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Auto trans AN adapter fitting leaking

Wookalar

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Nov 27, 2013
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458
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Arizona USSA
Hey all, I am having some trouble with some AN adapter fittings for auto transmission lines leaking. How on earth do I get these little @!*#!s to seal?

I am thinking that the brass fitting I am screwing the AN adapter into threads have been stretched beyond spec. Maybe I just need new brass master fitting. I am thinking that they install the lines at the factory with pneumatic tools because they were in so darn tight.

OR, the angles on the flared part are not the same on the brass fitting as they are on the AN adapter fitting which is causing fluid to get by. See the photo for reference.

I have tried the permatex sealant and it worked on one but the other is still leaking quite a bit, and I know people say to not use Teflon tape so what does that leave me with?



Thanks
 

EMX5636

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There are 2 main flares, JIC (AN for car guys) and SAE. If they are different, that would cause a leak. Also, the brass ones are prone to over tightening, and flaring the threads as you mentioned. You can use teflon tape or paste on the threads of NPT (pipe thread) but not on a flare fitting, as the threads don't seal anything, the taper does. I would try a new brass fitting, and just be a little more careful (read gingerly) tightening it. Could be that simple depending on where it's leaking from. Also, I've had the cheaper aluminum AN fittings split the flare if over tightened, so that's possible as well.
 

Wookalar

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Nov 27, 2013
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Arizona USSA
Much appreciated info, thank you. Here is the adapter fitting I'm using. Hard to tell if the angle is the same. I believe this is an inverted flare, AN on the left, oem piece on the right. Yes I cut that sob off.

The AN flare looks more steep, or maybe it's my imagination. /ubbthreads/images/graemlins/dunno.gif


 

Spyke169

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Aug 17, 2005
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324
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Greenfield, Wi
JIC comes in both 45 degrees and 37 degrees flare. -AN is basically 37 degree JIC, but tighter machining tolerance. As long as the JIC you are using is 37 degrees you can use it with -AN no problem. If I was you I would take the fitting into a hydraulic shop, If what you are working with isn't correct they will be able to tell you right away, and get you the correct fittings. Or you could try putting a little bit of grease on the flare surface, gently thread it together and apart, if the pitch is different you should get a distinct line in the grease.
 

EMX5636

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JIC/AN is 37*, SAE flare is 45* (along with different threads on some sizes) but Spyke is correct AN has tighter thread tolerances. For anything automotive , JIC/AN spec are interchangeable (not the degree of flare), aerospace and NASA etc needs to use the precision AN rated ones. I think inverted flare (I.E. brake and fuel lines etc) are 45* but I could be wrong. I know they make adapters to eliminate the factory fittings that thread into the case, so that would be my suggestion. Eliminate all your adapters etc.

After a quick Google search, looks like you need 12mmx1.25 (one that allow an o-ring or crush washer) to -6 AN. Looks like most online shops (I use JNZ Tuning) have these available.
 
Last edited:

Wookalar

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Nov 27, 2013
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Arizona USSA
Thank you both for the info and suggestions, I was unaware of what JIC referred to but had read earlier today about the two different angles.

I will bring these two fittings to a local shop and see what they have to say. The main fittings I would like to keep since they are a major pita to remove with the trans in the car. I just need a male fitting with matching angle that adapts to a -6 male flare and I'm in business.

Thanks again.
 

iceman69510

Turn Right Racing
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In general, good responses, but I disagree with the quoted part of this statement. Sealing of flared fittings relies on complete circumferential point contact between fitting halves. For any fluid I would not recommend mixing these (semms small, 8 degrees, but it is significant). Mixing is most likely the reason for his issue in the original post. I would certainly never mix for brake or other pressure lines.

Quoting EMX5636:
JIC/AN is 37*, SAE flare is 45*. For anything automotive, they are interchangeable,

 

EMX5636

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Sorry Iceman, I should have worded that differently. I'll edit, but I meant that JIC and AN spec are interchangeable in our automotive applications, not 37 and 45 degree.
 

Wookalar

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Nov 27, 2013
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Arizona USSA
No. It's a A340E 4 speed auto on a Lexus.
 

prove_it

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Jul 3, 2008
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Sioux Falls, SD
Have you cleaned it off and ran it and watched to see the leak form? Just curious if you've pinpointed the real leak.
 

Wookalar

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Nov 27, 2013
Messages
458
Location
Arizona USSA
Yeah, I was under it when someone started it. Actually I think it came loose on me when I installed the hose end fitting to the adapter, so I just used some med Loctite on it today and I will check it in the am.

I spoke to a guy at a local store today and he said the angle is the same on the adapter side as the stock fitting, 45*, and that the AN hose end is the 37*. /ubbthreads/images/graemlins/dunno.gif

Update. The Loctite worked well, no leaks. Basically I just cleaned the threads with parts cleaner and used a bit of med Loctite on the adapter fitting into the brass fitting and let it dry for a few hours. Then I went back and put the hose ends onto the adapter fitting carefully using two wrenches so as not to break free the Loctite seal or overtightening (with a small amount of anti seize to prevent galling/binding damaging the aluminum threads). No leaks today after a test drive.
 
Last edited:
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