My truck started bumping (like it is going into gear) from a dead stop about 6 months ago. I have checked everything external to the trans that I can. Today I thought about foot braking and accellerating. It seemed to shift into gear with a bump, I let off of the gas and brake and accellerated normally, and it did not bump. Does anyone know of similar problems with this type of eng/trans combo (4.6 Auto)? I do service the vehicle well, and the trans shifts great after it starts off. Any help would be appreciated.

 

Gregg
Are you sure that it is the tranny? Could it be the slip yolk on the drive shaft. This is a known issue for ford trucks. I thought I had a bad engine mount or something on my 06' 2wd. On mine the bump only happens from a stop. Leaving the line the truck squats shortning the drive shaft at the yolk and at the same time you are appling torque, the result is a momentary binding and release(bump). It is not like a slipping tranny has a very solid feel to it. Hope that is what it is on yours. If you look at the shaft there is the area with a rubber boot that is where I had the issue. I dropped my drive shaft from the rear diff with the intention of greasing mine, but could not figure how to get into the thing, I stroked mine back and forth a few times to spread the existing grease around and bolted it back up (4 13mm bolts). The problem disappeared for about 50k miles. now it's back but I know what it is and it is not a big deal.

 

Yeah that sound just like what mine is doing. I'll check the slip yoke and see what I find. Thanks a bunch.
Gregg