Washboard effect?

I'm pretty new to this newsgroup and I saw a previous post about something
about a washboard effect. It was for the 2002-2004 model year transmissions.
I was wondering what the washboard effect is, could someone explain it to
me. I too have a 2003 explorer 4.0 V6, so I was wondering what it was.
Thanks for the replies.
George

The term 'washboard effect' has been used on another group to describe the
vibration caused by torque converter shudder. Common wisdom claims that the
TCC in the 4R70W transmission (not the case for a V6) is prone to this, and
the problem is easily cured by changing fluid.

Something akin to this just happened to my '98 V8. Noticeable vibration at
about 45MPH. Goes away when I switch the O/D off, engine idles smoothly, MIL
off, no stored DTC's. Must be the dreaded torque converter shudder, I
figured. The transmission fluid had over 20,000 miles and was already
discolored, so I bought a case of Mercon V and put it all in (yes, I did
drain the old stuff first), hoping for this 'standard cure' to work. The
only effect was a very slippery garage floor... Finally, the little orange
light started flashing, and a code for cylinder #8 misfire was stored. Yep,
another ignition wire gone south, not that long after installing a whole new
set (which came from the pretty orange $100 OEM box, not some aftermarket
cheapie). What puzzles me in this story is why the original ignition wires
in my '85 LTD are still in perfect shape after 20 years and 200,000 miles.
Lower voltage? Unlikely, as the LTD plugs are gapped the same as in the
Expy. Perhaps the ignition wires just do this to show sympathy for the
disappearing display in the fancy MACH radio? Or are they programmed to fail
soon after the DPFE goes? Go figure...