Possible Drivetrain/U-Joint Issue

Within the past few days, I have noticed my truck making a pretty noticeable *clunk* when the truck shifts gears between about 30-40mph. It clunks pretty good, enough so that it almost feels like the whole truck clunks forward and back. This has only clunked this badly a few times, but considering it's been every day I've driven the past 3 days it has me a bit concerned. I have also experienced the more common clunks when shifting from park/reverse to drive or in stop-and-go traffic.

I've been pretty adamant about greasing the zerks under the truck with every oil change(5-7k miles), but have only been doing so for the past 15,000 miles - before that, I'm sure they were never greased. The last time I greased up down there I noticed that after just two pumps with my grease gun, I saw grease pressing out from the joints, almost as if the seal failed sending grease out. With the noticeable clunk driving at higher speeds, along the regular stop and go clunkin I'd like some input on if I need to change my seals, joints, entire driveshaft, etc.??

Thanks in advance

 

If you're just now getting grease coming out of them, there's a good chance they've been dry for a long time. They are designed to expel old grease as new is pumped in. Damage might already be done.

 

I mean, replacing u-joints isn't horrible. You're probably due. Go with Dana/Spicer.

But what's up with that carrier? Is it hanging low and center? or low and to one side? It should have a little play, is everything otherwise OK?

 

U-joints usually fail by either binding up or the needle bearings turn to fairy dust, often accompanied by clicking while underway or a good clunk when reversing the driveline direction. To check for bearing damage, jack all 4 off the ground, put the transfer case in neutral and rotate the joints while pushing every which way. Any movement in the spider vs. the caps means the needles have left the chat. There will usually be a rust stain present. You can sometimes detect binding it by rotating the driveline by hand - or by dropping one end of it and manipulating the joints by hand.

 

Definitely check out u-joints. Honerable mention for the transmission mount sitting on the cross-member. Make sure your bolts are actually there and torqued down.

I just had my carrier bearing and u-joints serviced. Had a clunk and lunge when switch driveline direction and moderate vibration between 40-55 mph. Vibration is gone and so is clunking. Lunge is still there but not as pronounced and is more sporadic; however I don’t know a truck over 175k that doesn’t do that.