Clunk Going Into Gear - UJoint?

[JPVortex]

Hey y'all 2002 Suburban 1500 5.3, 4L60e with a 10 bolt rear. Noticed this clunk, particularly when shifting into reverse. Can hear it sometimes in drive as well. Sounds to me like it's coming more from the rear. Hard to pinpoint the source of the sound. Not sure if it's a ujoint that's starting to show its age, the trans mount, the trans itself, or the rear end. Don't notice anything weird when driving.

Sorry for the annoying exhaust sounds and the lifter tick, really noticeable from under here lol.

I have videos here:

Rear end(2 videos):

Front end:

Thanks y'all!

 

[JPVortex]

Honestly to me this sounds like a bad ujoint, and they’re all the original nylon injection ujoints. I think I may just go ahead and order 4, then replace all of them on the truck.

May go with moog, seems like the moog ujoints actually have better reviews than the gm genuine ones.

 

[strutaeng]

Seems kinda normal to me TBH. Unless the video isn't picking up the real sound?

You could simply remove the driveshafts and move the u joints to see if they are still or seized. But replacement is not a bad idea because they do wear out, especially if you live in the rustbelt regions.

 

[JPVortex]

Seems kinda normal to me TBH. Unless the video isn't picking up the real sound?

You could simply remove the driveshafts and move the u joints to see if they are still or seized. But replacement is not a bad idea because they do wear out, especially if you live in the rustbelt regions.

Ok it does? I’ve never heard a vehicle straight up clunk going into gear, sounds like a metal clunk. Might need headphones to hear it. I was on flat ground too not a hill.

 

[rockola1971]

Looking at the video showing the rear ujoint at diff while the video is enlarged I can see the pinion jump during the clunk, not the ujoint end of it either. I suspect your clunk is in your rear diff. Id pull the cover off and have someone move driveshaft back and forth just slightly and see whats going on in that diff. Likely wear and tear on the gears. You should be able to see the wear on the teeth. Dont forget to block the wheel(s). I did not see any play in the ujoint, but it being original it will likely need to be replaced at its age.
You can always just replace the ujoints since they need it anyway and then see if you luck out and thats all it needed BUT I would pray before and if it turns out to be just Ujoints, go buy a lottery ticket.

 

[JPVortex]

Looking at the video showing the rear ujoint at diff while the video is enlarged I can see the pinion jump during the clunk, not the ujoint end of it either. I suspect your clunk is in your rear diff. Id pull the cover off and have someone move driveshaft back and forth just slightly and see whats going on in that diff. Likely wear and tear on the gears. You should be able to see the wear on the teeth. Dont forget to block the wheel(s). I did not see any play in the ujoint, but it being original it will likely need to be replaced at its age.
You can always just replace the ujoints since they need it anyway and then see if you luck out and thats all it needed BUT I would pray before and if it turns out to be just Ujoints, go buy a lottery ticket.

Kind of seems like it right? Seems like the pinion is “jerking” a bit. Should the pinion stay completely still while shifting into gear? I was firmly on the brakes during the video, so I’d think it shouldn’t jerk like that. No weird noises driving or anything, it’s strange, really is.

 

[rockola1971]

Kind of seems like it right? Seems like the pinion is “jerking” a bit. Should the pinion stay completely still while shifting into gear? I was firmly on the brakes during the video, so I’d think it shouldn’t jerk like that. No weird noises driving or anything, it’s strange, really is.

It should not jerk like that. You can see it take up play in the video during the clunk. You wouldnt hear it driving. Only going from a dead stop into gear and maybe when backing off the throttle.

 

[JPVortex]

It should not jerk like that. You can see it take up play in the video during the clunk. You wouldnt hear it driving. Only going from a dead stop into gear and maybe when backing off the throttle.

Yeah, so it's seeming like rear end might be on its way out. The front driveshaft does have a little jerk to it to, less than the rear though. What a pile of junk this truck is turning out to be. Going to need cam/lifters at the minimum(possibly a whole engine dropped in, oil pressure is slightly low too) and now the rear end? I mean give me a break. Things a pile of junk.

 

[JPVortex]

I can see from the video, almost looks like the pinion is very slightly coming in and out? I've got to check it for play in the morning. I think the rear end isn't happy at all.

 

[JPVortex]

This guy seems to have had a similar issue to me, his turned out to be worn out spider gears. Willing to bet I have something similar going on.

Don't know how to work on differentials at all, so I think I'll run it until the differential can't go no more and swap in a used unit.

 

[Joseph Garcia]

Honestly to me this sounds like a bad ujoint, and they’re all the original nylon injection ujoints. I think I may just go ahead and order 4, then replace all of them on the truck.

May go with moog, seems like the moog ujoints actually have better reviews than the gm genuine ones.

There are a number of possibilities regarding the source of your noise. I recommend that you go to a trusted local repair shop and get it up on a lift with someone inside the truck. Then go through the actions that generate the noise, and a mechanic will look around underneath the truck, with a stethoscope if necessary, and identify the source of the noise. Otherwise, you are just firing the parts cannon, hoping for a solution.

In my case, my front differential mounts were worn out, and as soon as they were replaced, the noise was gone.

 

[JPVortex]

There are a number of possibilities regarding the source of your noise. I recommend that you go to a trusted local repair shop and get it up on a lift with someone inside the truck. Then go through the actions that generate the noise, and a mechanic will look around underneath the truck, with a stethoscope if necessary, and identify the source of the noise. Otherwise, you are just firing the parts cannon, hoping for a solution.

In my case, my front differential mounts were worn out, and as soon as they were replaced, the noise was gone.

Yeah not a terrible idea, kind of difficult to do the proper diagnosis on jack stands.

Funny enough, one of the front differential ears that attach to the mount is cracked. Wonder if that has something to do with it. Need to have the front differential welded or replaced.

 

[rockola1971]

Yeah not a terrible idea, kind of difficult to do the proper diagnosis on jack stands.

Funny enough, one of the front differential ears that attach to the mount is cracked. Wonder if that has something to do with it. Need to have the front differential welded or replaced.

I can honestly say Ive never heard of anyone in a truck chassis have their front diff assembly completely separate from the chassis while cruising down the road. Dont be that guy. If you do though, we want video!

That vehicle has been hit hard previously. Diff mounting ears dont crack easily or usually.

 

[JPVortex]

I can honestly say Ive never heard of anyone in a truck chassis have their front diff assembly completely separate from the chassis while cruising down the road. Dont be that guy. If you do though, we want video!

That vehicle has been hit hard previously. Diff mounting ears dont crack easily or usually.

Probably from when the previous owner had a tree fall on it. Theres a small dent in the roof and the hood was replaced because of it.

 

[S33k3r]

One other thing you might consider: Do you have a G80 in this? Regardless, when was the last time you replaced the differential fluid? If you do have a G80, there is a supplement that's supposed to be added every 15k miles, if memory serves...

 

[Fless]

If you do have a G80, there is a supplement that's supposed to be added every 15k miles, if memory serves...

Never heard of anything like that; how about a firm reference to such a recommendation?

I say just use the right fluid and change at proper intervals.

 

[JPVortex]

One other thing you might consider: Do you have a G80 in this? Regardless, when was the last time you replaced the differential fluid? If you do have a G80, there is a supplement that's supposed to be added every 15k miles, if memory serves...

Not a g80, open GT4 3.73 axle. Thanks though.

 

[JPVortex]

Will definitely open the rear up soon and change fluid and inspect though.

 

[S33k3r]

Never heard of anything like that; how about a firm reference to such a recommendation?

I say just use the right fluid and change at proper intervals.

I was wrong:

the G-80 conundrum

 

[JPVortex]

Well folks update, definitely am feeling some sort of drive train vibration coming to a stop and taking off. Not sure if it’s the engine misfiring due to the bad lifter or the drivetrain.