I have known for a while that a "4x4" is not four wheel driven. Well, it is if all wheels have exactly the same amount of traction right? When does that ever happen in real world terrain:rolleyes: I have a couple questions as to how this system works in my 1995 6.5 diesel (I assume the system works identical to a 2003 duramax).

I ask because yesterday, we got our 2003 CC D/A 4x4 stuck in deep snow at the farm--front bumper was pushing it. It was set in 4HI and only 2 wheels were spinning, 1 front and 1 back. Had this experience in 4LO pulling RV through the mud earlier in the year. The G80 diff didn't seem to lock, and the front doesn't have any locking device correct?

To maximize traction, I would like to know the proper driving technique in the deep snow/mud to avoid getting stuck (or lessen the chance). You off-roaders could probably give me some pointers on technique.

About the G80 locker in 2wd only...everywhere I read it says 'will not engage above 20 mph'. So if im getting into deep snow/mud and i start spinning above 20 mph my G80 won't lock up right?? What if for example i was on glare ice going 40 mph and gave just enough throttle to slip the tires. Will only 1 back wheel spin in 2wd?

To start off from a stop on ice, under what conditions will it lock? It seems when I take off in the 95, it will have traction from rest until the point that i push it too far. Right then, the speedo will go from 10 to 30 mph in no time flat and the back end starts to go sideways. I don't feel or hear any kind of clunk telling me that it locked the axles. Has the G80 locked the axles at this point or was there not enough time for it to engage before going over the 20 mph locker limit? Next, if it does lock at say 10 mph on ice and you push the throttle to get both rear to spin way over 20 mph, does the locker unlock then and spin 1 wheel??

Then, once in a while just when the wheels/wheel start to slip in 2wd at low speed, I feel and hear a rapid banging coming from the rear end. To eliminate this, I either punch the throttle to induce more wild wheel spin or let right off the throttle. Is this the locker tryingto engage? The duramax does something similar under these conditions but it comes in the form of a violent bucking/shuddering of the whole truck (like driving over really bad wash-board on gravel roads). Feels real bad when it happens. Or is that just the back end hopping up and down because theres not enough weight in the back?

Last, in 4wd the front drive axles never lock together do they? Power always goes to the wheel with least traction right? Sorry for the long post and all the questions. Just looking for theory on the system. Thanks

Yes, 4wd is truely 4wd only under the best conditions (equal traction), and as you saw, 2wd (1 front / 1 rear) under the worst. It seems like in your snow condition the G80 should have locked to give you real 3wd (1 front / 2 rear), so it sounds like it isn't working properly.

The front differential is always "open" so no, it doesn't lock the 2 front wheels or have limited slip or anything.

When in a "situation", one trick is to apply various amount of light/medium pressure to the brakes and throttle. The braking resistance to the spinning wheels will transfer torque to the other wheels. You should be able to find the combination to get all wheels turning (and hopefully unstuck!!).

I've been stuck more in sand than snow (Southern California). The big trick there is to air down to 10-15 lbs of air in the tires. Are there other tricks for snow and deep mud? (I don't know, but I'd like to.)

The G80 doesn't know if you're in 2wd or 4wd. Others have described how it locks, or releases at some speed, or fails. You could search for those discussions (or arguments) but as always, don't believe everything you read on the Internet.

[On edit] I think the bucking/shuddering is the back end hopping and not the G80. My truck seems to do that, too (although only in 2wd so far for some reason). I haven't heard/felt the G80 BANG in the truck but I had an old Suburban that did it.

As Jake mentioned, try applying a little brake while you are on the go pedal. This will allow the rear tire with less traction to hold enough torque to engage the other tire. Sounds silly, but there is a required amount of torque needed to engage the gov-lok.

This can also help sometimes with open differentials (the front axle in our trucks) to engage the tire you want.

Also,

Being in Alberta with some severe snow, you may want to go with a skinny tall tire (235/85/16) or something similar. The small width cuts through the snow better, as you probably know. And the larger diamter helps keep the frame and body up out of the snow for less drag.

Thanks for the tips Josh and Jake. Never thought the brake could help 'balance' the power and help to lock the G80 but it makes sense.

Hi Folks, I am familiar with the posi-trac axles of the 70's and the gov-lok axles of the 80's. I have a 1998 C2500 and a 2004 Trailblazer, both equipped with the G80 option. I am told that the Trailblazer G80 is an Eaton locker. Is this so or is it a gov-lok design? My understanding is that a true locker is much better than the old posi-tracs but is this a locker or not? Also is the G80 in the C2500 the same design as the Trailblazer?

Hi Folks, I am familiar with the posi-trac axles of the 70's and the gov-lok axles of the 80's. I have a 1998 C2500 and a 2004 Trailblazer, both equipped with the G80 option. I am told that the Trailblazer G80 is an Eaton locker. Is this so or is it a gov-lok design? My understanding is that a true locker is much better than the old posi-tracs but is this a locker or not? Also is the G80 in the C2500 the same design as the Trailblazer?

G80 is a eaton piece. it uses a govener to aply clutches inthe diff carrier. and becomes in-effective above 20-25mph.

i an seriously looking at changing mine out too a true trac. though it is better than a posi or limite slip since there are no clutches to were out.
it is not a full blown locker like the legendary detroit locker.

here is a thread that i started
http://www.dieselplace.com/forum/showthread.php?t=126276

First off, the gov-loc's are not true lockers, there more like a posi. They work off the torque applied to them thru the axles from traction from the tires. If your on dry pavement and either have enough power to spin the tires, or hold the brake, there is enough torque applied to it to cause the axles to become sorta one, and you'll lay two nice black patches. If your on ice, where you NEVER want both rear tires to spin on pavement, or mud, there is not enough torque applied to the diff thru the axles to force both tires to spin. The shuddering is your leaf springs wraping from the torque causeing wheel hop.

Now for tires, BFG all-terrians are the #1 snow tire out there, i plowed snow in Iowa for six years and never got stuck, with both diffs open. As far as the comment made about skinny tires... If all you have is 6" of soft powder, with gravel or frozen dirt beneth, something with traction, then maybe. But there is no substitute for flotation. The wider the tire and lower the psi the better. espically since you said you were plowing the snow with the front bumper. Think of how a snowmobile floats on the snow because of the 1x4' track on the ground. Or how if you lay down on thin ice it will stop cracking, hopefully anyway. :)

In my opinion, posi's are only good for a dry pavement enviroment. When it's slick a high percentage posi "some posi's engage easier then others" can down right get you in trouble in less then a heartbeat, and the shorter the wheelbase the worse it is. though they are fun in the wallmart parking lot. I have two eaton e-lockers in my 1997 TJ, at a push of a button they go from fully opened to fully locked, in 4wd as long as one tire is on the ground i'm still moving. And yes sometimes that does happen :).