Clunking in 4WD when turned full lock?

[KentC]

I just noticed this problem this week, when I turn full lock in 4WD the front end seems to be binding up and banging when it releases, it does not do this when in 2WD. Is this a problem with the trasfer case or the Axles? it seems if it was the axles or CV shafts that it should do it in both 2wd and 4wd.

 

[RangerX]

Are you talking about when you're on pavement, or in dirt?

 

[tipdrill]

I am going to assume this is on dry pavement.

Turning on dry pavement while in 4wd should be avoided. When you turn the wheels, they roll at different speeds. So if you turn with the front wheels engaged something has to give.

 

[KentC]

I have only tried it on dry pavement, is this a common problem??

 

[steventadams]

the clunking isnt a problem... its supposed to happen, kinda. when you turn 4x4 on it locks the hubs which locks the axles. When the axles are locked both wheels turn at the same rate and physics shows us that one wheel must travel slower than the other in a turn at full lock. Because you're trying to make the wheels turn at different rates when they are locked to turn at the same rate you have things getting stuck and releasing and getting stuck and releasing and its not good...
At least that what I've gathered from my limited knowledge of how hubs work and what i learned in physics last year... Someone feel free to correct me if its wrong.

 

[KentC]

Thanks guys!! now that it pointed out to me it makes alot of sense, will just avoid in the future

 

[steventadams]

thats why we're here. welcome to the explorer encyclopedia...

 

[IZwack]

I swear Ford needs to put a sticker on 4wd vehicles telling owners not to engage 4wd on dry pavement.

 

[steventadams]

why exactly cant you do the 4x4 on dry pavement. i know you shouldnt turn with it on but is it bad to go straight too?

 

[IZwack]

why exactly cant you do the 4x4 on dry pavement. i know you shouldnt turn with it on but is it bad to go straight too?

You're right, going straight doesnt present a problem because at that point the drivetrain doesnt bind as much, but it is unlikely that one needs to go only straight.

If you were to do 4wd on pavement for a long time, the transfer case's clutch will wear out very quickly everytime the vehicle makes a turn and there is a good chance the transfer case's chain will break.

 

[steventadams]

and its better to use the 4x4 on loose ground because the dirt/mud/gravel or whatever it is has more give and lets the wheel turn more freely without necessarily moving forward?

 

[IZwack]

Yes .. if you've ever driven on dirt, you'll see that during a turn, the tires dont follow the same arc -- which means they must be rotating at different speeds. This isnt a problem when the vehicle is not in 4wd because the differential allows the inside wheel to turn slower and the outside wheel to turn faster. In 4wd however, binding occurs because the two driveshafts are now physically connected to each other and now the inside front tire must try to place nicely with not only the outside front tire, but also the inside rear tire and outside rear tire -- none of which is following the same arc (as stated earlier) -- which causes the bind on pavement and pretty much bogs the engine down. But on dirt, the binding doesnt occur because the tires are allowed to slip relative to each other which relieves the bind.

 

[steventadams]

and now the whole dont 4x4 on dry pavement thing makes sense... thanks

 

[MountaineerGreen]

Those Senators are so smart.

 

[IZwack]

But they're always saying one thing, turning around and saying the opposite. Not to mention stealing from your grandkid's college funds

 

[manaen]

You know you should never use 4wd when stealing from your grandkids
Of course having grandkids means you have other issues with binding, that we just won't go into here!!

 

[gijoecam]

You know you should never use 4wd when stealing from your grandkids
Of course having grandkids means you have other issues with binding, that we just won't go into here!!

I almost had milk come out my nose LOL!!!

Not to beat a dead horse, but it's called 'Driveline Bind-up' and as the old foagies around here can attest, any kind of bind-up is a bad thing.

-Joe

 

[manaen]

I almost had milk come out my nose LOL!!!

-Joe

Milk? Shouldn't you be drinking prune juice

 

[gijoecam]

Milk? Shouldn't you be drinking prune juice

Prune juice?? I'm only 31.... I thought prune juice was for OLD people... like in their 40s...

 

[manaen]

Geesh, I'm 35 that means I am almost into prune juice, maybe I can substitute with bad beer, like old mildew or maybe Iron City