Driveshaft bump? Universal joints? slip yoke? (1 Viewer)

[Lancruza]

I have a 1997 80.

I've started getting a bump in the rear of the drive line. Sometimes it does it and and sometimes it's fine. It seems if I turn right it creates the problem and then when I turn back left, it goes away.

It is a repetitive bump. I'm guessing here, but it sounds like the driveshaft is hitting something as it spins. The faster I go, the bump increases in speed.

I've been reading about the rear end clunk in some other posts, but I'm not sure if this is the same problem that they are referring to.

I'm considering removing the rear drive shaft in order to inspect, clean, and grease. Is this where I should start?

 

[jonheld]

Inspect the clearance between the muffler and the universal joint. I've had an issue with this in the past.

 

[nukegoat]

Driveshafts spin faster than people realize. Is this noise high frequency (like engine rpm)?

 

[Lancruza]

Driveshafts spin faster than people realize. Is this noise high frequency (like engine rpm)?

The bump I'm noticing is much more noticeable at low speed, 1-10mph. As speed increases, so does the bump speed. When driving at normal speed, i don't notice it. It has gotten progressively more noticeable over the past few weeks. I put a few squirts of grease in the rear driveshaft u-joints. I did not grease the slip joint yet. I'm not sure when any of the u-joints or slip joints have been serviced.

 

[nukegoat]

The bump I'm noticing is much more noticeable at low speed, 1-10mph. As speed increases, so does the bump speed. When driving at normal speed, i don't notice it. It has gotten progressively more noticeable over the past few weeks. I put a few squirts of grease in the rear driveshaft u-joints. I did not grease the slip joint yet. I'm not sure when any of the u-joints or slip joints have been serviced.

My point is that the rotational frequency of the driveshaft is very different than a tire or wheel.

 

[Lancruza]

My point is that the rotational frequency of the driveshaft is very different than a tire or wheel.

Yep, totally get it. I was just trying to explain the frequency of the bump. Considering the lack of responses, this must be a rare and isolated occurrence.

 

[nukegoat]

Yep, totally get it. I was just trying to explain the frequency of the bump. Considering the lack of responses, this must be a rare and isolated occurrence.

Put a go pro underneath your rig.

 

[BILT4ME]

Which end is the slip yoke on each DS?

 

[Lancruza]

Inspect the clearance between the muffler and the universal joint. I've had an issue with this in the past.

Thanks for the reply. I checked this and there are no clearance issues.

 

[Lancruza]

Which end is the slip yoke on each DS?

My 80 is a 1997 model.

My rear driveshaft has the slip yoke next to the transfer case. My front slip yoke is next to the axle.

 

[BILT4ME]

My 80 is a 1997 model.

My rear driveshaft has the slip yoke next to the transfer case. My front slip yoke is next to the axle.

OK. That part is as it should be.

Any section of exhaust close to touching the DS?
How about sway bar bushings or links that are broken, allowing it to come into contact with a DS?

Otherwise, I would lean toward U-Joints.

Also, engage the CDL and see if the bump goes away. This can help isolate it to something slipping.

I have a "bump" hat my truck makes after it is fully warmed up (drive for an hour), then as I come to a stop sign and pull away, about 5 feet into movement, I feel something shift that make a bump sound (not shift as in shifting gears). My rear pinion seal is leaking and I am leaning towards a loose rear pinion or worn bearings, but I have not had time to fully inspect it. I purchased a new rear DS (not installed yet) because it feels like the splines are worn and it is pushing past a worn section on the splines.
My bump does it once, then it's done for a while.

If yours is constant during movement, then it must be a brake caliper or pad, a U-Joint, a bearing, or an axle shaft.

 

[Lancruza]

OK. That part is as it should be.

Any section of exhaust close to touching the DS?
How about sway bar bushings or links that are broken, allowing it to come into contact with a DS?

Otherwise, I would lean toward U-Joints.

Also, engage the CDL and see if the bump goes away. This can help isolate it to something slipping.

I have a "bump" hat my truck makes after it is fully warmed up (drive for an hour), then as I come to a stop sign and pull away, about 5 feet into movement, I feel something shift that make a bump sound (not shift as in shifting gears). My rear pinion seal is leaking and I am leaning towards a loose rear pinion or worn bearings, but I have not had time to fully inspect it. I purchased a new rear DS (not installed yet) because it feels like the splines are worn and it is pushing past a worn section on the splines.
My bump does it once, then it's done for a while.

If yours is constant during movement, then it must be a brake caliper or pad, a U-Joint, a bearing, or an axle shaft.

It's intermittent. That's why it has me stumped. It doesn't do it all the time. It's coming from the back of the truck. "Nukegoat" has a good idea. I'm going to try and mount a GoPro underneath and see if I can spot anything.

 

[BILT4ME]

It's intermittent. That's why it has me stumped. It doesn't do it all the time. It's coming from the back of the truck. "Nukegoat" has a good idea. I'm going to try and mount a GoPro underneath and see if I can spot anything.

I've though of doing the exact same thing, except I don't own a GoPro.

 

[jonheld]

If something is rubbing on the driveshaft it will show a shiny spot. Pretty easy to see with regular eyeballs.

 

[Lancruza]

If something is rubbing on the driveshaft it will show a shiny spot. Pretty easy to see with regular eyeballs.

Yep, I don't think anything is rubbing. I've looked for marks on the driveshaft and I don't see anything at all. Something is causing the noise though. I'm hoping the camera will show what the driveshaft is doing. Maybe show it being in a bind or whatever is happening.

 

[Broski]

Inspect the clearance between the muffler and the universal joint. I've had an issue with this in the past.

^^^ this

 

[jonheld]

Yep, I don't think anything is rubbing. I've looked for marks on the driveshaft and I don't see anything at all. Something is causing the noise though. I'm hoping the camera will show what the driveshaft is doing. Maybe show it being in a bind or whatever is happening.

Have you checked the simple things first?
Lug nuts
Drive shaft bolts
Suspension bolts