does the front driveshaft spin even when not in 4 wheel?

Mudman88 · 08-29-2009, 07:47 AM

Subject asks the question. Im thinking possibly my front ujoints are bad, but I didnt think that the front driveshaft moved when it wasnt in 4 wheel.Does it?

leolkfrm · 08-29-2009, 08:27 AM

do you have wheel lockouts? if so no otherwise yes

Mudman88 · 08-29-2009, 08:46 AM

No i dont. Just wondering because when im driving and barely touching the gas I hear something rattling or something...Then if I nail the gas pedal to the floor it goes away until it shifts again, then its back when the RPM goes down..Its wierd..I think its the front UJoints but I dont know.

bubbatrucklover · 08-29-2009, 09:51 AM

Could it be the front u-joint of the rear driveshaft going in to the back of the transfer case?

Mudman88 · 08-29-2009, 12:43 PM

better not be, those were relpaced two weeks ago!I put in both the new front u joints, seems to have helped a little.. That driveshaft seems sloppy to me though

Mudman88 · 08-30-2009, 01:34 PM

The new U joints didnt help

chengny · 08-30-2009, 08:50 PM

Even if equipped with manual hubs (in the disengaged position) it is not unusual to see the front axles and forward drive shaft rotating while the truck is in motion. This "back feed" towards the transfer case is normal and is due to the viscosity of the grease in the hubs. Even though the splines are not physically engaged, the grease provides a sort of "fluid coupling" that will drive the axle/shaft and make it appear that the truck is in 4WD.

But, your hubs are full time - correct? In that case they (the axles and forward D/S) will always be in motion. If the T/C is in 4W they will be locked into the drive train, if in 2WD or neutral the will just be along for the ride. Either way, they will be spinning.

Are you familiar with indexing and phasing of drive shafts? Phase is (see attachments) commonly mixed up and will cause heavy vibration - but is easily remedied.

Indexing is another story. A drive shaft that was not indexed (this simply means marking the relative position of the components to each other) before disassembly can be re-assembled but it will likely be out of balance. Sometimes there are stamped marks on the driveshaft sections to aid in proper reassembly, but most times not.

I realize its too late now but, before tearing a driveline apart, it is good practice to take a can of spray paint and run a good heavy stripe down the entire length. Then, when it is time to put everything back together, there should be plenty of clues no matter how well you cleaned the parts up.

The truck hasn't been lifted lately has it?

Mudman88 · 08-31-2009, 06:35 AM

I marked off the shaft and everything and put it back exactly how it was supposed to be. It was lifted years back, not recently..My roommated stll thinks it may be bad spark knock.But i just put new plugs in it, wires are about a year and a half old.. It sounds bad...And everytime I get it to REALLY rattle, or ping, whatever, the service light comes on,EGR valve code and code 43, Knock sensor..

Mudman88 · 08-31-2009, 05:12 PM

Ok, new finding today. When the service light comes on, it doesnt do it anymore...

08-29-2009, 07:47 AM	#1
Mudman88 Senior Member Join Date: Jun 2009 Posts: 121	does the front driveshaft spin even when not in 4 wheel? Subject asks the question. Im thinking possibly my front ujoints are bad, but I didnt think that the front driveshaft moved when it wasnt in 4 wheel.Does it?

08-29-2009, 08:27 AM	#2
leolkfrm Senior Member Join Date: Mar 2008 Location: N.Y. Posts: 4,300	do you have wheel lockouts? if so no otherwise yes __________________ 4 wheels move the body 2 wheels move the soul B.W.A.I

08-29-2009, 09:51 AM	#4
bubbatrucklover Senior Member Join Date: Jul 2009 Location: Jacksonville, Florida Posts: 426	Could it be the front u-joint of the rear driveshaft going in to the back of the transfer case? __________________ 6" CAN be A LOT when it comes to a body......lift! You CAN outrun a cop you CAN'T outrun a Motorola!

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08-29-2009, 08:46 AM	#3
Mudman88 Senior Member Join Date: Jun 2009 Posts: 121	No i dont. Just wondering because when im driving and barely touching the gas I hear something rattling or something...Then if I nail the gas pedal to the floor it goes away until it shifts again, then its back when the RPM goes down..Its wierd..I think its the front UJoints but I dont know.

08-29-2009, 12:43 PM	#5
Mudman88 Senior Member Join Date: Jun 2009 Posts: 121	better not be, those were relpaced two weeks ago!I put in both the new front u joints, seems to have helped a little.. That driveshaft seems sloppy to me though

08-30-2009, 01:34 PM	#6
Mudman88 Senior Member Join Date: Jun 2009 Posts: 121	The new U joints didnt help

08-31-2009, 06:35 AM	#8
Mudman88 Senior Member Join Date: Jun 2009 Posts: 121	I marked off the shaft and everything and put it back exactly how it was supposed to be. It was lifted years back, not recently..My roommated stll thinks it may be bad spark knock.But i just put new plugs in it, wires are about a year and a half old.. It sounds bad...And everytime I get it to REALLY rattle, or ping, whatever, the service light comes on,EGR valve code and code 43, Knock sensor..

08-31-2009, 05:12 PM	#9
Mudman88 Senior Member Join Date: Jun 2009 Posts: 121	Ok, new finding today. When the service light comes on, it doesnt do it anymore...