I am trying to hook up original style transmission lines from my 74 C4 to my radiator cooler. Issue I'm running into is the cooler ports on the transmission appear to be 1/2 straight cut (maybe 1/2 - 20) female threads and the lines are 1/2 double flare male threads. I assume there is a fitting or adapter that goes between just like the radiator has but I can not find anything. I have searched Mustang and Bronco parts suppliers with no luck, NAPA just laughed at me, all I can find are fittings to 1/2 to AN6 adapters. Any ideas or solutions?
I think the case is threaded for 1/4 pipe STRAIGHT thread. You can get fittings that screw in and have an o-ring and jam nut. It is POSSIBLE to use 1/4 NPT but not a great idea.
I originally purchased one of those but the threads are way too small, maybe they're for an earlier C4? That's pretty much what I need but 1/2 inch to 1/2 inch.
1) Tranny shop. 2) Real hardware store. Suggest both with the old guy who wears his glasses down his nose and calls you "Sonny".
Heed the advice of CHoffman! If you tap the holes to 1/4" pipe, (even with Teflon paste/tape) you are flirting with putting a crack in the case! Many 'street rodders' brought cars in with 350 TH trannys, with 1/4" pipe fittings for a remote cooler. Weld the case? No thanks... I'd replace the case, and clutches and o'haul kit as needed.
Tom's Bronco Parts just called me back and say they found what I need and are mailing them out to me on Tuesday. Hopefully they understand what I need and the part I need shows up. Was the fitting at Ace 1/2 inch straight pipe thread to 1/2 double flare?
1/4" straight pipe thread measures about .025" larger than 1/2" bolt thread. I don't think you have anything that is 1/2". Your flare should be for 5/16 tubing and the threads on the flare fitting measure about .010 smaller than 1/2" bolt.
What you need is this. The question is, are the threads in the transmission NPT or straight pipe. If straight, you need a gasket as the threads won't seal tightly. The fitting will also have to be straight pipe. 1/4 male pipe to 5/16 inverted flare. Both will measyre about 1/2"
The hose barb that I checked to see if it would thread into the transmission will start to thead into a 1/2 - 20 nut just like it does into the transmission. That is we're I'm getting 1/2 from, so you're probably correct.
Fittings and bolts are a great source of confusion and frustration. There are hundreds of combinations that will "ALMOST" work, and in fact can be forced together. Unfortunately, they will always leak. And don't even think of adding metric crap to the equation.
That being said I did try this fitting and it was way to small for the transmission but fit the line.
That's what I'm hoping... Unfortunately CJ Pony Parts doesn't list the thread sizes so I can't check.
Finally have a quick update. Tom's Bronco Parts sent me the incorrect part (it was just like CJ Pony's part) looks like it was 1/8 pipe thread. After searching some local hardware stores I finally found a 1/4 npt by 5/16 inverted flair fitting like pictured above and it seems to work. I am sure it is not straight thread but the transmission had barb fittings installed before to a remote transmission cooler and I am sure those where not straight thread either so I am going to give them a shot. I started it up and went through the gears and no initial leaks but my carb is acting up and running way rich so I couldn't test it for as long as I would have liked to. Thank you Choffman41 for helping me sort out the difference in threads and sizes. I would have never figured this out without your help!
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