I am new to this truck (just bought it 2 months ago) and really like how it runs and looks, 2002 F250 Super Duty gasoline 4x4 Lariat. Yesterday I was cleaning my yard and wanted to remove a small tree (7-8ft tall), I said let's try my truck to pull it off, hooked rear hitch to tree using a rope, using 2WD, and this happened... the rear passenger tire start to dig a hole on the grass, the driver rear wheel was not even moving, only the rear passenger wheel was spinning, I switched to 4WD, but did not help, rear passenger wheel kept spinning... Please help me to understand how this truck works... on 2WD the 2 rear wheels are supposed to have traction or spin, right? I am sorry if I don't make sense. Thanks

 

An open differential is designed to apply power to the least traction wheel, this is designed to prevent a spin on ice or other smooth low traction situation.

Do you have a shift lever or switch for 4wd? Chances are that the transfer case didn't shift into gear because the truck wasn't moving, this is to prevent bind in the case and prevent damage from slamming gears.

 

First, you have an open differential. Should you find yourself in this situation again, slowly apply the brakes lightly while the rear wheel is spinning. It will "lock up" the differential and hopefully allow you to drive out.

Second, did anything happen when you switched to 4 wheel drive, beside one back tire spinning? Do you have Electronic Shift On the Fly?

 

My truck has a SWITCH for 4WD.

I don't think that my truck has Electronic Shift On the Fly.
Thanks

 

If it has a switch it is ESOF. It won't shift normally while the truck is stationary, regardless of the rear end spinning.

 

Yup, you have Electronic Shift On the Fly...or ESOF.

Did the 4 wheel drive light comed on?

 

Yes, the 4 wheel drive light came on.
I guess next time, I should switch to 4WD before trying to do something like that? also, under normal conditions...2WD, the 2 rear wheels have traction or only the passenger rear wheel?

 

Normally, if they both have traction, they both receive torque, however as soon as one looses traction, it gets all the torque.

 

In 2wd it is normal to see only 1 wheel spinning, unless you have a limited slip differential. Obviously you don't.

The wheel that has the LEAST amount of traction will be the one that slips.

 

An open differential will send power to the wheel that is spinning the fastest. Normally this would be the outside wheel when you go around a corner. When you get into a slippery situation, the open differential can (as you just found out) send the power to the wheel with the least traction. Applying the brakes lightly would have slowed the wheel down and sent power to the other rear wheel.

It sounds like your transfer case shifted (you got the 4x4 light) now you need to find out if your hubs are locking.

 

Thanks very much, now I know a little bit more how this thing works...last time when I was stucked on sand, I switched to 4WD, the 4 wheels got traction and the truck was able to move out from the hole... may be I did something wrong this last time when I switched to 4WD and hubs did not lock up. Thanks

 

redford, so if i read ur post correctly, while the wheels spinng (meaning u applying the gas) u apply the brakes slowly and this should get ur other tire to hook making both tires turn? am i right?

 

Right, this confuses the cones in the rear differential and causes them to apply power to both sides equally. Its a limited use deal, the differential is not designed to work this way.

 

JMO but I would drop the tire pressure to prevent myselft from getting stuck. I think too many people are driving these trucks around with 75-80 psi in the rear and never tow or haul anything. I have droped my duals down to 20 psi to prevent getting stuck and my fronts to 15.

I know this does not answere the OP's ?'s but traction helps in his situation.

 

See if you can find "differentials" on howstuffworks.com to get a better understanding of how this works. If you have an open differential only one wheel will be getting power when there is a low traction issue. So, your 4x4 is really only a 2 wheel drive (one front and one rear) when you're in a low traction situation.