There is a big thread on banging in OD. It focuses on a misfire causing this. I experienced something different.

I have In '03 XLT FX4 5.4l 4R70W transmission. I was experiencing a pretty hard bag when driving around 50 mph. While doing other work I dropped the transmission pan and valve body. I replaced the separator plate with the heavy duty one along with all the ***** and the OD servo. I did not replace any solenoids.

This did result in a smoother shift. I did see today that the fluid level is a little over he high mark but not past the plastic on the stick. This was checked while plenty hot being a 9 hour drive. On the road so the fluid level will need to wait.

Today while driving down I81 i set the cruise control at 75 mph. It held a steady 2100 rpm but when pulling a longer uphill grade, it would jump to 2400 and did a slight "bang" on this shift. It seems like the converter was unlocking. I saw that if I turned off the OD it really slipped before it settled in. Aside from this it really ran great.

My Towncar (same trans and gears at 3.73 but has a 4.6) does not have a tach to watch and it has no bang whatsoever. I even increased the pressures through the tune on the Lincoln. My Chrysler has a lockup converter, but dont believe it unlocks in 4th or 5th. Should the converter unlock in the truck? Is that what is happening to jump from 2100 to 2400 rpm? Could the fluid being high cause a rough shift?

 

So.... no one knows about the torque converter?

 

It's usually applies around 1800-2000 from the factory, but that is under a light load. It really depends how you are driving it. It feels like another gear... it will drop 300ish rpms.

My experience with OD and a misfire has been an in and out experience. It can't decide if it needs to be in our out of OD. No "bang", more like a mild clunk.

 

Great info! So, it is just over 2000 rpm but does the 300 rpm jump. It is OD, so i guess the converter is unlocking when under the stress of a long grade. I guess this is normal.