Front diff whine under cruise and decel, not on accel
12-01-2008, 10:20 PM
#21
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Check you're tires diameter. A slight difference between the front and rear tires will load the front diff and make it wine. If the tires arn't identical as far as brand,wear, or size the front diff will make noise. Gm has a procedure to check this you mark all four tires then drive forward 6 or more rotations. If the marks don't line up it can cause you're problem.
12-01-2008, 10:24 PM
#22
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Sorry to hear your problem but it's very common. I just had my front end rebuilt for $1100. I had the same symptoms as your describing and it just got louder and louder. The carrier bearing adjustment nut lock broke and the nut backed off and took everything out. The case was salvageable, barely. Mine isn't the first one this has happened to, mostly on the drivers side bearing. I don't think this is your problem but you will most likely need a rebuild and your gears are almost definitely toast. I suggest changing your fluid. That will tell you quickly the condition your front end is in. Good luck.
12-01-2008, 11:33 PM
#23
If you obtain a front diff. with the same gear ratio, you could use one from a 4x4 by simply pulling off and swaping the passenger side axle tube and one piece axle from your existing unit. Remove the clutch fork assembly from the new 4x4 diff. Once you have them laid out in front of you, you will realize they are really the same except for a few parts. The center housing in our diff's even have the spot for the 4WD actuator. Selectable 4WD (S4WD) have the actuator, while non-selectable 4WD/AWD (F4WD) units do not have the actuator. Also the passenger side axle tube on S4WD units are steel, while the S4WD passenger side tube is magnesium.
12-02-2008, 07:29 AM
#24
If you obtain a front diff. with the same gear ratio, you could use one from a 4x4 by simply pulling off and swaping the passenger side axle tube and one piece axle from your existing unit. Remove the clutch fork assembly from the new 4x4 diff. Once you have them laid out in front of you, you will realize they are really the same except for a few parts. The center housing in our diff's even have the spot for the 4WD actuator. Selectable 4WD (S4WD) have the actuator, while non-selectable 4WD/AWD (F4WD) units do not have the actuator. Also the passenger side axle tube on S4WD units are steel, while the S4WD passenger side tube is magnesium.
12-02-2008, 11:24 AM
#27
Sorry to hear your problem but it's very common. I just had my front end rebuilt for $1100. I had the same symptoms as your describing and it just got louder and louder. The carrier bearing adjustment nut lock broke and the nut backed off and took everything out. The case was salvageable, barely. Mine isn't the first one this has happened to, mostly on the drivers side bearing. I don't think this is your problem but you will most likely need a rebuild and your gears are almost definitely toast. I suggest changing your fluid. That will tell you quickly the condition your front end is in. Good luck.
Looks like my truck's going to be sitting for a long time 
Hope you get yours fixed quickly and easily lafnlt1, If you just swap the whole unit, you should tear the old one apart and take some pics...I'm curious to see what't torn up in there.
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