Looking for a fitting


What size are the threads for the tranny cooler in the radiator. My car came with -6 braided stainless tranny lines installed, but whoever did the conversion used all kinds of crazy fittings to connect the lines to the radiator & some of the fittings have a reduced ID & I'm sure that they restrict the fluid flow. I'm trying to figure out what size fittings I need to go from the tranny cooler in the radiator to a -6an line? I thought it was 5/16" to -6, but those didn't fit.
In the radiator itself they are 1/8" NPT in the front of it.

Pipes that come out of it are 5/16" inverted flare pipe.

Factory has adaptors that fit into the radiator, with the custom bent short 5/16" pipes that go into those wrapping them around to the battery area location where they are coupled with coupler fittings to the factory long 5/16" lines that go to the tranny.
Just stumbled across this post as I was searching for posts related to 86/87 radiators and the transmission line fittings!

Nearly 2 years after pulling my engine for a rebuild - I've finally got the engine back in place.

I ordered a replacement "3-core" radiator from Arizona GN (Nick). They do these on an "exchange" basis - where you just send them your tanks (they don't need your core).

Well - went ahead and got ready to install the new radiator and low and behold - the transmission line fittings (90 degree brass elbows) are too small for the line fittings in the radiator. It appears that the elbows/fittings also serve as a reducer - as the fittings on the lines themselves (without the elbow) fit the holes in the tank fine.

Am I correct in reading that there should be reducers/adapters in the fittings on the tank?
The factory radiator has 1/8" female NPT threads in it and a right angle adaptor that is 1/8" male threads to female 5/16" inverted flare pipe.

The short factory bent lines go into that fitting and wrap around the radiator inside the rubber isolation mount and join at the couplers that join them to the 5/16" flared pipe lines that go to the tranny itself.

I don't think you can bend those lines to go directly into the radiator should it be the wrong end tanks sent to you by mistake.

I'd ask Nick via email or PM or phone about that particular recore.

I always thought since you send in factory end tanks you would get the recore done with the correct factory threading in it which would make the factory adaptors go in just fine.

There were aftermarket radiators listed to fit TR's in the 90's that had the wrong tranny cooler fittings in them. :mad:

Well...you can imagine my surprise then the "right angle adapters" wouldn't thread into the tank fittings. I compared the pictures (gotta love digital cameras) I took during disassembly - and it appeared that the fittings threaded directly into the tank fittings (I couldn't see any sleeves or adapters).

Yes - I realize the lines can't be mounted directly to the radiator tanks without elbows - I was just using them to compare thread size/type.

I have no clue how these could be the wrong tanks - as they have both the oil cooler and trans cooler fittings.

My only thought was that the original tank had some type of insert/sleeve in the tank fittings that I failed to notice and whoever returned the tanks (cores) that ended up on my radiator removed them.

Otherwise - the tanks would have to be from a different (but similar) application (?).

I've called Nick and sent two email messages (which he hasn't responded to).

I'll have to give him another call I guess.

And the wife wonders why it takes so long to put a car back together...KM
Here is what may be the problem.

I found my old aftermarket radiator out in the back yard and it still had the fittings I made to make it work in it.

The holes look a lot like a stocker but just slightly larger than the NPT holes so someone may have sent one back as a stocker and you ended up with it, what luck. :frown:

The picture shows the fitting I made under the 5/16" flared inlet that this wrong radiator had, basically it's a piece of the 5/16" threads soldered into a right angle NPT adapter machined to fit. Below that fitting is an NPT stock type adapter and note the thread differences.

I doubt you will have much luck with a vendor correcting the problem after a couple of years but you never know.


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Thanks for the follow-up and for the picture.

While the engine's been out for nearly 2 years - I ordered the Radiator in July.

Hadn't thought about "aftermarket" replacment radiators - although I certainly have heard of them and others who've had problems. Never occurred to me that someone may have sent one in as a core.

Again - thanks for taking the time to respond.

I guess I have to keep chasing Nick.