4L70E Cooler Line Size
 

I’ve tried to search for info on the forum but not much out there. Looking to see what others have done in the way of automatic transmission cooler lines. -6 AN fittings are plentiful but is that large enough? Also, with ease of installation aside, I’m debating whether I should use flexible lines or bend some hard lines…and if flexible, do they need to be PTFE or just standard fuel line? This is my first automatic in a hot rod so I’m looking for some guidance. For reference, the car’s a 67 Nova and while it’s built up for autocross, that won’t be its primary purpose. Thanks for the help!

My 68 Camaro utilizes a 4L80E.
I like hardline stainless.
I ran 5/16” diameter Swagelok 316 alloy SS.
5/16” may sound small but I got that direction from Gordon Stoney who was supervising engineer for Hydromatic Division at GM.

I autocross (not very good at it) and “spirited driving” on the street.
Mark Bowler sold me the transmission case fittings from Sonnix and he knew I was running 5/16” lines with no worries.

CONCERN: make sure you get the proper trans case fittings because, at least for my 4L80E, the rear fitting has a nozzle that lubricates rear spider gears. No nozzle = burnt gears! I learned this from Mark Bowler.

If you go flex, please get PTFE.

Thanks and best of luck

That’s some good info, especially about the fittings, never would’ve considered that…thank you for the feedback!

572 Camaro,
On my 4L80E I ran 3/8 line did you have a discuss with Gordon of the effects of 5/16 vs 3/8 line just inquiring if there were any particular reason of the 5/16 line. Would be hard for me to change now anyway.
Thanks
BB

BB,
Don’t change a thing!
3/8” diameter will work fine.
I didn’t ask Gordon about larger diameter.., my bad.
I chose 5/16” because:
1. Mark and Gordon both indicated it was big enough.
2. I got really tight clearance everywhere and I can get tighter bends in my tubing.
3. Frankly, it looks better..,


BRAG: we won most outstanding engine bay at Detroit Autorama a couple years back.

ADVICE: if you run “hard” engine mounts, and if you run hard lines, no need for a flex hose in between.

BOTTOM LINE: You are fine.., just shut the hood and drive it like you stole it!

I used 3/8” nicopp hard lines with -6an fittings for TR6060. I also connected both hardline ends with a short flex line for ease of serviceability down the road. I’m pretty sure you can’t use the same flex line for fuel and oil. I went with Mr. Gasket push on style flex line. Their fittings are very affordable, no tools needed to install and don’t leak. Here’s a link to Holleys site, you can pick from the drop down menu fluid type and assembly method. It’s very useful.

https://www.holley.com/products/plum...ings_and_hose/

Excellent, thank you!

My stainless lines were a little bit of a chore too. This is from when I got the project started last year. I then ran the tubing from the starter tucking next to the pan as GM did forward up near the radiator. I used PTFE braided lines for the connections. I'm thinking with the trans cooler having -6 AN I should be good :thumbsup:
BB