Assembling a GM Trans Cooler Line Kit - 1967 Chevelle
If you’ll recall my tirades in the past about my dislike for making steel hard lines, you’ll also recall that the ones I do generally come out pretty nice. That’s a sham. They came out nice because those lines are all in very accessible areas and didn’t need to snake through a bunch of other obstacles. Obstacles that are hot, or dangerously sharp, or spinning I built those brake lines on the workbench with careful measurement and trial and error (many errors).
As a teenager building my disco Nova, trans cooler lines were my first experience with scratch building a set of lines. To do them cleanly, parallel and safely routed, is a work of art. If you can make them well, Congratulations Rembrandt! My stuff looks like a Picasso. A little off, asymmetrical and weird. Fortunately, I started stocking a stainless braided kit from Gotta Show a number of years ago. We sell a lot of them. Now I see why.
The kit contains a length of PTFE line with 2 pre-terminated ends, flare to ANfFittings to engage the fittings in the transmission and 2 AN fittings to hook to elbows at the radiator.
I had not, to date, assembled any PTFE hose or fittings. As I found out there’s not much to it, but you definitely need to plan out your cuts and follow steps carefully to get nice results.
I started by figuring out my routing and just how long the longer hose would be. Since both ends are pre-terminated, you’ll need to carefully measure how much you’ll need for both lines. I found that there was plenty of extra, but you’d hate to get caught short if your car is longer or you routed them differently.
One thing that’s indispensable is strong, high quality electrical or stranded packing tape. Before you try to cut the hose, wrap it in tape to hold the braided fibers in place. If you don’t, it’s a lot like making a perfect double flare on a hard line and remembering that you forgot to put the flare nut on first.
Taping the braid also helps minimize how much you’ll bleed. I mean, you’re still going to poke your fingertips and you’re going to bleed. Maybe just not as much if you use the tape wisely. Yes, that’s my blood on the body washer in that photo. I regret nothing.
Do you have the spot you want to cut all taped up? Good, now you’re gonna think I’m crazy, but find the sharpest, heaviest, straight cold chisel you have and a big hammer that you’re really good with.
I tried the hose/cable cutting shears and they worked once, really well, but the stainless ruined the cutting edge and that was that. Now a couple of strands always slip between the blades.
The heavy chisel method (or a Beverly shear) work quickly, don’t melt the Teflon like a cutoff wheel and it doesn’t leave any debris inside the line. Use a thick plate of steel or aluminum on the floor, set the hose in place, square off with the chisel and hit it HARD, one time.
Once you’ve made the cut you’ll see that the line is made from a thin walled Teflon tubing and a steel braided outer casing. Sometimes there’s a thin liner membrane between the two. In essence, the fitting connection is just a compression fitting. There’s a compression ring that captures and retains the inner line and an outer nut that retains the braided sheath.
I used Fragola fittings at the radiator with Speedway Motors flare to AN adapters. The Fragola fittings are finished in black and have a graceful 90 degree bend incorporated.
Slip the outer collar nut over the tape and remove the tape. I found that a little screwdriver worked well to spread the braid away from the wall of the plastic inner tubing. This is the part that will make you bleed. Be careful. After you’ve made enough room to slip the collar onto the tubing, insert it between the layers with the chamfer facing away from the fitting joint.
After you’ve ensured that the compression collar is nested completely on the Teflon tube and the braid is covering the outside of it, you can mate the halves of the fitting. I found later that a little dab of anti-seize at this point helps a ton with tightening the joint.
This step is much easier in a bench vice with AN jaw liners, also learned later. I didn’t want to disassemble the connections that were already finished at the transmission. So I terminated the radiator ends on the car.
All in all, the lines were easier to finish that I anticipated. I think I have the confidence needed to tackle the custom power steering hoses.