Drive Train Vibration.

[samwise68]

Hey all,

Over last weekend we replaced the clutch in my GMC. well, the new clutch is great.

however, there is some vibration coming from the drive train. driveshaft, carrier bearing, u-joint, maybe even loose bellhousing or tranny bolts, idk.

of course we had to take the driveshaft out, and i lost one of the needle bearings in the bearing cap for the rear u-joint that bolts to the rearend. could this cause some fairly mild vibes?

or does the carrier bearing have to be lined up or adjusted in a certain way, to have good harmonics?

anyone willing to chime in, i would appreciate it greatly, just to have some ideas before i go back under it this weekend in attempt to smooth 'er out on the road.

thanks in advance all!

-Sam.

[chevydog66]

The missing needle is probably the culprit. I would have new u-joints and carrier bearing installed and see what happens. Then maybe get the tires balanced.

[Longhorn Man]

a missing needle bearing won't do it.
Do you know about 'phasing' the driveshaft? If it isn't phased properly, you will almost always get a vibration that increases with speed, but seems to go away when you lift off the throttle at speed.

[chevydog66]

Yep, you could pull the driveshaft out rotate it 180* and reinsert.

[samwise68]

well, we didn't pull the driveshaft apart, so i shouldn't have to do the whole "4 splines to the left" thing...i think.

and i attempted to mark the driveshaft to rear end, to get it aligned, but i'll check to see if the u-joints are vertical, and lined up, and if not, i think that'll be the culprit.

would spinning the driveshaft 180, be sort of an instant fix, as far as phasing? just curious, it's all pretty new to me; the only bit on phasing i got out of a Chiltons Chevy - GMC truck book.

thanks again guys!

-Sam.

[Longhorn Man]

I've heard of the remove and turn 180 degrees thing... but since the shaft(s) get ballanced off of the vehicle, and are supposed to be at a perfect ballance.... then this should do nothing.
if you never seperated the two shafts, then ignore my comment on phasing it.

[DavesRide]

You said that you lost a needle bearing. I would re-reinstall drive shaft checking all of the u-joints. I might recommend checking for binding u-joints. I have lost needle bearings only to find one had fallen over and is in the end of the cap. My favorite moment is when I drop on from eye level on a semi dirty floor. Did you put the carrier bearing back from where you removed it in the same exact spot? Here is another description of phazing with visuals I found so I could remember too. The first and last illustrations helped me remember even if just for future projects.

http://www.clubfte.com/users/jniolon...nephasing.html

[crazy longhorn]

Remove the u bolts on the rear yolk, turn it 180 & bolt it back up.....some times this helps with a shaft vibe that is not found in balancing. As Andy stated, the shaft is balanced OFF the vehicle.....so consquently the yolk on the rear diff is not factored in. This may or may not help.....but its cheap to try(I have seen it work in some cases). best of luck,crazyL

[elf w/capital T]

you get it fixed? what did you do? i have the same problem. and going to try what longhorn was saying

[leddzepp]

It has been 3 years....I hope he got it fixed!

[elf w/capital T]

yeah i know, thats why i wish when people get their problem fixed that they post online, they would tell how they fixed it... ha

[leddzepp]

i would start with the u joints, i have found this to be the problem behind driveline vibrations more than anything else.

you may want to start your own thread asking the question, and giving specifics about your problem.
Posted via Mobile Device

[ItsRandy]

My have the U-bolts too tight, deforming the bearing cups and making them out of round or dropped one of the shafts and put a dent in it. A dented shaft is a bent shaft.

[elf w/capital T]

good looking, thank you guys! i figured it was something with tightening my ubolts too tight, i might just go to the junk yard today