U-Joint or what? Click noise

[XhaloZ]

Ok guys I have a 96 GMC Sierra. Whenever I floor it or DOWNSHIFT it makes this really FAST but not too loud clicking noise. Now I've heard jeeps with bad U-Joints but they are far more noticeable than my truck. I just wanted to know if you guys know any other possible solutions to my problem. It sounds like it's coming from the rear and not underneath me so I don't think it's the transmission. It almost sounds like when you are pouring rice into a jar haha (closest sound I could get) but it is noticeable. My truck doesn't chug, hesitate or jump when I shift into gears. Any help would be much appreciated.. thanks gang!!

[maxwedge]

Pretty tough to diagnose noises in this environment, pull the shaft and check the joints, have an experienced tech drive with you.

[XhaloZ]

When I check the joints what am I looking for to indicate they are bad?

[gmvortec]

Rotate the joint thru its operating axis,if it's rough,has play or siezing up it needs replacing, if it has a grease nipple on it you could try greasing it before you remove the shaft, but if it is worn it won't be long before you are replacing it anyway. If you do take the shaft off to check it that way, for the few extra minutes and for the in expensive cost i personally would just fit a new joint.

[XhaloZ]

Originally Posted by gmvortec

Rotate the joint thru its operating axis,if it's rough,has play or siezing up it needs replacing, if it has a grease nipple on it you could try greasing it before you remove the shaft, but if it is worn it won't be long before you are replacing it anyway. If you do take the shaft off to check it that way, for the few extra minutes and for the in expensive cost i personally would just fit a new joint.

Ok cool thanks... that sounded like something out of a porn scene but I got it and I will check it this weekend.

[sector95]

Do you have a single or 2-peice drive shaft?

Short bed=1 peice

Long bed/Extnd'd Cab=2 peice

Agree with potential U-joint failures.....Probably have them all replaced and replace them with greaseable joints. The 1 peice drive shaft has only 2 joints; the 2 peice has 3 or 4 plus a center bearing support which can go bad also....

The 1 peice drive shaft also has a requirement to periodically grease the front slip yoke where it engages the tail shaft of the transmission....an often neglected service.

Good luck

Mike
98Sierra

[XhaloZ]

Yeah it's a one piece.... it has 2 u joints. Man I'm thinking it's something else because the drive shaft rotates every so slightly left and right but I get no play between either u-joints (front and back). I thought maybe the squeeky sound was coming from my rear tires but it only happens in gear. When I am in reverse it sounds like a damn rat squeeling and it only happens in gear and when I go into first gear it does the same sound until I get up to speed. You still think it could be the u-joint? I'm going to take a look at it this weekend and replace it and see if it fixes the problem.

[sector95]

U-Joints can fail in many ways....they don't always get loose and sloppy. If these are the original joints then they are probably at the end of their useful service life. Sometimes the joint can be tight....but internally the grease has hardened or the rubber seals on the bearing ends have failed (or both) and allowed water into the joint...the combination creates a messy goop of old grease and rust that will eventually sieze the joint...and when that happens you run the risk of destroying the yoke assembly (where the u-joints press-fit into the driveshaft and transmission slip yoke). The squeaky sound you hear might be the bearings of the joints failing due to lack of lubrication.

If you have the single drive shaft you *must* pull the driveshaft, clean and regrease the slip yoke (the part that slides into the splined tailshaft of the transmission) on a regular basis (maybe twice a year or so). Failure to do this can cause some driveshaft clunks when moving off from a stop. Greasing allows the drive shaft to move in and out of the transmission tailshaft spline freely as the rear suspension moves up and down. Nobody likes to do this because it requires you to remove the driveshaft....and it's kind of a pain to do. After you clean the slip yoke splines, use some good, viscous water proof grease (I use Bel-Ray water proof bearing grease which you can find at most motorcycle shops) ....normal chassis grease tends to thin out too much and you don't want it to mingle too much with the tranny fluid.

Mike
98Sierra

[mad1517]

I have a one piece drive shaft with 2 u joints,speaking of these do you recomend greaseable or non,also how much grease do you put on the slip yoke and what are some other types of grease you can use or you suggest,maybe the green grease that water proof stuff.Thanks for any help

[Z15]

The only indication I had bad u-joints on my 1992 was squeaking. had the dealer check it out and he showed me the rear joints were total rust and worn to nothing. 80,000 miles on the oem joints.

[sector95]

Originally Posted by mad1517

I have a one piece drive shaft with 2 u joints,speaking of these do you recomend greaseable or non,also how much grease do you put on the slip yoke and what are some other types of grease you can use or you suggest,maybe the green grease that water proof stuff.Thanks for any help

Me, myself and I like the greaseable kind of u-joint on my truck....because *I* know when and how often these joints have been serviced.

For the slip yoke.... I first thoroughly clean out as much of the the old grease as possible (carb cleaner and a tooth brush works good for this). BEFORE you pull the shaft, make sure you match-mark the driveshft to the rear axle u-joint saddle ("White-Out" correction fluid works great for this). You really can't do much with the tranny tailshaft itself. I use my finger and a small brush (like a welders flux brush) and slather a good coating of waterproof grease ( I use Bel-Ray grease cause I have a dirt bike....I guess the "green stuff" will be okay but I've not used any other stuff than the Bel-Ray grease) into the splines and interior of the slip joint...make sure you get complete coverage. Then reassemble the driveshaft and you should be good for 6-8 months.

Mike
98Sierra