OEM-type metal lines from trans up to maybe 14-18" from trans cooler mounted on radiator
Ends of metal lines flared/barbed
Trans cooler fluid line hookups are NPT fittings w/ barbed ends
Rubber line supplied w/ trans cooler (Is this considered "high pressure"?)
Lines attached on both ends w/ screw-type hose clamps

NHRA rule book says the trans lines must be metal or "high pressure" type; doesn't specify attachment mechanism

It was never questioned in the past, but I wanted to ask anyway. Oh, mid-10 sec car, FWIW. Thx

If you want yo can change over to braided at the ends of the steel lines then that will give you some
flex and vibration resistance ... use compression fittings on the steel

I’ve seen enough carnage from leaking oil/fluid getting on the tires.

I don’t care what anyone says, manufacturer or not, I would never use any rubber in cooler lines.

Spend some time bending a nice set of lines and use flare fittings and never worry. Just put a wrench on each fitting once in a while to make sure they are tight.

Would it pass tech around here? Yessir, no problem.

If it were me, I'd run it from trans to cooler completely in -6 AN braided line. I did that to my car years ago and it made things much easier. Not having to deal with the hard lines around headers, starter, crossmember, shifter linkage, etc.

The OP setup would pass tech - use hose for ATF.
Just check the hoses before a race, and route them so they're unlikely to dump fluid anywhere near a tire.
I prefer as much hard line for fluids as possible, for a few reasons.
Hoses help dampen vibrations, and much of the time make servicing easier.

I have my cooler mounted under the floorboard and that is exactly how it has been plumbed since 1995. I have replaced the rubber hoses a couple times as preventative maintenace, but to tell you the truth I have been to a lot of tracks and no tech guy has ever even looked at my trans cooler.

No more than six inches of rubber hose in total - I thought was the general tech rule - if it were mine I would use braded instead of that may-pop hose they supply in the kits

No one has ever checked my car. The only things I have been checked for is belts and helmet.
My cooler is mounted under the trunk and I ran -6 PTFE hose. Was not expensive when I did it a few years ago. $50-60 maybe?

Nobody has ever said anything about trans lines that I know of in tech.

Back in the day when I ran 11s and 12s I ran some steel line rubber hose double clamped sketchy stuff but eventually I switched to all braided.

I have to laugh at a few on here.. they all talk safety but to do a job right they will blow it off... or they
say.. next time.. even if they have never been checked on it

Agree. Bad enough to oil the track and pi$$ off their fellow competitors. Worst case they crash their car or it goes up in flames.

Our mopar race has been called the “oil dry nationals” for years by some of the Chevy and ford guys. Most of it is deserved. I still get a kick out of selling old school Hemi guys running flex hoses on their radiators.

Sure, rubber fuel line and worm clamps on non flared, cut off tubing is a bad plan...but modern high pressure push lock flexible hose is no joke. I've been using it on an efi system in street car heat since 2009 to connect the hardline to the fuel rails for example.

That's the direction I've decided to go. Need to see what fittings I have on hand, plus don't believe there's enough -6 line left to do the job.

Not I. I went with-20 AN upper and lower radiator hoses on my build. One of my buddies, crossed the centerline and slapped the opposite wall one time all because of a $1.19 radiator hose clamp let loose on his BBC race car.

Very nice.

If you rely on the tech guy at your local track for guidance on building your car, you are doing it wrong. Passing tech, even by the book tech, is a minimum requirement. There's always a better, safer way.


High pressure hose made for trans cooler applications is a minimum.


If you are using clamps like this...




instead of like this, you are asking for trouble.




Everything I've done for a long time now is AN type hoses and fittings including coolers with provisions for those style connections. I've seen too many messes from doing it the other way.

I used to tell Elmer his Mopar meet was his track's annual rust proofing treatment.

IMO whether it woudl pass or not is questionable. At Capitol and Masin Dixon probably never be an issue no matter what was used. Question is are you comfortable with this set up? IMO use better materials just for peace of mind. You can make steel line easy enough to go to the converter with many options. B nuts and sleeves to flexible braided line, bend the steel line to fit the cooler, simply use braided line end to end. But what ever you do use a trans cooler that has actually fittings or provisions for them. not one that has hose barbs on it......

I would highly recommend Teflon (Aeroquip TFE style) hose and fittings for that application. Trans fluid is nasty and the rubber/stainless braid stuff will degrade over time.

Steel tube can be flared and assembled with nut/sleeve type fasteners. We've done that with 5/16" line using -5 AN stuff. 3/8" goes to -6.