On my '99 F150, I was replacing the front U-joints and with the front end up in the air, the driveshaft would turn the axle and the front tires would move. Shouldn't the driveshaft be disengaged from the axle when not in 4x4? How do I go about troubleshooting the problem? Thanks.

 

Nope, they are always locked in. When you put it in 4 wheel drive it will engage the transfer case motor and engage the front differential. No need to worry.

-Matt

 

So basically, the driveshaft from the front axle to the transfer case always turns when moving? I guess I thought it didn't until the transfer case was locked in.

 

Nope. From what I understand (and someone correct me if I am wrong) the front tires spin when driving which turns the cv-joints and shafts into the front differential ALL THE TIME. The driveshaft from the transfer case to the front differential does not move (much).

The you lock it in 4 wheel drive by turning the switch and the shift motor will engage the 4 wheel drive at the transfer case and by vaccum it will engage the front differential so that everything is spinning together.

Clear as mud?

-Matt

 

That is how I thought it should be to. But with the front end up, if I grab the front driveshaft and spin it, the front tires will turn. The shaft is not "freewheeling". If anything, it seems that the axle is not disengaging.

 

with the 4x4 disengaged the front driveshaft shoult turn free not spinning front wheels check your vacumn linr which disengages the front hubs, it is up by the battery.

 

lift all 4 tires and put it in gear, i know when im in 4wd i can feel it