Just changed my Transfer Case.. have to use Reverse to get out of 4x4????

[tpstaples]

Has anyone run into this?

I literally just yesterday finished replacing my transfer case in my 91 explorer 4 door automatic electronic 4x4 shift.

The old one was screeching and howling and clunking when trying to use 4x4.

So.. i replaced it.

Now, 4x4 works fine.. but when I turn it off (while stopped even) and go forward, i hear a sound like..

grind grind grind CLUNK... grind grind grind CLUNK

the only way i can get it to not do that is to put the truck in reverse and go about 20 feet, then when i go forward, there's no issue.

any ideas as to what's going on?

is it spec that these trucks must go in reverse before they really get out of 4x4? This was my mother's truck before mine and I thought i heard her say at one point that she used to have to go in reverse to get out of 4x4.

thanks

 

[dman726749]

yep, reverse unlocks the auto hubs

 

[tpstaples]

really?

so all that grinding and clunking is the way it's supposed to act?

 

[Robb]

so all that grinding and clunking is the way it's supposed to act?

Not really, because you aren't supposed to drive forward without unlocking the auto-hubs. The hubs can only unlock themselves by running backwards.

A simple owner's manual would explain this.

 

[tpstaples]

i would have read it, if i had one.. but i dont.. so i didn't, hence the reason i asked you brilliant wonders

 

[MrShorty]

Not really, because you aren't supposed to drive forward without unlocking the auto-hubs. The hubs can only unlock themselves by running backwards.

A simple owner's manual would explain this.

I beg to differ with you on this. While it's true that you have to back up to unlock the auto hubs, you should be able to drive forward with them locked in in 2H without any uncomfortable bangs, grinds, or moans. When I had auto hubs, I would leave them locked all the time, and now that I have manual hubs I still leave them locked in when I anticipate needing the 4WD.

Can you give a better description of when it bangs? Only when it's in 2H with the hubs locked? If you shift from 4H to 2H while driving, does it do it? Does it ever bang while in 4H?

 

[DeRocha]

I'm with Mr.Shorty on this. You should be able to engage 4x4, shut if off and continue driving normally (without reversing direction). Where exactly are you hearing the noise from (the T-case or wheels). When you engage 4x4 does it work ok without these noises?

 

[Brain]

'91 Owner Guide (page 130):
"Your vehicle's front axle automatic locking hubs will automatically disengage after the transfer case is shifter to 2H and the vehicle is driven in the opposite direction for a minimum of 10 feet (3 meters) in a straight line. This disengagement of the automatic locking hubs, which is not required for two-wheel drive operation, stops all movement of front-wheel drive components while operating in two wheel drive."

That said, when the transfer case disengages the front drive shaft, the tires should be able to move independently because the front differential would allow it to do so. I had something similar (thunking like the wheels were skidding when turned sharply going forward slowly) so I took it into a dealer's shop (when it was still under warranty) and they replaced both front hubs and the issue was solved.

Those hubs are expensive, so I would either rebuild them, swap to manual hubs, or live with reversing to disengage them. You get better gas milage when they are unlocked (either automatically or manually) because there is less drivetrain resistance to overcome with engine power.

 

[Positive Vibes]

Like Brain said.

To disengage the hubs you have to go the "opposite direction" you were driving in in 4x4.

Also sounds like your hubs may be bad or going bad. Manuals are the way to go, 2 manuals cost the price of one auto.

 

[Blee1099]

Not to mention more reliable. Wouldn't you just hate it if you had auto hubs and they failed when you needed them most.

 

[Brock94]

To focus back on the problem though, the truck shouldn't make any excessive noises driving forward in 2H with the hubs locked. When I do this, I can detect a faint whirr from the front drivetrain spinning, but nothing else.

It sounds like there is a problem with your front drivetrain-- maybe a u-joint or something.

 

[Glacier991]

I wouldn't automatically jump to a hub replacement option without exploring the drivetrain to the hubs first.

 

[Brain]

I agree. Check the front driveshaft and alxe u-joints for excessive play/slop.