I noticed when towing or with a heavy load in my bed i get a lot of squeaking or strange noise. I towed my 23k lb trailer yesterday, dropped it off, then put some heavy stuff in the bed. When i was unloading standing in the bed, it was making a creaking sound. I started jumping up and down looking like an idiot to find out where it is coming from. It seems to be coming from the drive side rear. I unloaded the bed, jumped some more, and it was not really doing it, unless i jumped around hard on the very end of the bed on the driver side. I got out took a flashlight (night time) and looked under the driver side rear, right infront of the bumper i spotted a large metal circle, with 2 rubber ends on it. And the rubber end on one side is totally cracked off, and the other side, almost cracked off. I assume this is what is causing this sound, my thing is, what is this damn thing? I looked on the passenger side and there is nothing there. So whatever this is, why is it only on the driver side rear?

here is a pic.... (please ignore my sloppy wiring job, those wires go to a reverse camera i recently hooked up).

 

I have no idea! I will have to see if I have that..or I wonder if this is F450 item only.

On edit. I think they may have to do with the rear springs.

 

see if you can identify it here

 

Scott! come on! i was relying on you! No, i cannot find it there, it seems like if it was from the other side i can... it is very weird... Maybe it is an F450 thing? I am gonna bust out the service manual and see if i can locate it there...

 

I looked at this some more again. It is not connected to the suspension. It appears it is some sort of bump stop for the bed? not sure, but it looks like something like that. I am probably totally wrong. I looked in my service manual under suspension and under pick up bed, and found nothing!!! Still need help!

 

That's a vibration damper. Part #5D008. Only in 450 and 550's.

 

Darn it! RM beat me to the answer.
2X on the damper.

 

Wow! thank you!!!! What exactly does it do? and i am guessing this is what is causing my sound i hear with a loaded bed?

 

It helps to adsorb vibrations in the tail end of the frame.
http://en.wikipedia.org/wiki/Tuned_mass_damper

Spray it with some silicone lube to see if the noise abates.

 

The rubber in the unit has been severely damaged from what the OP has stated. It most likely could just be removed so it doesn't cause the noise. Replacement seems to be somewhere in the $400 range unless you can find an aftermarket.

 

$400!!!!!!!!!!!!!!????????? WOW!

I wonder if this is replaced under my extended ford warranty?

Yes, mine the rubber is totally cracked and spray i cannot see helping.

I still somehow do not understand how this thing works, it almost appears to be connected to nothing? i am tempted now to see if i take it out if it still makes the sound? also curious why only the F450 and 550 have it...

 

I'm guessing it's only on the 450 & 550 to help with the larger loads. The full name from Ford is Suspension Subframe Vibration Damper. So under heavier loads, the suspension most likely vibrates more requiring this part.

I would assume that it's covered under Ford X warranty.