Has anyone heard a "thunk" that sounds like it's coming from behind the driver seat when you suddenly stop harder than normal either in reverse or forward? I notice it happens very rarely, and that it never happens twice in a row going forwards or in reverse; the sound alway alternates with the change of direction, as if something was rolling forwards and backwards. I think it might have something to do with the seat belt counterweight, but I can't make it happen when I want, so I'm not sure.

 

This may sound crazy, but could it be gas in the tank? I've had this happen on both pickups that I own (both with ~20gallon tanks) and at certain fuel levels and after certain stops, there is definitely a thunk from the gas sloshing around. Typically it happens a fraction of a second after the stop, and is a low frequency, dull sound. You can even feel a slight shudder as if a couple milk jugs have rolled into the car.

Just a thought...

-D'oh!

 

man your all over it today beat me again..

um how bout a soleniod firing?