastic cover. I was able to fold the top of the carpet back to expose the joint in the insulation without having to pull the console and carpet which was nice. I lifted the upper section of padding slightly and drilled a pilot hole to make sure the location would work. Then I drilled a 1-1/2” hole with a hole saw to fit the 1-1/2 grommet with a hole that fit the cable that I found at the auto parts store. I couldn’t find an angled grommet. I drilled through the small hole in the grommet at an angle to make the hole angled so the cable could slice through the grommet at an angle. There wasn’t a way to put the cable through perpendicular to the floor.
I have a stock front differential. This works fine, it just means the internals are always rotating just not being driven by the tcase in 2wd. Had I made this decision earlier, I would have used a tcase with a center axle disconnect when I swapped transfer cases and installed 4.56 gears the year before. It’s not that big of a deal though. I talked to an Escalade owner that did something similar. He explained that it is just simple 12v wiring to the CAD and he just has it on an on/ off switch which he turns off when in 2WD. The manual trucks engage the CAD via a switch at the lever. Just make sure it’s not something you might accidentally turn on at speed. Bonus points: this would also give you 2LO should you wish to pull without straining the front or twisting on CV axles.
This first snow didn’t really hang around long enough to get a good 4wd test yet, but so far I’m liking it and looking forward to having 4 LO for steeper sections.
One other major downside of the AWD tcase is that when you break a cv axle, you are immobile because the tcase is like an open differential. All the power goes to the spinning axle but no traction control (brakes) to stop the spin.
Transfer Case is a custom reman NP261 from National Differential in Colorado Springs. I had it built as an NP261XHD - heavier duty chain and components as I’m running a 525 crank HP 6.2L. This tcase utilizes the same input and output shafts to mate to the 6L80 and drive shafts without modification. Also, a manual unit is plug and play since the Denali has no TCCM or wiring and doesn’t communicate anything to the ECM, BCM or TCM. Trying to add the necessary wiring and a TCCM to use an electronic selectable tcase would be a major undertaking.
I used a JB Fab slim shifter mounted to the side of the console.
Interior is in need of a deep clean after the season of camping and road trips.
I didn’t document this well, but the cable makes a loop up and back down to come through the side of the hump pointing back toward the tcase. It is zip tied to the metal brace behind that plastic cover. I was able to fold the top of the carpet back to expose the joint in the insulation without having to pull the console and carpet which was nice. I lifted the upper section of padding slightly and drilled a pilot hole to make sure the location would work. Then I drilled a 1-1/2” hole with a hole saw to fit the 1-1/2 grommet with a hole that fit the cable that I found at the auto parts store. I couldn’t find an angled grommet. I drilled through the small hole in the grommet at an angle to make the hole angled so the cable could slice through the grommet at an angle. There wasn’t a way to put the cable through perpendicular to the floor.
I have a stock front differential. This works fine, it just means the internals are always rotating just not being driven by the tcase in 2wd. Had I made this decision earlier, I would have used a tcase with a center axle disconnect when I swapped transfer cases and installed 4.56 gears the year before. It’s not that big of a deal though. I talked to an Escalade owner that did something similar. He explained that it is just simple 12v wiring to the CAD and he just has it on an on/ off switch which he turns off when in 2WD. The manual trucks engage the CAD via a switch at the lever. Just make sure it’s not something you might accidentally turn on at speed. Bonus points: this would also give you 2LO should you wish to pull without straining the front or twisting on CV axles.
This first snow didn’t really hang around long enough to get a good 4wd test yet, but so far I’m liking it and looking forward to having 4 LO for steeper sections.
