Can't seem to find out where the knocking noise is coming from on my 1991 F150. The noise isn't coming from the engine or transmission. The sound is like a rock in the tire but no rock. I have no idea where it is coming from. Only othere info that i have is that i can hear it from the drivers side. Any help would be apprecitated.

 

I think I may have an answer for you. Your problem sounds just like the one I chased. Turned out to be my caps on my wheels! The centers of the wheels are a little larger than the caps making for a sloppy fit, thus the nocking noise.

 

Thanks will check it out and let you know what I find out