4wd wheel engagement

2001 Chevy Silverado: When in 4wd only one (1) front and one (1) [opposite side] wheel engages for traction. Is this normal / typical? If not, what is wrong and how is it corrected?
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Your vehicle is equipped with a limited slip differential (see http://en.wikipedia.org/wiki/Limited_slip_differential ). That will cause a single wheel to spin independently of the opposite one. Not necessarily the best scenario for four wheeling (especially when said wheels are spinning in the mud). I had my first experience with this in an Isuzu Rodeo. Baffled me at first too until I looked at things.
Depending on the option package (I can't remember if this make/model/year had it included with the 4wd package) you may or may not have locking hubs. What that does is lock the vehicle's axle so that the LSD isn't working. Generally speaking, you only want to use this when A) low gear 4 wheeling, b) Stuck.
My brother had one of these, and I cna't remember it properly at the moment. I believe the ones with locking hubs were out on the wheel, not in the vehicle. So you had to get out and go to the wheels to lock the hubs.
Jody
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Thank you Jody. Makes perfect logic (not sense!!) when you are stuck in snow OVER ice on an incline in the mountains(I was glade I had a shovel to dig out with!) NO locking hubs on a 2001 - last 4x4 I had with locking hubs where you had to exit the vehicle to engage 4 wheel drive was a 1978 Ford (I know I just aged myself). Your answer is at least conforting. Thanks.
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richardprice wrote:

Unfortunately it is completely incorrect.
A standard differential, also called an "open" differential allows the two wheels on the axle to turn at different speeds, something that is essential for such things as turns where the outer wheel must travel a further distance than the inner wheel and thus must turn faster.
A limited slip differential has a mechanism with clutch packs / friction disks and is designed to allow the two wheels to turn at different speeds, but to limit how large that differential can be i.e. allowing for a limited amount of slip between the two.
A locking differential is similar to a limited slip, with the difference that they allow normal "open" type operation under typical conditions, but when the difference in speeds between the two wheels increases to a point where it activates the mechanism, the mechanism is able to fully lock the wheels together allowing no slip at all. When wheels speeds drop the locking differential normally unlocks and returns to normal "open" type operation.
A selectable locking differential is similar to a locking differential, with the difference being that the locking action is manually controlled by the driver (switch or lever), and not automatic based on wheel speed and slip.
None of these differential types has anything to do with locking hubs or center axle disconnect, which are both systems for reducing front drive train frictional losses when 4WD is not required, by allowing the front wheels to turn without turning the front drive shaft and transfer case output gears.
Locking hubs disconnect the wheels from the front drive axle, allowing them to freely turn without turning the front axles or drive shaft. A center axle disconnect is similar, but works in the center of the axle to disconnect each front wheel and it's axle shaft from the remainder of the front drive train.
A regular two wheel drive vehicle with "open" differentials under slippery conditions is really a one wheel drive vehicle, unfortunately driving only the wheel with the least traction due to the "open" differential action.
Add a limited slip differential to that two wheel drive vehicle and in slippery conditions the wheel with the least traction will slip, but the limited slip differential will insure that some of the drive power is still applied to the other wheel, therefore making it more likely you can continue moving. A locking differential in this situation insures that all of the drive power is applied to both wheels. A selectable locking differential does the same, only with manual control.
On a 4WD vehicle, another level of complexity is added as all of the above conditions still apply to the rear axle, but now power is also applied to the front axle, normally with an "open" differential up front since any sort of limited slip or locking differential up front significantly affects the vehicles steering control and is therefore rarely offered from the factory.
Since a 4WD vehicle has no differential action between the front and rear axles, the drive power is applied to both axles equally. Depending on the type of differential in the front and rear axles, you have anything from power applied to the one front and one rear wheel with the least traction, all the way up to power applied to all four wheels equally and a very difficult to maneuver vehicle that will move through most any conditions. Since most 4WD vehicles are part time, they handle normally when 4WD is not engaged.
An AWD vehicle adds a differential action between the front and rear axles which allows the drive power to be applied to all wheels all the time, resulting in a vehicle that handles well under slippery road conditions. This AWD usually does little to allow the vehicle to operate in off road conditions where 4WD vehicles are normally required.
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wrote:

Pete has it right. THe reason a open diff tends to spin RR and left front has to due with chassis torque reaction removing some load/weight for those wheels as power is applied. Open diffs can only balnce torque bewtween wheel and both axles get same torque, no more, no less. LSD and locker can send differenting amounts of torque to axles. SnoMan
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Whoa there Dude, Locking hubs do not lock the axles. They only lock the hubs to the axles so if the axle turns the wheels do too. And he may or may not have a LSD. Ck the codes on the inside of the glovebox door. Regards, JR

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