When I'm driving my 1990 Ford F-250 (8' Bed Model) and I hit a bump in the road or something, the rear end makes a loud "BANG" noise like there is something metal in the bed that is bouncing up and down, but there isn't.

Does anybody know what could be wrong ?

 

I'd check your suspension, it sounds to me like the weight of your body and frame is hitting the axles/suspension...

If you have rear endlinks/sway bar with old rubber bushings you can get a pretty decent clunk when the beds weight slams back down on bad bushings... ie weight hits down on endlinks instead of the bushings. Also check your shocks and leaf spings and all associated bushings.

here is a link to my "how to" page with pics from when I did all my front and rear suspension work. While ur under the truck look for obvious things like muffler hangers that are busted, busted shock mounts, etc...

https://www.ford-trucks.com/forums/1...with-pics.html

 

I'll go out and have a quick look at things and see if anything looks out of place. I'll update it when I get back.

 

I can't see much wrong to be honest. There is a lot of rust under there, but I'd need her up on a ramp to really have a good inspection.

 

I was getting a constant "thud" sound from mine before I fixed the rounded out eyelets (see link I posted b4 for pics of eyelet problem). The eyelets are a problem that is harder to see... the other thing you might try is jump up and down in the bed... I know... sounds childish... but if you can create the sound without running down the road that means you can block up ur truck and slide underneath to find the source of the sound while a buddy jumps in the bed... LOL...

 

Ha ha, I may try that one.

I did think for a second maybe the noise was the dead body I have strapped to the undercarriage, but he is still tightly strapped in

 

sounds stupid but that's how I found the rounded out eyelet problem... noticed the shock going up and down and not compressing...

 

Have you tried lifting upwards on each corner of the bed? Your bed bolts may have backed off/broken/pulled through.

 

You'd have to have a really really rusty bed, frame or bed bolt to do this... The way the bed bolts are sleved inside the bed frame and are welded to the top and bottom of the bed frame itself would be hard pressed to break not to mention we're talking thick **** bed bolts...

But non-the-less probably worth looking into...

 

So try lifting the corners up and see if they have slack in them ?

 

Is your exhaust secured tightly? Maybe the whole exhaust bouncing and hitting the bed/frame somewhere.....

 

If its a loud bang Id think the rear most spring hanger and or shackle has rusted out and its sitting on the bed. May have been said/checked already...

 

That why my first thought--those spring shackles are known to not last forever, particularly in the Rust Belt of the country. I've seen them let go in trucks much newer.

Jason

 

Good call... Guess I was more general about taking a root around under the truck but the shackles were among my first thoughts along with exhaust...

yep... or if under the truck you can use a foot to push the bed up and watch the bed bolt nuts from the bottom... Last thought would be to have a friend ride in the bed and listen to isolate the sound left to right and front to back... At least that way you'd know a general vacinity to look under the truck and would rule some things out.

Let us know what you find, when you find it! I'd be interested to hear what it was and maybe see a pic or two!

 

I haven't had a chance to look any further into it yet, as the truck has been in almost daily use hauling things around, but I'll take a look soon.