SAFE transmission line HOSE??

Is there such a thing as a safe/reliable transmission HOSE? I'm a little apprehensive about using high pressure fuel hose as a transmission line. I've installed a trans cooler and don't have access to the tools needed to do a double flare on hard lines.
High pressure hydraulic line appears to be to stiff/thick to use hose clamps!!?
All suggestions appreciated.


1986 Buick GX1

GX1 #001 [The One and Only]
I believe they sell transmission cooler line specific hose but if it's not to your liking or not available the SAE 100R3 hose may fit the bill.

SAE 100R3 is fabric braided medium pressure hydraulic hose that can be tightened with hose clamps. It's related at 1130 working pressure and 4520 burst pressure for the 3/8" size.

I say fabric braid to distinguish it form wire braid.

SAE 100R1 is single wire braid hydraulic hose and SAE 100R2 is dual wire braid hydraulic hose.
I have no idea why they labeled it with the R3.

I installed my trans cooler using the SAE100R3 hose in '87 and hasn't come apart yet.


Staff member
you should not need to do any double flare to install transmission cooler lines
just disconnect and remove one of the OE couplers by the battery , the oe lines are double flared
slide the line nut back and push hose on over the already flared end and then clamp it
you can get trans cooler specific hose from derale but a good tanscooler kit should include proper hose and clamps


Seen Your Member
I also used bendable hard line. I've seen good rubber hose fail after 10+ years and I knew my car would be around longer than that. A basic flaring tool is inexpensive (same tool available under many different brand names) and mild steel is easy to double flare with some practice with a harbor freight quality flaring tool. If not steel I'd probably look into oil rated Teflon hose
There is a fitting you can Get that screws onto your stock trans lines and has a flare on the end to help hold the rubber hose on. Got mines from Dave Husek when I bought his converter and cooler.


Well-Known Member
The transmission lines going to the cooler have about 50 - 60 psi max trans pressure in them during 1st gear wot launch , and less than that in 2nd & 3rd . I log pressure from the trans to the cooler , so it's not high pressure that you have to worry about .