Real puzzle, front end mystery noise

Hello. My 96 4.0HO automatic, 8.25rear has a front end noise. It only happens when going over the small washboard type bumps. I mean, really, really small bumps when going straight. Its not a pop or a clunk like a tierod or ball joint popping. Its more of a subtle clunk, like something is loose up front, but after weeks of searching, banging, and cursing at various suspension components, i cant find a damn thing loose.

The skimpy on the beast:
Within the last 2k miles:

Sway bar endlinks
Sway bar frame bushings
Upper and lower IRO adjustable control arms
IRO double shear track bar
ZJ tie rod upgrade, new drag link
Steering box tightened and checked for cracks in frame
New bilstein 5100s
All motor mounts

Pretty much everything aside from ball joints, u joints and hub bearings, which will be done no later than december anyway. The balljoints have super minimal play, nothing that i saw needed to be replaced immediately, and my u-joints are similar, minimal play but quite rusty.

Ive never really had ball joints or a hub bearing make this kind of subtle, hollow knock (really its like a hollow rattle that corresponds to the washboard bumps)over tiny bumps, but then again this is my first XJ. Im used to my Volkswagens just wanting to spit a wheel off when a ball joint is bad, and making a constant thudding that can be felt through the steering wheel when a bearing is bad.

Again, its the tiniest bumps, and wasboard sets it off the worse. Doesnt matter if the wheel is straight or turned, and big bumps dont do it, everything feels tight and sounds great over speedbumps and potholes. Im at a total loss here, any help would be great.

Double-check that everything you've done is still tight...with a wrench, not just by wiggling it. Also, consider control arm bushings...they can cause the noise you describe.

If the IRO CAs have the adjustable flex-joints, make sure they are tightened to IRO's specs. Slightly loose, they can make hard to find noises.
I had this problem with a new RE Super-Flex joint. It felt tight but the noise continued until i bought the proper tool and wad able to crank the adjustment down hard.
Noise eliminated after a couple months of head scratching.
The IRO flex joint appears to be constructed similarly to the the RE Super-Flex joint.

Tape a camera to various suspension parts and record. I used a tripod taped to the control arms and screwed my camera onto it. Works best if you have a unidirectional mic but will work okay as long as you can see/hear the noise in synch

Jam nuts?
Shock bar pins?

I hooked up the gopro at several various spots. Not one peep of movement. Im running to harbor freight, thats the one thing i never retightened, the seat nuts on the LCA. Good looking on that one, ill report back to see if thats it.

is the noise obviously louder anywhere? i found a squeak from the transfer case front output bearing when I taped the camera to the crossmember

Ok, i narrowed it down but i ran out of time today. I recranked everything, and i mean everything, to no avail.

I have to take the wheel off tomorrow and dig, but when i drive her with the brakes on the noise is gone. Nice and tight. Let the brakes off and rattle rattle rattle.

Before i get her in the air again tomorrow what should i be looking at in this case? Seems like the rotor is just loose.

Thanks again for the help.

It's not the rotor.
The brake pads are a poor fit to the steering knuckle.
Some brands, I think I recall "Centric" here but not sure, come with varying thicknesses of shims that hold the pad in place snugly on the knuckle's pad supports.
Otherwise, look up "XJ weld knuckle repair" or similar.

Rotor is held on by the wheel, it better not be loose. Actually could be loose lug nut or something though.

If its the brakes its probably the pads rattling on the knuckle. You can get some anti-rattle clips that will stop the caliper from jiggering around, but if the knuckle is severely worn / grooved you will need to repair or replace

Well, i ended up taking the wheels off, and the pads are snug as bug in a rug......

But, i confirmed that there is play in the U shaped knucle that holds the ball joints. They are shot completely, the bolt moves up and down in the balljoint itself, both sides.

Now, anyone in Colorado have a saturday afternoon and a balljoint press?

Ill bring the beer, 420 if applicable, parts and pay at least 1/3 of what a mechanic would charge. Would help a bunch.

I know this is a simple job, i just dont have the press, 4wd adaptors of the space to do it.

The upper ball joint is meant to slide up and down. It's basically a spring loaded centering pin. The lower ball joint is a true ball joint and should have no up and down play. Where in Colorado are you?

I think i may have found something....let me know if this could cause it, because from what i found this seems like the kind of sound im hearing....small bumps making it sound almost like both wheels are loose.

I noticed today my one coil spring ratainer clip was broken in half not holding anything down, and the other side mist have fallen out, theres no clip or screw (these were definitely in place when i lifted her, they were brand new and came woth the springs)

Could this cause the noise ive been describing?

Its so hard to describe noise in a post obviously, but its the smallets cracks in the road that set this noose off, cracks that dont even compress the suspension one iota, but cracks that jostle the wheels. When the suspension compresses over a large enough hole or bump, no noise.

Mine did this when i broke my LCA bracket.Look for cracks around all the mounts if it still does it after you re tighten everything

I was able to get video from every angle and every part, from sway bar links to struts to exhaust to even the brass bushing in the shift linkage. Ball joints are fine, nothing moves. Everything is brand new and tight. I can hear the noise in all 9 videos, but i cant trace it down to a part. Seems like the video of the shift likage produced the most boise, but still no pinpoint.


Question: CaN tired by any chance mmake any similar noise? My BFG AT are really cupped up front and almost slicks, possibly belts inside seperated?

Im running out ideas on this one. I know its a jeep, and they are noisy, but this isnt right.

You might look at your springs hitting the frame.
It happened to me so I zipped tied some rubber tubing on the spring.

Loose wheels would make a wobble.
BFG A/T make tire noise that some people may mistake for a bearing going out.
You can rotate front to back and see if the noise changes.
I have never had a tire clunk. Broken belts tend to me more whop-whop-whop like in my experience.
For problem isolation you might try driving without your sway bar. Just don't go fast around corners. I know you said you changed the bushings but possible the new bushings at the frame rails are the wrong size.
Also, maybe have a look at the track bar again? The TRE at the end can making clunking and popping noises though I've only ever had it backing up from a parking space, not going down the road.
And check the exhaust mounts.
How much space is there between your exhaust downpipe and the transmission crossmember?

Ill try disconnecting the sway bar to see if anything changes.

The Track Bar is a double shear, so No TRE on it. Shes super tight.

Not the sway bar or links. Disconnected today and noise still there.

Noise isnt a single clunk either, it corresponds with the road, like a rolling rattle.

Going crazy here.

Thabk you Mike for the help today, we confirmed its my ball joints. Buggers.