Slamming into 4wd

[dashhho]

05 B4000 4WD. auto hubs. 240k kms on truck. Has fresh fluid change about 20k kms ago

Recently I have noticed the tcase roughly activating into 4wd.

Once when I was trying to get unstuck in the snow I shifted into 4HI and waited about 10 seconds then gave it some gas..noticed only rear wheel spinning then bang it clicked in and the front wheels took off.

this happened to me once rolling down the road when I was shifting on the fly at around 30kph.

Any thoughts? Dont remember it ever doing this.

 

[franklin2]

No matter what type of 4wd system you have, it's not necessarily going to go into 4x4 when you hit the button. If you have ever had a manual system with the lever and manual hubs, you know when you lock the hubs in they do not necessarily lock in when you turn the button, things have to line up in there sometimes, so a little turning is required. Same with the transfer case lever, sometimes it will not go in, especially 4 low, unless you move the truck a little bit.

The best advice I can give is try to predict when you might need 4x4. Put it in 4x4 before you need it. If you get caught in 2wd and are stuck, put it in 4x4 and then gently give it gas till you feel it lock in. If you rev it up and spin and it suddenly locks in, that is when you break stuff.

 

[00t444e]

An 05 has full time hubs, not auto hubs.

 

[pjtoledo]

the tcase is not synchronized, the shifts don't occur until the gears/collars align.
if the parts are moving at different speeds something has to rapidly change speed.
when sitting still the gears still need to align, that may take a few seconds.

when shifting the tcase doesn't actually shift as soon as the switch is activated, rather the mechanism puts pressure
on a spring. when the gears/collar align then the spring pushes gears together.

shifting 2hi to 4hi should not be done under power, back of the gas a bit but not completely.

 

[wildbill23c]

It should also be noted that in extremely cold conditions the 4WD system may not engage immediately and it'll definitely bang into 4WD if your rear wheels are spinning when you hit the button or turn the knob the sudden loading of the drive train from the front end being in "neutral" or freewheeling will cause that sudden bang when it engages...different tire sizes and/or if your front and rear tires aren't worn evenly it'll cause this too.