I have a vibration, shaking, or shudder coming from what feels like the rear of the truck, always at 30-40 mph. It begins at 30 mph and stops after 40 mph. It also does it now matter whether I am accelerating or decelerting and regardless of engine rpm. Any Ideas out there?

 

Sounds like you might need to change your transmission fluid, to include the fluid in the torque converter.

 

I'm getting this too at about 50- 60 mph.... stops after 60.

If I switch into neutral and coast it stops....back in gear it does it... like kdillard21 said whether acc. or decel.....but not coasting in nuetral.

I thought I was imagining it but its starting to bother me now...

I feel it in the wheel, at my feet, in the seat...
Feels sort of like a u joint going bad.

kdillard....does this sound like the same thing?

Anyone else??

 

yeah that is what i get, but what about the big difference in speed? I only got 73000 miles, U-joints go bad that early?

 

When I replied to this thread I thought I was still in the 2004 F150 forum....

I only have 500 miles on my truck...

You, on the other hand, could very well have a bad U joint.

I reposted this in the 2004 F150 forum and had another response from a 2004 owner....that the dealer put shims on the driveshaft for balancing.
His was at a lower speed too

Could very well be what my trouble is.... when I saw your post it described exactly what I feel....it's not excessive, it's slight. It wasn't there for the first 200 miles....it's there now and it's annoying .