Rebuilt 727 input gear won't turn

RVDodge

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Jul 18, 2023
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Make
Winnebago
Model
Elandan 2
Year
1978
Miles
?
Engine
Mopar 440
I finally finished rebuilding a 1978 727 transmission that sat behind a Mopar 440 engine.

Everything was going well, I checked clearances on all clutch packs, made sure the final end play was within specs. I put much Petroleum jelly on most surfaces.

So I assembled all the moving parts of the transmission, the input shaft, clutch drums, installed the pump, the drum bands. After all this I was still able to turn the input shaft with locking pliers.

Then I installed the valve body and the fluid pan, I got busy with work so the transmission sat for a week or two.

Now, that I'm about to completely finish the transmission I can no longer turn the input shaft!! Is this normal?
 

billr

wrench
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How much torque are you applying to the shaft?
 

billr

wrench
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You need to measure, or make a decent guess. I would expect some drag from all the trans innards. Maybe 15 lb-ft or less?

How about the tail-shaft, can you turn that at all? Not in "park", of course.
 

RVDodge

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Yes, I can turn the output shaft once I moved the shift knob out of park.

I do remember having to stack two input shaft spacers to reduce endplay....the final end play was 0.0025.
 

billr

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Take the pan and VB off, see if that frees up the input shaft. The convertor is not on yet, correct?

I really would like to get some clue: is the shaft locked solid, or just takes a lot of torque to turn?
 

RVDodge

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No, the converter is not on yet, I'll take off the pan and valve body, see what happens.
 

paulo57509

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Is the VB secured to the case with different length bolts? You might have a long bolt in the wrong position.
 

bp042665

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just saw this and it should've been in transmission forum but i would check bolt placement on valve body and there should be some drag as like bill said you could've stacked it not seated down all the way and have input drum pinched AKA forward drum
 

RVDodge

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I removed the valve body and all the bolts were the same length. The input shaft still wouldn't turn, so I found out it was the spacers behind the pump and between the clutches that was causing the problem, I put in thinner spacers and it solved the problem.
 
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