Is there diagram of how to air check a assembled trans with the valve body off? The flow charts I'm finding are for the valve body it's self, not below the separator plate. Or is there a better way? Thanks

If you assemble the transmission in the order shown in a ATSG manual:

-You can air-check the Low-Reverse clutch pack with the valve-body off
-You can air-check the separate chambers of the 2-4 Servo assembly with the valve-body off.

As far as air-checking the other clutch packs go, you would place your pump assembly down so that you could install the assembled reverse-input drum and assembled input drum all together... Air-checking these 4 clutch packs via the passages on the back-side of the pump assembly.

Note: if you build a good amount of these regularly... the pump assembly and valve-body can be modified into air-check tools to test the transmissions before final assembly.

This is something that I used to do when I was starting out with my business...
After you have done enough of these, you will develop a feel for most everything and not have to bother with making air-checking tools.
I also use a transmission run-stand these days.

Last one I did I had an issue at first getting the forward and 3/4 to air check. Not sure what happend? After working it quite a bit, disassembling, then reassembling it it finally started to air check. FWIW, I used scarf cut sealing rings on the input shaft?

I've used these "step cut" input seals on 700s. Dana includes them in his kits. Petty good if you dont have access to the resizing tools. I also used the blue scarf cut seals on the stator. Not sure about scarf cut on the 4l60e?

I've used these "step cut" input seals on 700s. Dana includes them in his kits. Petty good if you dont have access to the resizing tools. I also used the blue scarf cut seals on the stator. Not sure about scarf cut on the 4l60e?

Most people today use the "Steel/ Bonded Pistons", which makes things pretty much fool-proof.
It is easier for a beginner to have an issue with the lip-seals used on an early aluminum apply pistons.

As long as the Scarf-cut PTFE sealing rings were installed with the ring-ends correctly placed...
They usually air-check fine.

MAKE SURE that the small green O-Ring gets installed towards the bottom of the drum first or around the same time as the 3-4 clutch apply piston.
And make sure to lubricate it with assembly lube or ATF once it is installed.
This O-Ring is often forgotten by beginners.

I often crank up the line pressure on these units and prefer the solid-PTFE rings.

I didn't have any leaks on the low reverse piston or on the input drum assembly. The reverse drum is hard to air check and I should of air checked all three components as an assembly before installing them into the trans.
I used solid-PTFE O-rings and slid in pretty easily ( I alittle problem with resizing the pump O-rings for the rev-drum but got the slide in. I'm sure every thing will work, BUT I think of to many what ifs.

Has anyone ever made a wet pressure test tool to run fluid into pump at line pressure ? Also, is there a way to put a gauge on afl pressure?

This is an old thread and you may get more if you start your own.
I use an air test plate that I cut and drilled myself out of a piece of 1/2" of aluminum plate. I can test FWD, OR, 3-4, Rev, L/R, P/R, 2nd, 3rd & 4th circuits. I do need 2 sources of 40 psi to test the 2rd release..