Knocking sound in rear. Checked everything I’ve found in threads. I’m lost.

[eric_simmons]

I’ve been chasing this sound for YEARS and cannot locate it. Looking for some ideas of things to check.

2002 Limited

Symptoms

• Knocking as I go over bumps.
• It sounds more like something is loose because it will happen even over small bumps such as manhole covers, road seams, small cracks, etc.
• It sounds like it’s coming from the driver rear wheel well area.

Already Checked

• Spare tire is snug and sound still occurs when it is removed.
• All new suspension put in two days ago.
• Brand new sway bar end links and bushings.
• There is no play in any of the arms (control, panhard, etc.)
• I have gone underneath with the spare removed and gave everything I could see an attempted shake and haven’t found anything loose.
• I removed the interior drivers side panel to see if something was loose. Didn’t find anything loose.
• Body mount bushings are likely original, but it doesn’t seem like it’s that.

Jumping on, rocking, or shaking the vehicle does not replicate the sound. It only happens when the vehicle is moving. It is not related to speed or anything.

It literally sounds like something is lose and just knocking around even as I hit light those light bumps. It doesn’t seem suspension related.

It’s driving me mad, especially with having replaced my suspension because it still sounds like it bottoms out and I just want to enjoy the cushy ride without clunks and knocks.

Help!

 

[GhostRing]

You said the control arms have no play, as in - you removed them and checked the bushings on the bench?
If they are the original 22 year-old bushings, I would be amazed that they are still in nice, fresh condition.
It is totally worth replacing them just in case. Check your gas tank skid plate and confirm there's not a
rock bouncing around up in there. Also make sure your sway bar isn't contacting the e locker cover plate.
I've also run into the transfer case damper weight's rubber being toast and allowing it to rattle.

 

[3bears]

You said the control arms have no play, as in - you removed them and checked the bushings on the bench?
If they are the original 22 year-old bushings, I would be amazed that they are still in nice, fresh condition.
It is totally worth replacing them just in case. Check your gas tank skid plate and confirm there's not a
rock bouncing around up in there. Also make sure your sway bar isn't contacting the e locker cover plate.
I've also run into the transfer case damper weight's rubber being toast and allowing it to rattle.

agree with all this, and if your lifted with an elocker you should have to get the rear sway relocation kit or your sway bar will hit. Sonoran Steel

 

[brillo_76]

If all that checks out good. We had a knock in the rear of the 1997 limited. I checked everything was in the rear compartment area. Ended up being the bottom of the rear window rail rotted off and was banging around in the rear hatch.

This would only apply in the rust belt though..

 

[eric_simmons]

I appreciate everyone’s time and suggestions so much.

I checked a few of the things mentioned with no dice.

Control arm bushings certainly need to be replaced, but it wasn’t that and that is added to my super long list of things to do.

With the back panel removed and after checking everything, I had my girlfriend drive around while I sat in the back and listened/felt and isolated the source to the rear driver corner near the body mount.

That gave me the idea of jumping on my hitch to seperate frame movement from body movement and I was able to recreate the sound. Turns out it was my bumper smacking off of the hitch frame. Someone smashed me in a parking lot (and left �&#56900, which I guess messed my bumper up enough to move it downward slightly. So every time the frame moves it hits off of the bumper, creating the knocking/rattle sound.

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I tried to bend just that part of the bumper up with a prybar just to create a bit more room between, but it looks like I’m going to have to take the bumper off and maybe cut out a little slot for the frame to go into so I can get rid of this damn noise.

Any other suggestions that wouldn’t require me removing the bumper?

 

[Twisted Sid]

How/why is the bumper that loose and floppy? Even being slightly hit by someone, it shouldn't move like that.

 

[eric_simmons]

How/why is the bumper that loose and floppy? Even being slightly hit by someone, it shouldn't move like that.

I imagine it’s the 22 year old body mount bushings needing replacement. The pins/bolts on the rear have a fair amount of movement during this. So it’s not solely the bumper but the whole body. Another repair added to the list.

Gonna get this one over 400k &#55358;&#56606;&#55356;&#57339; and while I despise the naming of vehicles, definitely going to have to call this one Theseus in reference to the ship.

 

[GhostRing]

Everybody pays, that's how it goes...

pay through the nose for a new boring stock-as-hell car,
or weep cash into a cool, old rig that's unique to you.

 

[2TH4IST]

Yep as you know already, replace them body mounts bushings. I highly suggest going poly bushings. They will last darn near forever.

 

[eric_simmons]

Everybody pays, that's how it goes...

pay through the nose for a new boring stock-as-hell car,
or weep cash into a cool, old rig that's unique to you.

After that first line I was expecting a poem.

“Everybody pays, that’s how it goes
Get a new boring, stock-as-hell car, and pay through the nose.
Or weep cash into a cool, old rig that’s you unique to you,
Fix it yourself and you’ll be one of the pros.”

Or something like that. I’m not a poet.

 

[eric_simmons]

Yep as you know already, replace them body mounts bushings. I highly suggest going poly bushings. They will last darn near forever.

Looking into that as I type this and def going poly.

Looks like energy suspension is the go to. Wondering if I should also throw a 1” lift on to help create that space and because well… why not.

Doesn’t seem like there would be any other mods I need to do for a 1” lift.

 

[GhostRing]

After that first line I was expecting a poem.

“Everybody pays, that’s how it goes
Get a new boring, stock-as-hell car, and pay through the nose.
Or weep cash into a cool, old rig that’s you unique to you,
Fix it yourself and you’ll be one of the pros.”

Or something like that. I’m not a poet.

Hahaha!!

That was excellent!
I'll start working on my off-road haikus...

 

[2TH4IST]

Just be sure there are no stretched cables/wiring and you'll need to adjust the shift linkage. The front bumper is attached to the frame so you'll have a gap. There is a mod to fix it and I ran that way for a few years. It will be the body lift plus a steering shaft spacer.

I did th 1" lift years ago, to clear the f150 fuel tank swap. There are times it's awesome as it creates some clerance where it's tight....like the rear shock top nuts lol.

 

[eric_simmons]

Just be sure there are no stretched cables/wiring and you'll need to adjust the shift linkage. The front bumper is attached to the frame so you'll have a gap. There is a mod to fix it and I ran that way for a few years. It will be the body lift plus a steering shaft spacer.

I did th 1" lift years ago, to clear the f150 fuel tank swap. There are times it's awesome as it creates some clerance where it's tight....like the rear shock top nuts lol.

You trying to trigger my PTSD from those rear top bolts?! Haha

Honestly one of the reasons I’m going with the lift is because it comes with new bolts, where the bushings don’t. And looking at the old bolts I don’t think I’m going to get them off in one piece.

I didn’t see anyone mentioning adjusting anything else outside of the steering and front bumper mod. Is the shift linkage adjustment pretty straight forward?

 

[2TH4IST]

Yep very straight forward. Just loosen the nut on the shift linkage, unbolt the steering couple, then lift the body one side at a time, and tighten everything down.