TH350 Trans cooler thread size on case
October 22nd, 2021, 06:00 AM
#1
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Join Date: Aug 2012
Location: Brunswick ohio
Posts: 23
TH350 Trans cooler thread size on case
Hello All,
Just had a TH350 rebuilt, rebuilder saying there was no cooler fittings installed, eventhough there was fittings there with the 5/16 inverted flare ends. From what Ive found the casting ports should be 1/4-18NPSM. I have 1/4-18NPSM to -6 and they will only screw in approx. 3 threads. Trans shop is saying it requires 1/4 NPT thread. I don't want to crack the case and they are unwilling to install them either. Trans is going into a 71 Cutlass Supreme, trans came out of a mid 70's firebird. I'm hoping they just buggered up the threads, but before I run run a tap into them to try an clean them up, wanted to check first.
Thanks in advance for any help or advise on this
Brian
Just had a TH350 rebuilt, rebuilder saying there was no cooler fittings installed, eventhough there was fittings there with the 5/16 inverted flare ends. From what Ive found the casting ports should be 1/4-18NPSM. I have 1/4-18NPSM to -6 and they will only screw in approx. 3 threads. Trans shop is saying it requires 1/4 NPT thread. I don't want to crack the case and they are unwilling to install them either. Trans is going into a 71 Cutlass Supreme, trans came out of a mid 70's firebird. I'm hoping they just buggered up the threads, but before I run run a tap into them to try an clean them up, wanted to check first.
Thanks in advance for any help or advise on this
Brian
October 22nd, 2021, 04:11 PM
#2
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Join Date: Jan 2010
Location: central Indiana
Posts: 5,261
I don’t know the actual thread size, but they aren’t tapered pipe thread. They use a sealing washer between the fitting and the case.
Even though it’s not right, countless people thread tapered pipe threads into the case. As long as you don’t get crazy with tightening them, you could go that route.
It should be pretty easy to find the correct fittings.
Even though it’s not right, countless people thread tapered pipe threads into the case. As long as you don’t get crazy with tightening them, you could go that route.
It should be pretty easy to find the correct fittings.
October 22nd, 2021, 05:06 PM
#3
Full-time Taxpayer
Join Date: May 2010
Location: Texas
Posts: 387
Last edited by Qwik71442; October 22nd, 2021 at 05:09 PM.
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