Rebuilt th350 intermittent "no go"

[cheeto]

Okay, this may get long winded, so bear with me, just want to cover all the bases.
 Recently purchased a '79 c10 350/350 turbo..recently rebuilt motor, ancient trans. Drove it for a while, trans would slip here and there and just felt worn out as can be expected. Reversed out of driveway one day, shifted into drive...nothing, like it was in neutral, nothing in 1 or 2 either...coasted to bottom of hill, rowed through the gears, got it to engage and drove it back to the house. Did the whole filter/gasket change...same results.
  At this point, I decided since I'm planning on slowly replacing/restoring the whole truck anyway, a trans was a good place to start. Purchased a rebuilt th350 from a local shop, installed it, filled it, etc..took it for a short drive, worked great...truck sat for about a week while i addressed some brake issues..took it out again and it did the EXACT same thing it was doing before...back out of driveway, reverse works fine, no forward gears until i coast it to the bottom of the hill and row through the gears. Once it engages, all forward gears work fine and i can drive it around, seems to do this 90% of the time.
 I haven't driven it very far, just a couple times around the block for fear of doing further damage, but am at a loss as to what is going on...seems odd that it's the exact same problem that was happening before the swap.
 I know the normal questions that will be asked, so a little more info:
 Everything i've read says stock th350, stock converter, holds 11ish qts....done
 TC was "primed" prior to installation
 TC was seated fully using the "3 clunks" method
 Appropriate gap between TC and flexplate upon install
 Fluid level drops from cold/not running to running warm, so pump is moving fluid (plus it goes in reverse and intermittently forward)
 It does leak a small amount out of driveshaft yoke ( i assume because of that silly hole GM engineered into some of them?)
 Seems to do this worse on initially backing out of driveway and trying to shift to a forward gear...my house is on a hill, so i'm on an  incline either way, does it facing both up and down the hill
 Have only driven it around the block, so not a whole lot of opportunity to see how it shifts
 I was leaning toward some sort of linkage issue, but i can feel it solidly "clunk" into each position, just not the "lurch" or engine load when it does this

So anyway, that's my conundrum, any input, suggestions etc.. would be greatly appreciated!!
Sorry for the ridiculously long post! 
 


 

[78BIG-TEN]

It could be a bad sprag,i had that on my th350 and found a cracked outer sprag race.

[BADAZ chevy guy]

Am I correct to understand that 2 different transmissions are acting the exact way? That sounds to me like a tork converter issue. Possibly the stator inside has come loose.

[cheeto]

Hey, thanks for the replies guys....guess I somehow forgot to mention in my rambling post that the TC was replaced with the rebuilt trans...
 As for the sprag, what are the chances of failure on 2 consecutive transmissions? I know it's relatively common on TH350s, but usually with shift kits, high power applications or under hard driving, none of which applies here and the rebuilt one hasn't been driven any farther than a couple jaunts around the block, not ruling it out completely, just seems relatively unlikely?

It seems to only do it on  initial takeoff when i shift from reverse to a forward gear, but from park it works okay (at least in the level driveway, i can move it back and forth fine)....as much as I hate too, perhaps I need to take the truck out for an extended spin, see if it fails under any other conditions, how it shifts, etc...just in the interest of collecting further data?

[timthescarrd]

If your drive-way is a pretty steep incline, it seems possible that fluid is running out of an area it should be while it sits, then it takes a minute or two to readjust.

Next time you back out of the drive, once you get onto level ground, shift to neutral and sit for a couple miuntes before shifting to drive

[cheeto]

The driveway is actually level, but the street immediately adjacent to it is a pretty decent incline, as soon as I back out, I'm facing either up or down hill, and this is where it seems to fail most often...as soon as I back out and go from R to D on the hill, nothing....coast to the bottom, shift from R or N to D, and still nothing, only once I put it back in P and then back into D can I get it going. (hope that makes sense lol)....
 The thought had crossed my mind that some sort of unwanted fluid transfer was occurring on the hill, not sure what would cause that and like i said, I'm thinking of taking it for a spin to see if this is the ONLY time it happens or there are other instances....also, once I get going it will drive back up the hill with no problems.
 The fluid level may be slightly low (put the 11 qts in as recommended by the rebuilder, plus a little due to the slight leak at the yoke) but surely not low enough even on an incline to cause zero engagement.

[hobbz]

how are you checking the level of your fluid? engine running and in park?

[cheeto]

Yes, engine running and in park, does register a little low...but at this point, i've put over 12 qts in it. Registers high when cold and not running, which leads me to believe that it is moving fluid and i haven't thrashed the pump due to incorrect TC installation.
 I got under it today, and noticed the shift linkage bushing is completely shot, to the point where there is excessive play in the rod and no tension on the spring, I'm gonna feel really stupid(but really relieved at the same time lol) if that's the problem, but could this excessive play somehow combined with that incline be the cause?
 Of course the auto parts store sold me a bushing that isn't even close to the right one, anyone happen to have a part number?