That sounds more like the kickdown to me too.

 

To me it sounds more like a low fluid level. I would absolutely check that first.

It has to be warmed up, engine running, trans in park to check the level. If you check it with the engine off, it will read wrong.

The modulator is an easy, cheap change, but most of the time its the hose to the modulator that fails. Check that too.

Other than that, go thru the troubleshooting steps. The 400 is a very rugged transmission and not prone to sudden failure unless it was severely abused.

 

Ok guys, this is what I have found and done to this point.

First good news the car drives and shifts through its gears again, YES!

I ended up dropping the pan and since I had it down and everything looked good I installed a transgo shift kit in it.

After I dropped the pan, it was mentioned in previous posts that the problem may be the micro switch on the throttle linkage. At first this didn't seem logical to me but after dropping the pan and finding clean fluid and no metal chips to speak I began to reconsider this. Remember I was doing all of this very quickly.

I paused to think about it and thought about my test drive and how I put the car through its paces which included pedal to the floor, Then I thought when was the last time anyone floored this car?

So with the pan still off and the shift kit in the mail I looked at the micro switch and when I operated it there was no click. Hmmm, so I pushed the switch firmly and a loud click occurred followed by a click every time I operated it.

At this point I was fairly certain that this was the problem all along and it turns out it likely was.

So trans problem solved, but other issues still to be addressed.

Thanks for the help everyone, look for my new posts for more stuff to fix..

 

ive got a spare trans for sale if anyone wants it.

also, ive got a spare micro switch for sale if yours is busted.

 

Recently replaced my kickdown switch (mine was completely busted up... looked like someone had at it with a hammer!). Grainger's part number 6A885 is a direct drop in replacement. Only thing you have to do is kink the lever arm with a pair of pliers. It has a mark on it where you need to put the bend in. Same switch also for the WOT.

Switch, Snap Action - Enclosed Snap Action Switches - Switches - 6A885 : Grainger Industrial Supply

Got it last month and I distinctly remember it being less than $4, but the catalog link lists it as $8... strange...

Cheers,

Will