just bought a 05 fx4 and was driving home tonight and noticed a slight vibration around 50mph after shifting into overdrive and light throttle, almost like driving on a rumble strip or a driveshaft out of balance. this is the only time it makes the vibration is in OD over 50mph giving it throttle. Any ideas or am i just paranoid??

 

I just added some new tires/wheels and get the vibration between 50mph-53mph. I'm guessing it's my wheels needing balancing?

But now I'm thinking could be drive shaft too.
Can anyone tell if there's a different feeling between the two?

Original poster, have you recently replaced your tires or rims? Could be an off balance wheel weight?

 

mine isnt that bad. just a slight vibration, can be felt most in the center console lid.

 

and also, when i let of the gas when going 50+ the shaking stops

 

Are you sure it isn't an engine misfire?

 

I would get the tires balanced, cheapest and easiest thing to try first

 

the dealer i bought the truck from put new tires on and balanced them, doesnt feel like a tire issue. look under the truck a bit ago and the only thing i can say is out of the ordinary is the driveshaft has some play in it where it goes into the TC, very slight, but it does move up and down in there.

 

Okay drove it some more on the highway tonight and it shakes like on a rumble strip or driveshaft out of balance only around 50-60 mph or 1400-1700rpm. If you let off the gas in that range, the vibration stops. Any faster or slower and it rides smooth.

 

My '03 does the EXACT same thing. It does it almost on command...right around 50 mph if I'm letting of the gas coming to a stop light or appraoching an exit ramp on the highway and then getting on the gas again it does that vibration. I'm not even punching the gas, just slowly easing back into it and it'll do it.

I've been searching for the issue and it seems a lot of guys have the same problem. I've seen u-joint wear as a possibility.

 

My 04 was doing the same thing at 45-50mph in OD. It ended up being a low grade misfire. Hasn't done it since I changed plugs 13,000 miles ago.

 

well the truck goes into the dealer tomorrow for the clock-spring recall, gonna have them check it out and see what they think.. tryed pulling codes tonight to see if there were some stored, none showed up. been bugging the hell out of me as im in college and dont have the funds to start throwing parts at it. gonna see what the dealer has to say about it, but planned on changing COPs and plugs this weekend. also need to change an axle seal on the right rear, fluid level is good though so i dont assume that is my problem.

 

make sure to tell us what the dealer found

 

just got it back from the dealer. tech said he drove it and it isnt missing. suggested a bad u-joint. told me to rotate it 180* and check it. just doesnt make sense that it would only do this while on the gas, once i let off and coast it is smooth. he said it was not a misfire though.