Alright, I posted somthing similar to this a while back and have yet to find the problem. I have a fine vibration that I believe is coming from the rear end of the truck. It's a speed related vibration and is only noticeable when I'm slowing down. When I'm accelerating or maintaining speed it is not noticeable at all, only when you coast or brake. I have ruled out the brakes since it'll do it regaurdless if I brake or if I coast. I have also ruled out the trans since it continues to have the vibration with it shifted into nutral. I'm now at a loss; the only things I can think of are a U-joint, the rearend, or possibly the driveshaft. although the driveshaft I would think if it was out of balance would do it all of the time?? so that leaves me with the other two.

I also have a squeak coming from the front end that is also speed related, does it in both 2wd and 4wd?? front hubs maybe?? a pinion seal?? I have no leaks so I wouldn't think it would be a pinion seal.

Alright guys, lets see what ya got!

 

Rear could be pinion angle or pinion bearing is wearing funny. Front sounds like hubs, mine does it too, only when locked in 4x4 though. They must be dry.

 

Check the ujoints and driveshaft anyway. While accelerating, you are putting pressure on them and may not vibrate. While braking or coasting, the pressure is relieved, and if there is any slop in them it will show up then.

 

Billy bob's right also do you have carrier bearing if so check it to

 

How would I go about checking some of these things? I've crawled under and grabbed the driveshaft and tried to find movement but it certainly isn't sloppy enough that to be moved it by hand.

I'm thinking since good U-joints can be had for $40/peice or so it may be worth replacing them.

There isn't any chance that it could be in my transfer case is there?? Also to make sure my front hubs are unlocking, should I be able to turn the half shafts (or whatever they are called) by hand??

 

Hey jwhitetail here block the wheel's so she don't roll put it in netural yank and twist the drive shaft look for play if you have a carrier the drive shaft run's through it push up and down on it. Yes if the hub's are unlocked you can turn the front axle's by hand and the drive shaft coming out of the transfer case if you can't your still locked in somewhere

 

Steve - First of all, have you eliminated the tires?

U-Joints can "feel" good when just giving them a shake. Sometimes you have to remove them to make sure.

The carrier bearing (swing bearing) might need a shim or two.

As far as the front hubs - if you have ESOF - they can stick in the LOCKED position and cause a "rubbing" sound. Just chock the wheels, make sure the switch on the dash is turned to 2WD, and then crawl or reach under the truck and see if you can spin the axles. The easiest place to spin them will be at the knuckle - just grab the U-Joint and give it a whirl.

 

Alright, I did some checking and drove it a little bit last night. First off my front hubs are unlocking as is the trasfer case. I could rotate both 4wd half shafts at the ujoints and also the front drive shaft out of the transfer case. I also didn't hear the squeak when I was drivng it that I had heard last weekend, as someone else said, maybe the hub seals are a little dry. Is there an easy way to lube them with a little wd40 or pb blaster or a silcone spray??? The hubs were replaced under warranty 2 years ago.

Second line of business, I pushed, pulled, shoved and twisted on my rear drive shaft at each u-joint and at the carrier (mid drivesahft support). The only thing I could get any movement out of was at the carrier. After further examination it looks like the carrier is clipped in place and rests inside a rubber bushing/housing. Once I noticed that I realized that it was not loose at the carrier but instead just moving with the strech/compression of the rubber bushing/housing which seamed perfecty normal. While I was under the truck I checked for an signs of a leak out of the front & rear differential, and at the outer ends of the axle where an axle seal could develope a leak and run the axle/differential out of fluid, to no avalability I was unable to located a single sign of oil or grease any where other then my sloppy grease jobs at the grease zerks, lol. I guess this is maybe a good thing!

Any other idea's guys?? It's not terribly noticeable anymore, but since the first day I notice it, it bugs the crap outa me just because I know it's still there! If this ends up being something expensive I hope its the front or rear diff gears, I know it's a strange thing to wish for but atleast I would have a good reason to swap in a set of 4.30s, lol!

I think my next check will be to check both diffs for fluid level. I would like to check for metal shavings but without pulling the drain plug it would be pretty tough and I'd hate to have to refill and get the right amount of friction modifier in it since I seems to have one of the few LS units that seems to work as it should! Heck the whole truck only has 38k miles on it.

 

Have you tried rotating the tires? If it is a rear tire the vibration will follow to the front tire.

 

I have an appointment for friday for a rotate and balance, comes free for the life of the tires. We'll see what happens then.

 

Get your hands on an angle compass. Check the angle at both ends of the shafts. They should be almost if not exactly the same. Also look for any sign of your shaft factory balance weight falling off. (spot weld with nothing attached) Next through trial and error, get a large hose clamp that will fit the driveshaft and tighten down. Mark the location of the adjustment screw which will act as your temporary weight. Then test drive. If worse or no change, relocate the clamp around the shaft and repeat above until you notice no vibration. I have use this method before when I noticed a weight missing on an old truck I used to own.