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any one know why


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maine
Novice

Sep 26, 2011, 7:40 PM

Post #1 of 3 (1565 views)
any one know why Sign In

got a 2000 gmc sierra 4.3 wd drive and like too know why in front drive shaft turns with rear when in two wheel drive transcaes works in and out of four wheel drive hi and low work but when in two wheel drive both shafts turn i thought front shart on transfercase wounld free wheel


Discretesignals
Ultimate Carjunky / Moderator
Discretesignals profile image

Sep 26, 2011, 8:43 PM

Post #2 of 3 (1532 views)
Re: any one know why Sign In

There is a clutch pack in the transfer case that is applied to lock the front drive shaft to the transfer case gears. When the four wheel drive is selected the transfer case control module locks the front end central disconnect at the same time locking the clutch pack in 4 HI, 4 LOW, and AUTO (when slip is detected).

If you have AUTO, it will lock the front end and will only apply the clutches in the transfer case when it detects a difference in speed between the front and rear prop shafts.

When in 2WD the front end is unlocked and the clutch pack is not applied but still will spin the front prop shaft because there is still some friction in the clutch pack. If the vehicle is in the air you could probably grab the front shaft and stop it, but that isn't a good idea. If the front drive shaft doesn't spin at the same speed the rear shaft is spinning, it will burn up the clutches. Also extremely important to have the same diameter wheels in the front and back.





Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.

(This post was edited by Discretesignals on Sep 26, 2011, 8:45 PM)


maine
Novice

Sep 26, 2011, 9:10 PM

Post #3 of 3 (1526 views)
Re: any one know why Sign In

thank you very much your very smart so its fine that that that front drive sharft turns all the time nothing will happen to front end i know like on the 06 model you can turn front drive shaft in park my 2000 you cant turn it in park i al so have one more thing you might know when idle i feel a vibration when i put it in gear i feel it worse only when idle hope you can help me with that one too






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