I have a 97 F150 SUpercab XLT with 75K miles.
When I am easy on the pedal, I get a vibration at 39MPH and again at about 65-70MPH (especially when I pull my boat)

The vibration is rougher at the higher speed but at the lower, it feels as if I am driving over those "wakeup" bumps on the side of the highway. The vibration is brief and goes away.

-Could it be the tires?
-Mechanic told me yesterday that I need the ball joints replaced on the left side, inner tie rod on the right side and a front alignment. Could any of these parts needing replaced have anything to do with this vibration?

OR
Do I have a different problem that causes these vibrations.

ANy clues would be great.

Studog

 

if it were tires i would think it would be a constant shutter. same with bearings. what i'm thinking is...what changes from one speed to another.....transmission. you said it's worse when towing boat....bigger drag on tranny. for what its worth, had same problem on a van ...... torque converter in tranny.

 

oh that's not good news at all. I have heard some say to change the fluid to stop vibration. What's that got to do with it...seriously don't know?

Thanks

 

don't mean to be a wise a$$......changing the air in the tire won't stop it from cupping or bulging.
i wouldnt tow with it until you get it checked out.
go to a couple of places and describe the problem...don't tell them what you think it is.
i found the best way to find a reputable mechanic is go on the advice of people you know and trust.....friends.

 

The first thing I always check for a vibration is the driveline u-joints. I have had a number of them go bad in my jeep. It starts with a slight vibration, and is load related. Good luck.