Ok here we go. I have just bought a extend cab 99 with a 5.4 4x4 with just under 180k motor was just replaced with new ford crate good deal right wrong. The truck need a trans so I swapped out the trans out of my standard cab (also a 99 5.4 4x4 ) all is good .Not just more than two hundred miles rear end takes a crap replaced all bearings and new seal and axle on passenger side. Also replaced both ujoints. Alls good nope now I have a vibration at around 45/on it gets worse at high speeds but here the I'm stumped and need help the vibration moves from the steering wheel to the seat and all around the truck.it is vary noticeable at 64 mph any one got any ideas?

 

Loose lugnuts? Out of balance driveshaft? Bad tire or tires? Engine missfire? Slipping transmission?

 

Did you buy a new torque converter when you put your other tranny in? Or use its TC. How were the tranny mounts when you did the swap? If they are original, they should have been replaced as they can cause vibrations. Also, I'm sure you have the LS rear diff, was friction modifier used?

 

Yea, I only had that problem when my modifier/fluid broke down in the rear end fluid. They'll do that without Modifier in an LS rear end.

 

Could be front wheel bearings too I had a heck of a vibration at 65 with bad bearings. Is there any noise associated with the vibration or just the vibration itself?

 

sounds like the driveshaft is out of balance. I had the same problem when i replaced both rear u-joints and didnt mark the yokes.

 

ok i have had the drive shaft balanced and yes i used friction mod in the rear end it is a ls 3.55 in the 9.75 rear also replaced the u joints new trans mounts. But did not replace the tc the trans shop that i brought my old trans to to go throug said it was still good seems that the drivers side wheel seal is leaking and thats my fault will replace it along with new bearing and axle .



why is it when we have money nothing breaks but when we are broke everything breaks ?

 

Replaced wheel seal and new axle and bearing the vibration is still there ? anyone got any more thoughts on this matter.

 

Have you went to a tire shop and have them balance the tires? could be that or maybe a broken belt in a tire.

 

Wheel bearings? I had a vibration from 45-55 it was really noticeable. Jack up your front end, grab the top and bottom, and rock it in and out. If it moves, thats probably your problem. Replaced mine, vibration went away.

 

Yes have had them balanced and they said all was good . I know that the tires and wheels are not the issue. they came off my reg cab and i never had any issues with them. thanks for the thought

 

I thought that could be it but the front end shop said all was good

 

Not sure about 4x4, but on the 02 4x2 there are two bearings on each front wheel. Inner and outer. Did two trucks last year and had to redo one because the new bearing went out. Would have ruined the spindle if we hadn't caught it when we did.