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© 2000 Brian F. Schreurs
Even we have a disclaimer.

Since this poor truck had the wrong transmission in it, buying brand-new lines from the dealer seemed like an expensive proposition that probably wouldn't work anyway. So we set out to fabricate our own. We bought a flaring tool and a tubing bender -- the kind that looks like a weird set of pliers, since the bending will have to be done under the truck -- and a couple lengths of 5/16" steel brake line. The longest that we could find anywhere was 60", so that's what we got. The Rayloc part number is STD560. Then we crawled under our 1974 Dodge 100 pickup and got to work.

Odds are, if you're doing this project, your vehicle is already in the air by some means. We prefer ramps for this kind of work, and that's what ours was on.

Remove the old trans lines. They're held in place at four locations: two at the radiator and two at the transmission. Each fitting is 5/8". They will all probably weep trans fluid so be ready for that.

After disconnecting the lines, it's simply a matter of maneuvering them out from under the truck. Keep at it; sooner or later, they'll come out.

Set the lines on the floor and measure each one to make sure you got enough of the new tube. Guess what? You didn't. The way Dodge engineered this mess, the furthest-forward fitting on the transmission goes to the nearest fitting on the radiator; the furthest-rearward fitting on the transmission goes to the furthest fitting on the radiator. Therefore, one line is pretty short and the other is pretty long. Longer than 60", which is the longest piece of brake line available.

This leaves you with two options. The first is to buy more line and connect them up. The problem with this design is that it introduces another opportunity for a leak. It also looks dumb. The second is to reverse the flow of the transmission cooler, thereby reversing the destinations of the trans lines, and averaging the two lengths so that they are both under 60". But is this possible?

We researched this question extensively, checking with several master mechanics, textbooks on automatic transmissions, factory service manuals, and websites. Everywhere we turned either didn't discuss it or said that as long as it's a horizontal cooler (which it is) then it shouldn't matter. So we reversed it.

By now you've probably noticed that the brake fittings on the brake line look nothing like the trans fittings on the trans lines. If you think you can run off to the local Dodge dealer and buy new fittings, you're wrong; they only sell them as part of the lines. Well, our original fittings looked okay so we cut them off the original lines and reused them. That's when we discovered that part of the previous owner's lovely handiwork included copper tube! Don't be a chump like this guy -- copper is totally unacceptable in an automotive application because it fatigues way too fast for the harsh environment it must survive.

To get them onto the new line, cut off the flared end on one side. You're going to be cutting more off in a bit so don't worry about it. Slide off the two brake fittings and put one of the new fittings on the line. You don't want to put both on yet because they won't slide around the bends you're about to make. The second fitting has to go on last.

The old, crappy, redneck lines on the left; the new, cool, hand-fabbed lines on the right.

Now for the tiring and time-consuming part: bend the lines. We can't help you much here; you're on your own. Take your raw line, your tubing bender, and yourself to the underside of the truck. Measure, bend, test-fit. Measure, bend, test-fit. Measure, bend, test-fit. Remember to think in three dimensions. It's actually pretty cool to watch the tube take shape. At first you won't be able to attach the tube to the transmission, but eventually you will; this makes it easier to visualize the next bend.

Tired yet?

When you finally reach the radiator fitting, keep in mind that it needs to approach the fitting nearly straight-on for a good seal. Bend accordingly. Odds are there will be a few inches of excess material. Put a little masking tape where it reaches the rad fitting and mark it to be cut. Remove the tube from the truck.

Back at the bench, cut off the excess material. Remove the masking tape. Slide the rad fitting on. It's time to flare the tube end.

Not to put too much pressure on you, but keep in mind that if you screw this up, you get to bend a whole new line.

Start by cleaning up the tube end. Try to make it as close to a perfectly flat cut as possible. Then chamfer it (make the edges tapered). Follow the directions on the flaring tool to make the flare, but one thing we can tell you: with this steel, don't be afraid to overtighten everything. It's tough to work with.

So how's your flare look? Well, it's too late now -- might as well try it out. It could still seal even if it is a little lopsided. Go install your new transmission line.

Now do the whole thing again for the second line.

Once you've bent, flared, and installed both lines, lower the truck, start it up, and check the transmission fluid level. Once that checks out, you're done!

Yay! You have new lines! Now what? You won't see any performance difference... you can't amaze your friends (unless your friends like to crawl under trucks)... so what's the point? Well, the point is pride in craftsmanship and the knowledge that it was done right. And that's why we do this, isn't it?