727 trans cooler fittings

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straightlinespeed

straightlinespeed

Sometimes I pretend to be normal
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Im getting rid of my bent, kinked trans cooler lines and switching it out to -6 PTFE Braided Stainless.

From what I've searched I need a 1/8" to -6AN fitting correct? I just want to make sure there are not different sizes. Thanks
 
All older torqueflite's take a 1/8" NPT fitting going into them. In the late 80's they switched to a larger fitting. I usually see guys run -6 line but it seems to me that -4 will do just as good. The i.d. of the fitting going in the trans. is 1/8" NPT so no matter how big the line is you put on it'll only flow what that 1/8" pipe fitting lets through. Dash 4 line I.D. is 7/32" which is way bigger than the adapter going into the trans. It would seem to me using -4 line and fittings would do the job just as good if not better since it's o.d. is smaller it might be easier to route and it's quite a bit cheaper.

Hopefully Del "67Dart" will jump in. He knows a lot about line and fittings. Maybe he can verify if what I'm saying is correct, or not
 
I sort of agree. However, the orifice does not tell the full story. Restricting a length of tube or hose based on a fitting restriction at one end means more friction in the line, so length does play a part. I think the real question is "how big" is the ID of the original 5/16 steel? I'd think that and no4 or maybe no5 line would be pretty close.

Hose is not all the same, either. In the "hydraulics" world I came from, we used a common single braid line for med pressure stuff everybody locally called "Aeroquip." I realize that's a brand and not a TYPE. That line, for no5, example, was .25 ID. But common 2 braid high pressure hose is "true dia" IE no4 hose is 1/4 ID
 
67Dart273 said:
I sort of agree. However, the orifice does not tell the full story. Restricting a length of tube or hose based on a fitting restriction at one end means more friction in the line, so length does play a part. I think the real question is "how big" is the ID of the original 5/16 steel? I'd think that and no4 or maybe no5 line would be pretty close.

Hose is not all the same, either. In the "hydraulics" world I came from, we used a common single braid line for med pressure stuff everybody locally called "Aeroquip." I realize that's a brand and not a TYPE. That line, for no5, example, was .25 ID. But common 2 braid high pressure hose is "true dia" IE no4 hose is 1/4 ID
Click to expand...

Thanks for clarifying things Del. I didn't realize different hose types were different I.D. Based my info out of Summit's listings and every -4 listing I saw said the i.d. was 7/32. I see your point about the length too. Funny how much in relation that is to voltage drop

Been a while since I checked the i.d. of 5/16 steel line but I think I measured it right at 1/4"
 
I was thinking about the restriction also where it goes into the trans, but figured I have a roll of -6 tubing just sitting here so I will use that instead of buying new line.

Can I say... Holy Hell are the AN fittings expensive!!

I understand what Del is saying about the restriction in length of tubing or pipe since I have to deal with that sort of thing at my job. Head pressures and such for runs of pipe for heating and cooling systems.
 
There have been a few discussions here about just exactly what threads are in the trans case. I don't recall if it was stripping the aluminum threads or cracking the case that brought it.
Since I've never used anything other than the OEM fittings, I don't know what thread type they have there. I can only suggest you research it before screwing in anything different.
 
Let me change the subject quick. Do you think I need a external trans cooler? If I plan on running the lines I dont want to have to rerun them later. Im running a 2800 stall converter.

I was told if you have a high stall converter they generate more heat, so a external cooler should be run. Not sure if this qualify's as that. Opinions?!?!?
 
A secondary cooler is sort of like a spare tire. Better to have and not need than to need and not have. We know the OEM radiators were designed to take care of OEM engine and trans. They knew when/where a secondary cooler was needed too ( like towing package ).
We don't really know squat about aftermarket radiators other than what they boast. Their performance claims rarely mention the trans cooler.
 
an external cooler is a MUST with a stall converter
 
I highly recommend it. As you were told a high stall unit (stock stall is 1400-1600 so yes yours is a high stall) creates more heat. Heat is a transmissions enemy.

Oh yeah, straight AN fittings aren't real expensive. It's when you get into bends that things get pretty expensive.
 
If you guys dont mind, I have one further question.

When I run the lines I run thru the radiator first, then the cooler correct? If that is the case is the front or rear fitting on the 727 the outlet?
 
straightlinespeed said:
If you guys dont mind, I have one further question.

When I run the lines I run thru the radiator first, then the cooler correct? If that is the case is the front or rear fitting on the 727 the outlet?
Click to expand...

Yup, cooler last. Don't remember, but if you bump the starter a bit, it does not take long to find out which line is which
 
The front one is out to the cooler and the rear is the return.
 
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