My cooler lines are spent so I'm upgrading them to braided steel lines I had on the shelf from a previous project. I couldn't get any info on what they are so I assumed they were similar to th350 and Th400. But they are slightly different. The kit uses AN/JIC fittings with 37 deg conical seat and comes with various conversion fittings for th350 Th400 700r4 and 4l80e. In the pix you can see the two darker fittings where the larger fitting with crush washer goes into trans. Then a smaller inverted flare threads into the larger fitting. My kit will not thread into the larger fitting. (ie there are no replacement fittings for the inverted flare unit.). However they will thread into the trans directly (ie replace the larger fitting). My question is; 1) if I use the larger fitting do I need to add a crush washer? I'm not sure if it I can just add one, or if I can just omit it. 2) otherwise would anyone know what the size and thread of the inverse flare is? I'm going to see if I can find some JIC to inverse flare adapters. Failing that I need to do option 1 but not sure about the crush washer. Any help appreciated.
I would go with option 1, but I also am unsure about the crush washer. Seems like your kit would include a washer if needed though.
When I replaced my cooler lines with Push-Lok hose, I used -6AN fittings. All I had to do was get adapter fittings at the radiator and the transmission. The ones that go into the transmission are a special thread. They are not pipe thread, they are NPSM, These are the size I used, https://www.summitracing.com/parts/...brrizTiJ4Fx8qcsh6JlBQnCZa3QsCdGct0DFaD6NiUDW8 On the radiator side, it is 1/2-20 inverted flare to -6AN, https://www.summitracing.com/parts/...YTTMgBf20hJ3mpQ1qTof4-Hbp4YXhZ2jK7VFzH8U7VhdI
After a bit more research it seems alot of people are replacing the crush washer fitting with an O-Ring style and I've not read about any ORing related issues. But I think the seal is necessary either way. To switch to an ORing style a suitable fitting is needed, and has a relief at the base of the thread to house the ORing. You cannot just add an ORing to a regular fitting or the existing crush washer style fitting. The ORing style fitting is alot more common it seems to get. If I replace the big fitting I will need the crush washer or ORing, otherwise I can add a smaller fitting into the original large fitting.
Just to close off this thread, I can confirm that the trans case thread is indeed 1/4 npsm as shown in Larry's link. In other words, the th350/Th400 fittings will work. And a washer or o ring is required. If you search for transmission cooler fittings, these are the ones that typically come up. The smaller fitting is a different inverted flare thread that I could not find a fitting locally so I am just replacing the larger fitting and bypassing the inverted flare all together. If you are making new inverted flare lines you could reuse the old fitting, or get a different sized reducer to accommodate whichever flare fittings are available to you.
A kit was recommended to me from Evil Energy: Part number for the kit is KT01269AN6BK-HW Use these fittings: Part number for the TH400/350 fittings is ICT 551114 Available from Amazon, etc
