At my wits end with these damn torque converters
- Thread starter ULTM8Z
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ULTM8Z
Veteran Member
GV = Gear Vendors
Its the bolt on overdrive unit.
Thanks ChevyReb. Yeah this is the 4th time I'm dropping the transmission in two years. Suffice it to say I plan to get this resolved before I put it back up this time
Its the bolt on overdrive unit.
Thanks ChevyReb. Yeah this is the 4th time I'm dropping the transmission in two years. Suffice it to say I plan to get this resolved before I put it back up this time
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ULTM8Z
Veteran Member
Interesting... would like to get you transmission experts' take on this...
https://transmissioncenter.net/shop/torque-converter-installation-instructions/
Coincidentally, I caught up with a drag-racing friend of mine in the hall way at work today and was telling him about what's going on with my transmission woes... he's built several TH400's in his time, so fairly familiar with automatic transmissions..
He said even though I may have seemingly solved the out of balance on this latest converter by rotating it against the flex plate last year, there may have been sufficient vibration remaining (that I couldn't feel in the car or distinguish from "background" vibrations inherent in a muscle car like this)... to slowly wear out the pump bushing and eventually cause the more prominent vibration that manifested itself just before the catastrophic failure.
Which is interesting in light of this paragraph from PTC's website. I definitely have not been doing that step as part of my installation process, as I have never seen that in either the Hughes or the TCI instruction sheets...or anywhere else for that matter... and obviously I'm no expert on transmissions to think of that on my own.
Hmmmm...
But... thinking back of the history of this saga...
That LT1 Vette converter was in the car for ~20 years before it failed. Who knows how much crap has collected in the crankshaft over that many years. The Vette converter went into essentially a brand new ZZ4, so it was probably spotless, and thus I had silky smooth operation.
So my thinking is, I then after the Vette converter failed, I installed Hughes and TCI converters at which point they both fell victim to what PTC is describing. The TCI wasn't as bad as the Hughes, so maybe the act of R&R-ing the Hughes removed some of the junk in there. Then R&R-ing the TCI improved it a little more, such that my latest converter out-of-balance was able to "papered-over" by rotating it against the flex plate.
This seems like the most plausible explanation at this point to me, no?
https://transmissioncenter.net/shop/torque-converter-installation-instructions/
Coincidentally, I caught up with a drag-racing friend of mine in the hall way at work today and was telling him about what's going on with my transmission woes... he's built several TH400's in his time, so fairly familiar with automatic transmissions..
He said even though I may have seemingly solved the out of balance on this latest converter by rotating it against the flex plate last year, there may have been sufficient vibration remaining (that I couldn't feel in the car or distinguish from "background" vibrations inherent in a muscle car like this)... to slowly wear out the pump bushing and eventually cause the more prominent vibration that manifested itself just before the catastrophic failure.
Which is interesting in light of this paragraph from PTC's website. I definitely have not been doing that step as part of my installation process, as I have never seen that in either the Hughes or the TCI instruction sheets...or anywhere else for that matter... and obviously I'm no expert on transmissions to think of that on my own.
Hmmmm...
But... thinking back of the history of this saga...
That LT1 Vette converter was in the car for ~20 years before it failed. Who knows how much crap has collected in the crankshaft over that many years. The Vette converter went into essentially a brand new ZZ4, so it was probably spotless, and thus I had silky smooth operation.
So my thinking is, I then after the Vette converter failed, I installed Hughes and TCI converters at which point they both fell victim to what PTC is describing. The TCI wasn't as bad as the Hughes, so maybe the act of R&R-ing the Hughes removed some of the junk in there. Then R&R-ing the TCI improved it a little more, such that my latest converter out-of-balance was able to "papered-over" by rotating it against the flex plate.
This seems like the most plausible explanation at this point to me, no?
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sandlapper
Veteran Member
kinda sorta like installing main bearing shell in a block w/ dirty-rusty saddle and/or crap on back of shell; don't.
ULTM8Z
Veteran Member
If that's really the problem, I may try the Hughes again.... other than the vibration, it was a really good performer. I liked it a lot.
Put more power to the ground than the TCI and noticeably more than the no-name brand I have now.
Put more power to the ground than the TCI and noticeably more than the no-name brand I have now.
ULTM8Z
Veteran Member
Had a little time today so drained the oil and transmission fluid today.
Both looked really good. The transmission fluid actually looked like it just came out new from the carton it was so clean.
I dragged a rare earth magnet across and around the bottom of the drained fluids as well and not one spec of metal came out.
So that's at least some good news...
Both looked really good. The transmission fluid actually looked like it just came out new from the carton it was so clean.
I dragged a rare earth magnet across and around the bottom of the drained fluids as well and not one spec of metal came out.
So that's at least some good news...
Have you checked end play on the crankshaft to see if the thrust bearing is within spec ???
ULTM8Z
Veteran Member
Chuck, not yet. When I get the transmission down ill be able to make a precise measurement with my dial indicator.
Maybe in another week or two I'll have enough time to pull it.
Sometimes other stuff in life going on takes priority...
Maybe in another week or two I'll have enough time to pull it.
Sometimes other stuff in life going on takes priority...
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