You won't believe this...read whole story pls
1999 ford ranger 4.0 v6 4x4 with 217,000 miles. Ok here goes. I turn on truck, runs great, i drive, runs great, then suddenly for no apparent reason there's a BOOM and it feels like something dropped and the truck starts vibrating and sounds/smells like the tire is hitting something...so i slow down as fast as i can. when i drive again EVERYTHING is back to normal, THEN BAM! again! like something dropped, lotsa vibration. truck does NOT lose any performance, steering does NOT act up. NOTHING changes cept i can smell burning rubber like the tire is hitting something. And it WILL NOT stop no matter what speed i'm going no matter if i slow down or speed up it WILL NOT stop UNLESS i bring the truck to a COMPLETE stop. then, voila, problem is gone! until it decides to come back. problem happens at various speeds, but usually above 45mph, but then as i slow it DOES NOT go away unless i come to a complete stop. then it starts over. i have no freaking idea what this is about. tires are a little old, but wouldn't the problem be there always if it was a tire? engine mounts are problem old, but again wouldn't the problem stay all the time? and the tire burning smell, i cannot find anything to indicate it's touching the tires. entire front suspension has been replaced and looks tidy. engine mount sounds most likely but why the rubber burn smell? and why does problem persist no matter what unless i stop? it makes absolutely no sense to me. i've looked up all kindsa vibration problems, and most make sense. it happens in neutral, or at a certain speed, or gets worse as speed increases. my problem exhibits NONE of those! it comes on fairly random and then persists until the truck is stopped, no exceptions. WTF can make this happen?