Thumping Noise while in 4x4

[fishnmaine]

Ive been having this noise for the last 2 years. While driving in 4 wheel every 20 seconds or so I have this thump noise.( this does not happen in 2 wheel drive) This is while driving in packed snow or ice with some tar showing on the road. When I'm driving in snow I don't hear it. I know I need to change my transfer case shifting motor. Because I've had some issues coming out of 4 wheel drive. sometime i have to drive backwards to release. it will release fine in snow going forward. but on tar and ice I usually hear a good thump noise. Now i don't use 4 wheel much maybe half a dozed times in a course of a winter. Now I know all tires should be at even wear on all fours but i will have to say my back tires are new and my fronts are 75% worn..Hope to hear some input



Thanks

 

[Todd Z]

If the shift motor is bad then its NOT holding the sprag in to 4wd properly. There was also an issue internally that needs replacement if this happens.



Todd Z

 

[Yardsale]

fftopic:

Not a solution regarding the thump, but the tires being (about) the same wear (diameter) is only a concern with limited slip differentials and when using a locked type transfer case 4WD on a surface where the tires cannot slip, which should not be done with this type (locked) transfer case. If using the 4WD as designed, this should not be an issue. Mixed terrain (like the snow with intermittent street, that you note) can cause problems, though.



In the case of limited slip, there are clutch plates that wear when the two half axles turn a different rates. This is not the case with an open differential, as with the front. Also not a problem front to rear with the 4WD not engaged because the front drive is not powered.

:back2topic:

 

[fishnmaine]

Todd Z

I'm looking at the disassembled view of the transfer case, I don't see the sprag listed. Or is this a part in the shift motor.



Thanks