Stupid Question

zachary00 · May 11, 2011

I have a squeak from under my pickup. I assume it is in the drive line because it gets faster as I move faster and become high pitch sound. I can't hear it at +20mph. I think it is a u joint but have replaced both on the back driveshaft. They were definatly bad. Here's the stupid question. Does the front drive shaft turn when moving? Does this sound like a u joint or am I looking in the wrong place?

[email protected] · May 11, 2011

No the front shaft does not turn, however, the front cv's do.

zachary00 · May 11, 2011

No the front shaft does not turn, however, the front cv's do.

so I Guess I need to look at the cv's

kdixer · May 11, 2011

The front drive shaft can turn in 2wd it is just not forced to. The drivers side cv joint is always turning the diff output shaft on the driver side any time the wheel is turning. The drivers side output shaft is permanently linked the the spider gear opposite of the ring gear. The friction or resistance in the carrier determines wether the spider gears allow the differential to either differentiate or turn the carrier which results in the front drive shaft turning. The only thing that disengages in the front end is the passenger side output shaft. That way the left and right side front tires can spin independantly from one another without the spider gears coming into play.

It always cracks me up when people say the front diff is not turning unless it is in 4wd. Oil is always being churned in the front diff anytime the vehicle is being driven no matter what mode you are in.

8.1HD/ALLISON · May 12, 2011

The front drive shaft can turn in 2wd it is just not forced to. The drivers side cv joint is always turning the diff output shaft on the driver side any time the wheel is turning. The drivers side output shaft is permanently linked the the spider gear opposite of the ring gear. The friction or resistance in the carrier determines wether the spider gears allow the differential to either differentiate or turn the carrier which results in the front drive shaft turning. The only thing that disengages in the front end is the passenger side output shaft. That way the left and right side front tires can spin independantly from one another without the spider gears coming into play.

It always cracks me up when people say the front diff is not turning unless it is in 4wd. Oil is always being churned in the front diff anytime the vehicle is being driven no matter what mode you are in.

+1 The front driveshaft is turning anytime vehicle is in motion, its just not locked in the transfer case.

desrtrat · May 12, 2011

bad brake pads have been known to squeak also..just something to conceder also..

good luck

zachary00 · May 13, 2011

what is the best way to diagnose cv joints to isolate which one is squeeking? assuming that is it. I haven't gotten it to do it off the ground yet.

kdixer · May 13, 2011

what is the best way to diagnose cv joints to isolate which one is squeeking? assuming that is it. I haven't gotten it to do it off the ground yet.

Usually cv joints pop and make noise while under load. If a cv joint is dry enough to cause a squeak, you should be able to spot a torn boot or grease flung everywhere around it.

[email protected] · May 13, 2011

The front drive shaft can turn in 2wd it is just not forced to. The drivers side cv joint is always turning the diff output shaft on the driver side any time the wheel is turning. The drivers side output shaft is permanently linked the the spider gear opposite of the ring gear. The friction or resistance in the carrier determines wether the spider gears allow the differential to either differentiate or turn the carrier which results in the front drive shaft turning. The only thing that disengages in the front end is the passenger side output shaft. That way the left and right side front tires can spin independantly from one another without the spider gears coming into play.

It always cracks me up when people say the front diff is not turning unless it is in 4wd. Oil is always being churned in the front diff anytime the vehicle is being driven no matter what mode you are in.

+1 The front driveshaft is turning anytime vehicle is in motion, its just not locked in the transfer case.

um, no. It can turn with enough friction and speed like he said but it does not turn any time the vehicle is in motion. Mine generally doesn't turn at all. If our front diffs were lockers then the shaft would be forced to turn by the diff whether the right output shaft was engaged or not.

hardcore2001 · May 13, 2011

The front drive shaft can turn in 2wd it is just not forced to. The drivers side cv joint is always turning the diff output shaft on the driver side any time the wheel is turning. The drivers side output shaft is permanently linked the the spider gear opposite of the ring gear. The friction or resistance in the carrier determines wether the spider gears allow the differential to either differentiate or turn the carrier which results in the front drive shaft turning. The only thing that disengages in the front end is the passenger side output shaft. That way the left and right side front tires can spin independantly from one another without the spider gears coming into play.

It always cracks me up when people say the front diff is not turning unless it is in 4wd. Oil is always being churned in the front diff anytime the vehicle is being driven no matter what mode you are in.

+1 The front driveshaft is turning anytime vehicle is in motion, its just not locked in the transfer case.

um, no. It can turn with enough friction and speed like he said but it does not turn any time the vehicle is in motion. Mine generally doesn't turn at all. If our front diffs were lockers then the shaft would be forced to turn by the diff whether the right output shaft was engaged or not.

It sounds like a u joint problem for the time it takes to pull the front drive shaft off DO IT this is good PM for your truck and for the cost you may want to change them anyways hope this helps