I just got a 2008 F150 Crew and there a noise when your on a rough road [small potholes} it sounds like something is hitting bottom of the box or the back of the cab.We have checked everything cant make it go away . Could it be a bad shock? it only has 73000 miles on it the guy says you may have to unhook the shock and see if it goes away.Is there any other way to check it out?

 

That's a lot of miles for original shocks. Either way, I'd replace them whether they're the culprit or not. Check the leaf springs too, you could have a broken leaf.

Removing the rear shocks are easy. You don't need to even remove the wheel or lift it off the ground.

 

pop in bed liners make noise on bumpy roads sometimes!

 

Was the spare tire carrier checked as well?
Also, agree with 2008 xl, that is enough mileage to warrant changing out shocks and struts if it hasn't been done already.

 

There are lots of pieces back there that can cause the symptoms the op described. I had a thumping that sounded like something sliding around in the bed which turned out to be the rear bolt through one of the leaf springs needing tightening. His problem could be caused by shocks or other suspension parts, spare tire carrier, exhaust system, or a loose frame damper among other things.

 

Noise still there after 4 mo has new shocks have checked spring bushings Brake cables fuel lines cant find a thing. It went away for a month then came back.. doesn't do it on every bump. but it still sounds like something is hitting floor of box or cab or back of cab

 

After 6mo of chasing a noise I may have found it. I have about 300# of bagged cement in the back of the box. Noise seems to be gone, are the springs bad? doesn't sag. Any ideas would be helpful
Thanks

 

I'm interested as well. I have the same thing. Everything's tight, replaced shocks, temporarily zip-tied the spare tire carrier (I don't carry a spare). I'm subscribing to the thread in case anybody comes up with something.

 

Ive ordered new rear springs, hope this fixes the noise

 

Let me know if it fixes it. I have a set lined up so if you say it works, then I'll run out and grab em.

 

Problem fixed new springs were the answer. Now I have a slight vibration at 20mph i'm thinking I need shims installed I didn't notice it until I lowered the rear with shackles

 

I don't understand how some trucks require the shims and others have no vibration whatsoever. Glad you found the fix though!