I have dropped the pan several times for filters but never did a complete fluid drain. What is the best way to do so?

 

drop one edge of the pan, let it drain, then drop it the rest of the way. put the pan back on with the gasket or whatever if there is one and fill it back up with atf+4

 

if you mean to get all the fluid out of the t-case and cooler lines you will do what srch said and then with the engine running put the trans in nuetral and let the trans pump the fluid out while you add more into it in order to keep it from running dry, however with fluid changes are proper intervals this is not necessary

 

i was told by an old timer to take a 5 gal bucket, fill it with the expected volume on new fluid. open a hose connection - run the suction side into the bucket and the other to a drain [lol - his words not mine] the run the engine watching the old fluid until you see clean fluid emerge. This sounds good in theory but I wonder how well it is in practice.....

 

the fluid is pumped in from the transmission pan, therefore i dont see how this idea would work out for obvious reasons that you dont have a suction hose available, unless you do it with the pan off (not a good idea)

 

Yeah, I'm with shrp that it just spells out catastrophy doing that with the pan off, just sounds to me like your transmission will run dry for seconds at a time. The way I do it is take off the cooler line and while it's draining out, run some new fresh transmission fluid down the dipstick tube. By far the easiest way IMO.

 

Do a pan drop and filter change, put a drain plug in. You can do a cooler line flush, just start it up put in nuetral for the pump for about 45 seconds, that will pump out a qt or so, just measure it. any add what ever came out. Just do the dump in pump and add a few times to get another 6 qts thru. Between the pan drop and this you will have changed most of the fluid.

I remove the return line from the cooler and slip a section of rubber hose over the fitting and pop it into a bucket to catch the fluid. Once done just reattach the line. Dont over fill.
Take for a spin to get fluid warm and check on stick with running in neutral. Fill to proper level.

 

If you don't have a drain plug in your tranny pan, here's a simple way to make the job less messy. Go get a pump like this:
http://http://www.harborfreight.com/...ump-66418.html
Then attach some clear vinyl tubing to the pump hose using an adapter hose barb fitting (Lowes/HD). I think I've used 5/16 or 3/8 tubing, something like that. You can snake the tubing down the dipstick/filler tube and then use the pump to slurp the ATF out of the sump. Works like a charm.