above 70mph vibration

[dpmeeks]

As the title says.. im having a vibration only at above 70 mph. Here is a list of repairs ive done that were needed and or trying to fix this problem.

- New pass side cv axle
- New front wheel hubs
- New front wheel hubs
- New motor mount
- New Trans mount
- New front tires ( balanced and re-balanced )
- New outer tie rod ends

I had the new tires on the front and after having the re-balanced I rotated them to the rear and im still having the issue.

Any ideas on where to look next ?

 

[Turbocharged400sbc]

just to make sure it isnt a misfire issue, next time you duplicate it, use left foot to move brake pedal just far enough to turn on brake lights. this will kick the TCC off and engine rom should rise and engine load will go down. if the vibration diminishes or goes away its likely its a misfire under high load, possibly worse on humid or wet days. if not then its driveline related or likely the road. retest on other roads. lots of roads get washboarding

 

[dpmeeks]

Ill try it.. I just dont think its a misfire. It only does it on the highway so its a speed related issue.

 

[Turbocharged400sbc]

Ill try it.. I just dont think its a misfire. It only does it on the highway so its a speed related issue.

or since in 4th at low rpm, your loading the engine down far more than at any higher rpm.

this would be far from the first time ive had a vibration that was a misfire starting. even if they thought we were full of **** and took their car...they usually end up with a tuneup in the next month or so after a wet day.

way less load on the engine in all other gears than overdrive.

 

[dpmeeks]

I agree and that makes sense.

 

[FordMan77]

How are your brakes? Not saying it's not a misfire, just thinking outside the box. If you have a rotor or 2 that is warped it may show up at higher speeds.

 

[koRnhead]

Drivers side axle?

 

[dpmeeks]

Ive ordered new brake rotors i was thinking that too. My drivers axle is like new. I removed it and repacked.with grease.