Knocking underneath when off roading

[Michael Roberson]

06, bone stock 4.0, Dana 44. While on a trail today, nothing treacherous but some deep trenches, loose rock and mud puddles a car shouldn't go through, I noticed a knocking sound when I ran over some obstacles. Someone give me their thoughts. Something is loose, just not sure where to start. If I had to pick a side, I'd say passengers. But I can feel it pretty good. My buddy in front of me heard as well. It seems to happen now when I bounce through smaller obstacles like railroad tracks. Help if you can.


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[Rob5589]

You have to start checking everything under the Jeep, under the hood, etc. Could be all sorts of stuff.

 

[Jerry Bransford]

Do you have shackles mounted on your bumpers?

 

[Michael Roberson]

No. No shackles. Truly bone stock. It almost sounds like my skid plate is loose but it doesn't feel loose.


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[Michael Roberson]

You have to start checking everything under the Jeep, under the hood, etc. Could be all sorts of stuff.

I'm still trying to check it. It's hard to tell it drives perfect on a paved road.


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[Michael Roberson]

No. No shackles. Truly bone stock. It almost sounds like my skid plate is loose but it doesn't feel loose.


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Maybe the Kentrol bumpers are not bone stock but the specs are.


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[WWII Jeeper]

I had similar on my 06 TJ X, it turned out to be loose exhaust header to manifold bolts, which made the entire pipe system loose, and the rear exhaust pipe was rattling up against the frame and my fuel tank plate (side).

Ray

 

[Michael Roberson]

OK. Yea I can look at that. Didn't cross my mind.


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[StG58]

I've been watching this thread since it popped up. (and thinking about it)

There are a lot of parts in close proximity under a TJ. Most of them can get loose and make various rattles, squeaks, groans, moans and whistles. It's a pain in the ass to chase any of those down, but we are subjecting our rigs to conditions that automotive engineers (even the ones at Jeep) would find extreme. That's going to cause broken or loose parts and noises. The best way to combat the broken parts and noises is to crawl under the TJ on a regular basis and lay your hands on her. Push, pull, shake and look for anything that is amiss. Put a wrench on the nuts and bolts under there and make sure that everything that needs to be tight is tight and / or moves the way it's supposed to. It's normal maintenance for vehicles used off road, or in any harsher than usual conditions. It's what happens to almost all of the vehicles that you hear about that never seem to break down. The reason they never break down is because all (most) of the issues get caught before anything breaks on the trail.

The upside to doing that is you will see where the problem areas are before they become issues and you can address them before something breaks.

 

[TJ4Jim]

Could be a toasted transmission mount.

 

[Michael Roberson]

Seems that it's my passenger side sway bar link bushing.


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