Wobble/shake while maintaining speed @ 40 mph
 

My 97 4X4 F150 shakes while maintaining speed at around 40 mph. It stops shaking if I accelerate. By shakes I mean the whole truck moves. I'm baffled.

I had the left front hub replace two days ago which truly needed replacing. One month ago I had the rear universal joint on the drive shaft replace and a new left exhaust manifold. This is getting costly!

Any help from you fine gentlemen would be great.

Happy Holidays!
Nick

i had the same problem on my 97. if it is like a shudder at 40 mph,it is probably the transmission. i had the fluid changed and it stopped, no problems since then .sounds like thats what you may need. hope that is some help.

I had a 97 4.6 2X4 and it shook pretty bad when it shifted into overdrive. I think this was related to the torque converter or a dirty trans filter. You may want to have the fluid and filter changed. Since you may be going into it anyway, use a quality synthetic like Royal purple, or amsoil for the new fluid, just remeber to drain the converter as well.

Thanks for the advice guys. I'll get the tranny fluid and filter changed, including attention to the converter.

Merry Christmas