I have a 99 f150 that experiences a strange vibration betweek 5 and 15 mph. It has a new transmission, new spark plugs, new tires (not the balance of the tires, I tested it), new shocks, new air filter, new egr valve and solenoid. Cant seem to find out what the problem is. Any one have any suggestions? All thoughts appreciated. Thanks.

 

wut kind of tires did you put on? aggressive tires can vibrate the truck at these speeds. my procomp x-terrains do.

 

Have you checked the U-joints? When mine went bad they would only vibrate at certain speeds/rpm's.

 

I checked the u-joints and they seem to be ok, but I do have an aggressive tire on it. They are 35" Nitto Grapplers... do you think that would do it?

 

It may be the U-joints or perhaps the drive shaft has become unbalanced. I had a vibration in mine between 80-100 Kph. Turned out it was a bent/unbalanced driveshft.