Turbo 400 "Shift Piston" Disconnected?

[OsmiumTetroxide]

Hey there, experts!
I'm putting a used TH400 into my 85 Bonus Cab (which is a crap shoot, I know). I took the valve body off, actuated the clutches with compressed air, etc. It seemed promising, so I threw it in the truck.

After getting everything hooked up, I fired up the machine and was disappointed when shifting between gears did absolutely nothing.

After mulling it over for a day at work, I thought I knew what was wrong. Sure enough, I had overlooked that the shifting ratchet pin actually is not seated in the shift piston. If that terminology I just made up is incorrect, I apologise.

Anyway, I've stared at this thing for an hour or so now and I can't for the life of me figure out how I'm supposed to connect this little pin into the seat in the piston.

It seems as if I could pull it out past the electronic kickdown solenoid, but I tried that and there doesn't seem to be a way to do that. Do I slide the ratchet's shaft out of the case somehow? If I move the ratchet from stop to stop, there's still no way to get the piston to attach.

I really appreciate your advice.

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[OsmiumTetroxide]

The only thing I've thought of is to just grit my teeth and pull the valve body off again, then line them up as I reinstall it. My other question, though, is that if I do that, will the check balls fall all over the place? Or do they have a little seat to sit in as the valve body loosens?

 

[Frankenchevy]

@Matt69olds or @HotRodPC would likely know.

 

[OsmiumTetroxide]

Update: I've successfully re-seated the pin. I loosened all the valve body bolts while still installed in the pan. I very gently loosened all of them equally, just barely enough to let the pin seat in the piston without enough of a gap to lose any checkballs. I then tightened everything up, put the pan on, cursed a lot, pulled the pan off, installed the filter, and then put the pan back on. I haven't filled it up and tested it yet, I'll get on it tomorrow.

Sorry for cluttering up the forum, haha

 

[Matt69olds]

Next time, loosen the 9/16 nut that holds the rooster comb to the shift shaft. That usually gives you enough wiggle room to line the manual valve up with the rooster comb pin.

If you ever need to remove the shaft for seal replacement without the fancy tool, to the above steps. Then bend and remove the nail (yes, it’s a actual nail!! GM spared no expense building these transmissions!!). Then you can remove the shaft. Denier the shaft, carefully pry out the old seal. Tap the new seal in placee with a socket. Lube the shaft, slide it in, reinstall the nail. Bend the nail so it can’t fall out.

 

[HotRodPC]

Yep, bending the nail would have been my method too. The nail only comes out without being bent when the pump is off. And yes, it is a finish nail without a doubt. I think GM did that to be funny.

 

[Matt69olds]

They also used nails for the governor weight pivots. GM spared no effort in looking for ways to save money.