Grinding, I think from the t-case

[robwide]

When 4wd is on I've been able to spin the rear wheels on ice or packed snow w/o spinning the fronts. When that happens I hear a grinding noise from under the vehicle. I have a few questions. 1. should I even be able to spin the back wheels when 4wd is engaged? 2. Shouldn't front and rears spin if 4wd is working properly? 3. Is the grinding noise the chain is the t-case? 4. Do I need to start thinking about having the t-case rebuilt or replaced?
Thanks
Robert

This is a 1996 Explorer Sport with Control Trac 4wd and electric shift.
btw- my switch is 2wd, 4wd and 4low... according to the post below it's supposed to be 4auto, 4wd and 4low.
http://www.explorerforum.com/forums/showthread.php?t=203441

 

[robwide]

bump.
really could use some help.
i've read thru a bunch of posts but don't see anything that might relate to my problems.
thanks robert

 

[IZwack]

The front wheels should definitely rotate along with the rear when 4wd is engaged. However, what most drivers dont see is that the passenger's side front wheel is actually spinning while the driver's side is not - which is totally normal since the front axle has an "open" differential. As for the grinding noise, it could be anything but is probably t-case related. Either way, if you are going to do the work yourself, you will need to do more diagnosis because its hard to pinpoint the issue with only this info.

 

[redneck 123]

when i get up to 25 mph i hear a thumpimg noise from the center of the truck it a 2 piece drive shaft thats where it sounds like it is comin from

 

[robwide]

more info... i was wrong about my switch. i assumed it said the same as my light. i guess i'm going blind! anyway my switch does say 2wd, 4wd auto and 4low. my VSS is not working so the ABS, speedo, odo and cruise aren't working right now. don't know if that has anything to do with it or not. i took it for about a 100 mile drive today on icy/snow packed road with it in 4wd auto all day and never slipped on the road once. the 4wd must be working. i'm just still concerned about the grinding sound upon take off sometimes.
Thanks!