OBS 4L80e AWD
 

I currently have a 99 2dr Tahoe already swapped with a 4l80e and the autotrac transfercase. I wanna install a NP149 for its AWD. I know that there’s a custom 32 spline input shaft being built out there but I came across GM part number 12386258. It’s a 32 spline input shaft made for the NP246. Does anyone know iOS interchangeable with the NP149 from a SS

Dont quote me but i think Ive heard that the transfer case from the NNBS AWD trucks like the Denali's and the Escalades, bolts right up to the 4L80.
In other words the AWD transfer case from the 6L80, dont quote me though.

I was thinking of this same thing yesterday, since im looking to build an AWD OBS next.

Seems like only the np149 will work being it ises a Viscous coupling to split the power 68% 32%. When it senses slip it can divide the power either front or back up to 100%. All other transfer cases use the ABS system to work. The NP149 only camenwith 4l60e’s in Sierra Denali C3 and Silverado SS. The only way to get it to work with an4l80 is to change the input shaft on transfer case to 32 spline or change output on 4l80 to much weaker 4l60 size which defeats the purpose of having a 4l80. After reading seems like ONLY option is custom input shaft

Yeah im aware of the input shaft method, as I've built an SS with a 4L80 before.
Ive also seen a few AWD trucks built around town, who swear they have a 6L80 TC on a 4L80 trans, as the 6L80 TC is 32 spline as well. I didnt know the 6L80 TC worked off the ABS system, guess you learn something new everyday.
Good luck buddy

the nnbs awd transfer case (bw4485) bolts up to a 4l80 with a 4l80 tcase adapter. same spline. there is no viscous coupling in it though so it acts like an open differential.
when i had mine apart the planetaries are stamped "40/60" it's all mechanical. the ABS/stabilitrack is used to control wheel spin - worthless if youre trying to race with it since it you can tune out most of the TM that gets pulled but it still wants to apply the brake to the spinning wheel. pulling the ABS fuse will keep it from applying brake.

never used one but id imagine the np149 would be a much better transfer case to use, im not particularly attached to my nnbs case it just hasnt died, I have thrown a lot of weight over the front, adjustable coilovers, when it starts becoming the limiting factor ill do something with it

The NVG 149 is the ticket. Or NP149 depending. I even bought a spare for my truck just in case. It’s a great Tcase.

How much HP are you running. Do you get front wheel spin when nailing it at the line?

when I get wheel spin it’s all 4, never had just the front spin. As far as hp, never Had it on a dyno but based on mph and weight I am around 900-950 to the wheels.

What front differential are you running. I have a 9.25 2500 front diff in my obs currently. I also jus picked up a awd front diff from a 2002 Denali. If I keep my 2500 diff do I just leave it locked in 4wd with the NP149 case or should i swap it out for the awd diff. Is the awd 8.25 diff strong enough Only looking for 700hp

I have the stock front diff that was in my Denali.

I read this thread hoping to hear glowing reviews on the NV149 as I just picked up a Sierra Denali. The BW case in my Yukon Denali left me stranded MANY times in the snow and I just went to 4WD when I swapped to the NV4500 just to not deal with the problems of the BW448x cases.

Impressive it holds up to 900hp

Performance wise supposedly the 149 is better because it’s AWD is mechanical with a viscous coupling as opposed to borg Warner that uses your abs to divide power. As far as snow I am in the north east and my 06 Escalade never real gave me any problems.

The NVG149 is a great tcase for performance.

The ABS has a very limited ability to transfer power around. Plus it eats up your brakes and kills power. When I swapped to the 4WD case my offroad and snow handling abilities went up 10 fold. Especially if you tow trailers offroad.

If you want to stay 9.25 up front grab the passenger side tube of the 9.25 from under an H2: they are awd and will eliminate CAD and some bearings in the passenger side

So if I stay 9.25 and swap h2 axle tube I will just cap the hole where the actuator is and the 9.25 is technically a awd 9.25 diff. Do I need to activate 4wd before I swap out the tubes

After looking further into the H2 axle tube swap I don’t think it will work. Mounting tabs are completely different.
https://cimg5.ibsrv.net/gimg/www.per...bb062aea08.png
Hummer H2 awd
https://cimg6.ibsrv.net/gimg/www.per...126098f400.png
9.25 4wd

Well shoot, I didn't know they changed that much over the years!

all is not lost yet. The passenger axle for the Hummer is solid, no CAD. You could buy one, press out the axle and put it in your tube. Remove and cover the actuator hole and you have a Gen1 AWD 9.25. Would be a good
time to rebearing/reseal your diff too

https://fortwayneclutch.com/product/...-sku-40057073/

This??

on another note the fork part of #11 does it go between #7 and #8 or between #8 and #9

https://cimg9.ibsrv.net/gimg/www.per...9aadb69126.png


Thanks

Yes that's the shaft

as for the fork it's really hard to get that wrong. The fork rides on #8 and slides 8 back and forth to engage or disengage the passenger axle. You would have had a hard time getting that back together if you did it wrong. Could have happened tho

So I picked up a nice AWD Front diff from a Escalade. Can I swap over awd 8.25 diff with the solid passenger side axle. and keep my autotrac NP246 transfercase in 2wd until I get my np149 input shaft

I guess that would be fine. Swapping to the smaller diff when you already have the bigger seems like a step backward, but if the ratios match and youre happy; have at it

the 246 has a clutch on the front shaft, it should be fine but I wouldnt make this a permanent build, I think you will eventually smoke that clutch by forcing it to spin with the front shaft.

Seen a bunch of people with awd front diff 1000whp so will be plenty. I dont trust the custom made cv axle in my truck. When I bought it the last owner had to shorten the cv axles 3/4 in and sleeved and welded it because of the 2500 diff swap. I Snapped it the other day at the sleeve because my 2500 front diff CAD is locked in 4wd. Also have a problem lowering it being the 2500 diff is 2in wider so the stub shaft plate bolts that go to the cv axle is rubbing a little after I lowered it. Since it’s not a 4x4 mid slinger any longer 9.25 has to go. I will remove front Drive Shaft and leave the TRansfer case in 2wd for now so it don’t burn up