I own a 2002 Chevy Silverado 4x4 Ext. Cab and was wondering why when the 4wd is engaged it seams as if the the rear end is acting like it has a "posi- trac" or "locker"? It is very noticable on hard surfaces like hard-pack the rear inside tire of a turn "skips" and digs up dirt. When not in 4wd, and trying to spin the tires only one tire spins, usually the right rear.
When you are in 4x4 on a hard surface, the rear axle has a shorter rolling radius than front axle but both are being driven at same speed. Being that there is no differentail between two axle the rear axle has to slip because of torque build up. It will slip first because unless rear is loaded, the front is heavier than rear. This is why you are not supposed to use 4x4 on hard surfaces because there has to be some slippage.
----------------- TheSnoMan.com
How can the front and rear axle have different "rolling radius" when the truck has a matching set of the same size tires, and the same OEM gears front and rear?
Very simple, the axles do not follow same path in a turn. The front axle takes a longer wider arc than rear axle in a turn. If you doubt me, drive on a dirt surface or pavement with wet tires that will leave track on dry surface and measure the length of the tracks in a turn. The rear track is shorter. In the 70's they made trucks with Full Time
4x4 that had a differentail between front and rear axle and allowed 4x4 operation without bind on hard surfaces. It died out in 80's because it used a bit more fuel.----------------- TheSnoMan.com
Yep, and using 4X4 on a high traction surface is a great way to find any weak parts in the drive line.... The vehicle will start to "crow hop" and then BANG as something lets go...
Thankyou, I just needed that last little bit of info to make it clear to me. Thanks
It's explained in your owner's manual.
Al
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