Rear-end clunk/thunk on one side when going over bumps

Need help folks...
'98 V6 4WD XTRA cab w/ MT. I pretty much overhauled the entire suspension both front&rear. The rear is giving me issues. I replaced the leaf springs with the Autozone brand 'stock ride' replacements. I also replaced the rear shocks with some bilstein 4600's, which I ordered from 'shock surplus' (they arrived in what seemed to be new condition, in the original bilstein box, no defects, nothing weird, etc.)

This was my 1st time ever doing this type of suspension work, but, as far as I could tell, everything went more/less smoothly. I followed the FSM install instructions to the letter.

Also, fyi, this is for basically a stock truck that's going to be meant as a daily driver, so it doesn't have any lift kits or anything like that.

Anyway, I'm getting a bad 'thunk' / 'clunk' on the rear right side when going over any type of bump / pothole. It's almost as if the suspension is unloading & thrusting/slamming the right rear tire down to the ground as it goes over the bump and the tire 'catches air' for an instant (sorry, not sure how to describe this). The driver side doesn't seem to be doing this.

So, I'm wondering if I got a bad rear shock, bad spring, or if there might be something else that's off??? How can I check these parts & see if they're ok?

I should also mention that the rear end feels super stiff in general, and the ride is very rough & pretty much sucks overall. I'm just assuming it's because everything is brand-new & the bed is unloaded, so it's going to take a while for everything to loosen up. So, I'm just gonna have to suck it up for a while. Am I right or wrong about this?

Anyway, this is what I've checked so far
- made sure everything on the rear suspension is tight & torqued to spec, such as the u-bolts & shock mount bolts, etc.
- tire pressures are good
- spare tire is mounted tight
- body mounts are tight / no play
- rear wheel bearings seem ok, nothing weird going on that I can tell

My next step is to try to mount a gopro under there, but I figured I'd check here first to see if anyone has any ideas...

 

Noises can be so tricky it could be anyplace.

With the rear suspension off the ground supported by stands under the frame and a jack under the differential taking some weight prying on everything with a bar.

Exhaust hitting something?

Transmission or Engine Mounts .

Front end bushings .

Possible drive line issues . Even a CV axle making noise

Good Luck!

 

I had a similar situation with my truck a couple months ago and it did end up being the rear wheel bearings, but I couldn't tell by lifting up the truck and manipulating the wheel in any way.

Just ruled every other possible cause out, then decided to go ahead and replace the rear wheel bearings. Solved my problem and no clunks since.

Might add to advice @Bivouac gave above, that I like removing the rear tires with the rear end of the frame up on Jack stands and letting the rear end fully droop (removing jack from under the rear diff), and then prying on things to see if you can replicate the clunk.

 

thanks for the feedback guys, but it ended up being something really dumb...

When I did the rear suspension, I had a helper handing me tools & parts. This person screwed up when handing me the rear shocks due to the way I had them laid them out for L & R sides. I was in a hurry to get the job done, so I didn't bother to double-check the part numbers for the driver-side & passenger-side Bilstein 4600's, to make sure things were right, since I just assumed I was handed the correct part.

Anyway, turns out I had them on wrong. The driver-side rear shock was on the passenger side, & vice versa. I immediately swapped them, went for a drive, and things seemed more 'normal', but now I'm worried that I might've damaged the shocks by having them swapped.

Since this truck is still in progress, I hardly drove it with the shocks like that. Just a few light test drives on neighborhood streets and some freeway driving before getting it smogged. I haven't driven it hard or gone off-road. What are chances I might've damaged something?

Apparently, the rear-right shock is like 1/2" longer than the rear-left, which doesn't seem like much, but I guess it was enough to cause problems.

Any thoughts on if I should be ok, or if I trashed my new shocks?

 

Shocks should be fine.

And all the torqueing of fixtures with bushing was done in compression (not droop) correct?

 

You should be fine.

 

Do you still have symptoms (clunk/thunk) in the rear? I doubt you damaged anything to be honest.

 

yup, on the ground, with the suspension fully loaded. Same for the leaf spring bolts & shackles.

 

Then you should be good. Only worry if the noise gets louder, or longer.

 

the hard 'clunk' seems to have gone away, but I need to go on a longer drive. I'm pretty sure the shocks were the problem.

 

I am going to say the clunk was axle wrap. Now that they are switched to the appropriate place. You should be good.