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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: JohnnyPopper on July 12, 2019, 12:58:46 PM
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Hey Guys,
I bought a '88 C-30 and am replacing the th400. Got a used one (warrantied) from a yard I do a lot of business with, the tech pointed out that the T/C has 6 bolts.
Never seen one before, the original has 3.
Does anyone know the significance of why there are 6?
It came out of a '89 step van.
We opened up the pan and it was clean as a whistle.
Thanks for any guidance you can offer!
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i've been seeing a few of these lately, because i have to do research on my own torque converter issues.....
i think 6-lugs are more heavier dutier/diesels.
What engine is in your c-30?
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3 are SAE threads, 3 are Metric. Choose which set of 3 you need
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Wow, that's all the difference? You mean my new T/C isn't special after all? :'(
When wrenching to get this pig out, I ran into bolts Sets, i.e. rear mount bolts, that were clearly metric, the rest being SAE.
The T/C bolts were/are 15mm.
The only thing I could figure was that the BIG 3 were so $ conscious of cost per vehicle that they went with lower cost hardware where ever they could.
Please feel free to disabuse me if there is another reason!
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Carl (Zeig) all the threads are the same. Now what?
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Choose the 3 that line up with your flex plate
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i know on my motor swap the flex plate on the motor there was only 3 holes for the th400. someone modified it to fit the 700r4 (made the holes closer to the edge). when i mounted it up to the 4l80e i had to bring the holes back in
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There are 6 points on the flexplate. Used all 6.
So there is no indication that this is a heavier duty T/C?
Came out of a delivery van.
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There are 6 points on the flexplate. Used all 6.
So there is no indication that this is a heavier duty T/C?
Came out of a delivery van.
OK. I learned something today. I have 2 TH400's and the flexplate in my 85 has 6 holes. I will have to check and see if mine is the same way. I am missing a speedometer drive gear before I put the new transmission back in...
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i didnt know about the differences till after i bolted the cummins in place and no bolt holes lined up. PIA to pull it back out and modify the flexplate to work with the 4l80e
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There are 6 points on the flexplate. Used all 6.
So there is no indication that this is a heavier duty T/C?
Came out of a delivery van.
Yes, based on my research it is heavier duty and/or installed behind diesels. C-40,50 trucks, motorhomes etc.
2) if you look at the custom aftermarket converters that are put behind engines making 800+HP, they are 6 lugs.
That's all i know for now.
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Wow Stuart, quite impressed! Thanks!
I admit I know very little about T/C's but wonder if this has a different 'stall' RPM?
I know that it can vary by design and application.
Hopefully this one isn't with a high RPM, however it is a C-30 with H/D rears suspension.
Any other Heavy Weight care to add to our knowledge base? TIA!