Drivetrain 'Squeak' when backing up

[Coley]

Hi guys.
I'm a fairly new member here but I must say there is a lot of good info and well informed people here so maybe some of you could help me out.
I have a '72 1/2 ton with a 350, 2 piece driveshaft and a stock 12 bolt (open) rear end.
I've been picking up on a couple of things lately. First is a cyclic or rotational 'squeaking' in the drivetrain when I'm backing up in reverse....this condition is about 2 months old. Second, "ve been starting to notice a little drivetrain vibration at/above 40mph.
So,....do you think this is U-joints, the hanger bearing....or something else?
Any experience with something similar to this?
Many thanks in advance guys, I appreciate the feedback.
Coley

[blackedoutharley]

Dry u-joints or bad u-joints (or both).

[68gmsee]

As mentioned, u joints or could be carrier bearing.

[Coley]

I was hoping to limit the repair to just U-joints but I wasn't sure of the source of the problem.
The U-joints feel pretty good when I've tried to move them whereas the hanger bearing seems a little 'loose' vertically with about 1/16" to 1/8" worth of play.
Are there any tricks to doing the hanger bearing? Has anyone ever done one? Pressing out the centre part or?
Many Thanks guys
Coley

[cdowns]

for a squeak i'd check the brakes as well as trailing arm bushings and trackbar bushings

[fleetsidelarry]

Originally Posted by Coley

Are there any tricks to doing the hanger bearing? Has anyone ever done one? Pressing out the centre part or?
Many Thanks guys
Coley

the u-joint yoke is splined and bolts to the front drive shaft, it (the yoke) has to be removed before the bearing can slide off. see post #13 in this thread:

http://67-72chevytrucks.com/vboard/s...d.php?t=407861

the play you see is probably in the support rubber, not the bearing itself.

[68gmsee]

Probably need to go through a process of elimination. Squeeks can come from just about anywhere under these old trucks. Try to see if it coincides with the rotation of the tire or drive shaft if possible. Causes can range from the above mentioned areas to loose tire/rim lugs, axle bearings and even a cracked drum.

Here's some previous posts on the driveshaft u-joints, hanger/carrier bearing.

http://67-72chevytrucks.com/vboard/s...d.php?t=416247

http://67-72chevytrucks.com/vboard/s...d.php?t=294596

[Wrenchbender Ret]

That generally is from a bad U-joint. If they have fittings on them you could grease them & it might help for awhile, but it will need to be replaced. If you see rust oozing out aroumd the cups it is a sure sign. It you remove the drive shaft you will find it binding when you turn it.

[Coley]

Great info guys!! Sorry I've been slow on the response but I've been out of town on business stuff and I'm trying to get caught up on a bunch of stuff.
I'll check these recommendations more thoroughly.
Many Thanks!!
Coley