Readyt

My 1998 F150 5.4, 4X$ just started to shake or shudder when it shifts, speeds up or slows down. It can be felt strongly through the seat and more pronounced at 45 MPH. I checked:

1. U-Joints- Firm and Solid
2. Felt like a broken Engin Mount- But when brake tourquing the engne desn't budge.
3. Dealer said it could be a tranny mount, but not a u-joint?????

A little bit of the shinny part of the drive shaft "Yoke" can be seen out of the tranny.
Any ideas?
Thanks
Ted

NGM

Try servicing the transmission and adding a good trans addative. If that dosen't fix it its time for a rebuild. The Shudder is the clutches slipping or the torque convertor slipping excessivly.

obusnizzle

sounds typical of convertor shudder in a 4R70W. Drain the fluid in both the convertor and pan, change the filter and add the requisite amount of MerconV..yes MerconV, not plain Mercon, not type f, MerconV. Its a semi synthetic that was engineered by certain Ford Powertrain engineers, one of which started a little company called SCT...anywho, its generally considered a not so wise idea to add some kind of additive to modern Semi Synthetic transmission fluids...Why? It may have been a good idea 20-25 years years ago when transmission fluid was made from a base of either hog or whale fat, but not so much anymore.