2nd Bad U-joint... I think.

[03envoy]

Hey Guys,
I'm getting what I would call "slop" in my drivetrain, I would describe it as when my trans is shifting Usually after a downshift and then a quick acceleration I get a little "clunk" and It feels like a bad U-Joint but I'm not certain. Maybe you guys can help. Here is a video:
Thanks,
Trent

http://www.youtube.com/watch?v=GGSsAwI8TQU

[navigator]

on this computer I have a crappy CRT monitor (my LCD died) so I don't get a clear picture on the video. I can't tell from the video how bad the UJoint might be. I haven't had to change a UJoint on a vehicle in many years but it best I recall, my last one I had go out, it started with a little whine and eventually grew to a louder "clank" with a more rotational related sound. What I understand you saying sounds like kind of a one time sound when you have a decent change in acceleration.

I saw a thread either here or on GMTN that said they had some of their torque converter bolts come out. Unless you see some major slop in your Ujoint that I can't see on my crappy monitor, your description would lead me more in that direction.

[Trail X]

There's one portion of your video, at around 30 sec that makes it look loose.

I'm guessing you have your rear axle off the ground and your transfer case in neutral?

I think we'd get much more from a video if you had the transfer case engaged and rotated the drive shaft against the resistance of the engine. See if you can measure a difference in the gap between the two opposing sides of the U joint between torquing the drive shaft in the different directions.

Does the clunk also occur when you shift into drive from reverse?

You say this is the second bad U joint, when you replaced it the first time, did you have the same symptom? Did the clunk go away after you replaced it the first time?

[bgwolfpack]

To check a u-joint…large screwdriver or 3/8 extension between the two halves of the joint. Put pressure in each direction to test for slop in the needle bearings. If there is slop, replace. If no slop it's good.

[03envoy]

There's one portion of your video, at around 30 sec that makes it look loose.

I'm guessing you have your rear axle off the ground and your transfer case in neutral?

I think we'd get much more from a video if you had the transfer case engaged and rotated the drive shaft against the resistance of the engine. See if you can measure a difference in the gap between the two opposing sides of the U joint between torquing the drive shaft in the different directions.

Does the clunk also occur when you shift into drive from reverse?

You say this is the second bad U joint, when you replaced it the first time, did you have the same symptom? Did the clunk go away after you replaced it the first time?

Yes, same symptoms. But this one I think is just starting to go bad. I couldn't replicate the sound this morning. That was with the transfer case in neutral. I didn't have anyone with me to assist in putting it on drive and reverse etc... For future reference I have a video of my first bad U-Joint I will share the link too.

[03envoy]

To check a u-joint…large screwdriver or 3/8 extension between the two halves of the joint. Put pressure in each direction to test for slop in the needle bearings. If there is slop, replace. If no slop it's good.

Going to try this when the rain subsides.

[fishsticks]

I'm pretty sure I saw some slop in that U joint.

[dirty anton]

It Seems A Little Sloppy. I Would Replace It (Relatively Cheep/Easy) And Trouble Shoot From There. Shoot Another Clip If You Can. Curious To See The After Video. Now Why Is My Phone Capitalizing The First Letter Of Every Word IM Writing!

[DirtyBacon04]

There seems to be some good info in this video, not 100% applicable to our platform, but the concept is the same. I wouldn't pay much attention to when he's testing the front wheel u-joints, as we have the CV shafts with a tripot.

Yes... his voice is kinda creepy, serial killer-ish.

[03envoy]

Here is a video I took really quick. The u joint at the transmission feels tight, but if you notice the "slack" in the video, is that normal?

http://youtu.be/W_RdIK-ZjVM

[HARDTRAILZ]

I have similar noises and checked my u-joints...Good.

I have an inkling it is a motor mount going bad as when stopped the whole truck will shift on the supension when you go from drive to reverse or reverse to drive while holding the brakes. But the motor does not seem to shift too much, but never paid attention before the noise, so it may be same or increased of time.

Barton told me, sight unseen, just from my phone call/emails, that he thinks it is play in the Transfer Case gears. Said his truck does it and it is fairly common. That as things wear, there gets to be a bit of slop in the teeth and you start to see/feel it.

I like his idea because it is more of a non-issue, but hopefully when I see him and some other members Sunday at Badlands, we can get a better diagnosis of the noise cause.

[03envoy]

I have similar noises and checked my u-joints...Good.

I have an inkling it is a motor mount going bad as when stopped the whole truck will shift on the supension when you go from drive to reverse or reverse to drive while holding the brakes. But the motor does not seem to shift too much, but never paid attention before the noise, so it may be same or increased of time.

Barton told me, sight unseen, just from my phone call/emails, that he thinks it is play in the Transfer Case gears. Said his truck does it and it is fairly common. That as things wear, there gets to be a bit of slop in the teeth and you start to see/feel it.

I like his idea because it is more of a non-issue, but hopefully when I see him and some other members Sunday at Badlands, we can get a better diagnosis of the noise cause.

The transfer case is exactly where most of my play is coming out of. It seems the only solution would be to replace the transfer case? One thing that bothers me, is that when I Replaced the one u joint it seems to temporarily fix the issue. I am at a loss as to what has caused this because the only time I've been using 4wd has been in the winter. The drivability with "Thump" I've been getting sucks. What am I looking at when replacing it? relatively easy? One last question... does an SS transfer case fit id assume?

Trent

[03envoy]

Here's a video at the transfer case:

http://www.youtube.com/watch?v=Yxvkxsx92EA

[v7guy]

It looks like there's some slop in the joint, but it's kinda hard to tell. The ole screwdriver trick didn't work for ya?
SS transfer case? Do you like selectable 4wd?

[03envoy]

Yea. And I didn't even think about them being AWD.

[03envoy]

If anyone has the time, can they get under there truck in neutral and take a video of them similar to mine to compare? Also take a quick video of them spinning the rear wheel and stopping it suddenly by hand? Just so I can compare to what seems normal.

Trent

[03envoy]

Can anybody shed some light on this?

[DirtyBacon04]

I'd say just replace it. Even the ACDelco u-joints on Rockauto are only 12-14 bucks. If it didn't solve the problem, at least you got a spare!
From my understanding, there's always gonna be a lil "slop" in the drivetrain. And the older the vehicle gets, the more slop it'll develop.
The important part in bearing diagnosis is isolation. Isolate your suspect bearing from any other moving part connected to ensure any play you are feeling is from the suspect bearing.

[03envoy]

I'd say just replace it. Even the ACDelco u-joints on Rockauto are only 12-14 bucks. If it didn't solve the problem, at least you got a spare!
From my understanding, there's always gonna be a lil "slop" in the drivetrain. And the older the vehicle gets, the more slop it'll develop.
The important part in bearing diagnosis is isolation. Isolate your suspect bearing from any other moving part connected to ensure any play you are feeling is from the suspect bearing.

Both u joints are fine. That's what I don't understand. It's either linked to rear differential or transfer case, but I have no idea what the standard "slop" is to compare too.

[DirtyBacon04]

Are you feeling any vibrations while driving (other than the "clunk"). if so, are the vibrations consistent with road speed?