Mighty Whitey

I've read, and seen numerous people having problems with the front axle disconnect not doing it's job, and leaving someone in a bind when they need 4wd.

seems like the transfer case always seems to do the right thing, and shift (powering the front driveshaft) but without the axle disconnect working, it free-spins, like a peg-leg rearend with one axle broke.

now, here's my delimma:

my '02 z-71 has the NVG246 autotrac, pushbutton 4wd BS. when I have it in 2wd (not auto 4wd) I climb under the truck, and the front driveshaft will not turn if I spin it by hand. if I push the 4wd button, the transfer case locks in, and the same thing happens: no free-spin of the front driveshaft. shifting back in the 2wd, results in the same thing. if I'm in a bind and need 4wd, the front tires do pull, so I know it's locked in right.

is it possible for the front axle disconnect to be stuck "locked in" as opposed to being stuck open, like everyone else's seems to?
I recently put on a set of 285's, and noticed the mileage has went to **** (from an easy 15mpg, to a best of 13mpg) very shortly after. I was thinking the tires dropped it some, but not 2mpg (and I did use a 1.03 correction factor to get the actual mileage driven, going from a 265 to a 285)

viciousknid

iTrader: (8)

I'd say it's easily possible to be stuck in. Have you tried unbolting the actuator from the front axle, pull the truck forward a ways to make sure it unlocked, and then seeing if you get free spin on the driveline? That should tell you if it's the actuator or not.
Also you can leave the actuator plugged in and have someone hit the buttons and see if it moves in and out like it should.

On my old 89 It was a vacuum actuator and I ended up hooking up a Posi-Lock cable cuz the vacuum lines where all messed up. Kinda wish i would just found an electric actuator.

Mighty Whitey

I'm not 100% sure how the actuator comes off the front axle. I was looking at it on my lunch break friday at work, and didn't really get a lot of time to mess with it to be honest.


does the actuator just un-screw out of the iron axle tube like the C/K trucks do? or does it have some hidden bolts somewhere that I can't see?


I've got a 4x4 posi-lock sitting in the garage, but I'm not gonna gom-up a new truck like this with some pre-historic PTO cable in the cab. I'll spend the cabbage on the right part for it..

viciousknid

iTrader: (8)

I agree. That's why I wish i'da just used an Electric actuator from a 90's blazer.

It actually looks like it either pushes in and turns, or like there's a c-clip. I don't notice any threads an any of the replacements. I'll see if I can find something that says.
Hopefully someone will post up that knows for sure.

kbracing96

iTrader: (26)

With the autotrac, the front drive shaft is ALWAYS engaged in the transfercase, and you can never turn it by hand, even in 2wd.

Mighty Whitey

that seems to be the same thing I'm hearing over on another board. if this is so (which it seems to be) why is there a disconnect actuator on the front end? the H2 hummers don't have one at all (abeit, they are full-time 4wd)

would there be any MPG increase if this were to be disconnect somehow? if I had a lever-shift transfer case (still the NV241??) it wouldn't turn, atleast my '94 doesn't.

oh well, guess this is just part of the modernization of the american pickup truck. what happened to the days of lever shifted transfer cases, and 1/2 turn manual locking hubs???

sharpshooter

iTrader: (10)

My 99 front shaft is always engaged but my friends 04 autotrac's front shaft would free spin in 2wd.Did gm make changes?I've read that the t-cases[autotrac]clutch pack is always about 5% engaged[no free spin on front shaft] but did they do away with the 5% on the newer ones?

KevinF56

iTrader: (9)

i have the manual 4wd lever on the floor in my 2004 silverado, and when in 2wd my front drive shaft does not spin, only when i shift it into 4wd. i know this because my front shaft rubs my y-pipe

sharpshooter

iTrader: (10)

KevinF56 you don't have autotrac right?