Popping noise when suspension articulates

[ugly99]

I've got a noise on a 98 k2500 that I can't find for the life of me. I've read about the slip yoke and some other ideas but I don't think that's what this is.

The noise sounds like it's in the rear center or driver's side. It's a big clunk/pop that happens once when you drive over uneven ground like if you went over rolling hump at a 45 degree angle or when you drive out of a parking lot onto a highway where the ramp onto the highway is sloped. Occasionally it will do it driving over potholes but it usually takes more of a big rolling terrain change, kind of hard to describe, but basically seems like it happens when there's some body rolling involved.

Ive looked at the shocks, leaf springs, drive shaft, body mounts, and such and can't see anything visually. I think my first step is going to be replacing the shocks if nobody else has any ideas that make sense but figured I'd check here for ideas before I start throwing money at it.


Any help much appreciated

 

[Das Hatt]

Try slowly jacking the rear axle up and see if you can re-create what's making the noise.

 

[RichLo]

This may sound odd, but how do your body mounts look? I had a similar situation once and found that one of the cab mounts was barley holding on and it moved in situations like your describing.

 

[Keeper]

Any heavy unsecured objects under or behind the rear seat?

 

[Poutine]

same problem on mine was the front fender liner (metal part) hitting on the frame near the front cab mount. i just bent it a little towards the front

 

[Hipster]

Several things to look at, broken/rusted u-bolt, broken/rusted center pin for the leaf pack, transfer case seal/sleeve can make noise, or could be internal diff noise. All plays into how much digging and reporting back here you want to do along with any other input that might become available.

 

[GrimsterGMC]

Get someone to stand on the tailgate and bounce the suspension to recreate the sound while you lay underneath to trace it.

 

[Schurkey]

On MY '97 K2500, there's a popping noise over bumps with just me driving. If I have a passenger, the popping is practically constant.

There's a failed right-rear cab mount. The cab is rusted away so there's no structure for the mount to support. The cab has sagged on that corner, more with a passenger. There's a reinforcement welded to the underside of the cab that rubs on the driveshaft where the balance weight is welded on. Every time the driveshaft goes around, the weight knocks on the reinforcement.

 

[ugly99]

Try slowly jacking the rear axle up and see if you can re-create what's making the noise.

Tried this. Jacked up by the axle on each side, dropped it slowly, then did it again dropping faster, then did the same thing jacking it by the frame on each side and couldn't get it to make the noise.

 

[ugly99]

Any heavy unsecured objects under or behind the rear seat?

Nope, single cab, nothing in back.