Master Cylinder Brake Lines - 1967 Chevelle
Simplicity is the hallmark of genius. At least that’s what I’m told. In brakes, simplicity leads to a trouble-free system. Fewer joints and fittings reduce the possibility of leaks and failure points. Though, sometimes you’ve got to weigh the aesthetic as well.
That was the choice I was faced with when it came to plumbing the brake master on the Chevelle. The proportioning valve was very accommodating. It offered two front brake ports. In theory, the absolute best way to plumb this would’ve been to run a hard line from each port directly to the frame tab where it transitions to flex line to feed the caliper. For a total of six potential leak points. Four double-flare fittings and two AN fittings. However, one of the ports to serve the front is located on the top, front surface of the prop valve. Making it a very tight and somewhat unsightly brake line, right in your face.
I opted to plug one of the front brake ports and run a single line from the bottom port as an OEM proportioning valve for this car would’ve had. Since the lines run down to the frame, this was the most direct path to their final destination. That single front line runs down to a tee on the frame with a hard line to each front wheel. All in all, a total of eight potential leak points. 6 IFF and 2 AN. The way I figured it, if it was good enough for the factory, I could manage it. Speaking of the factory method of routing front brake lines, it will make you scratch your head and ask, “why?”
That was exactly my initial reaction to seeing how the General routed this chassis line. The thing is, I wanted this car to look as much like a restored (or original) baseline car that was modified. Though being that if someone really, really wanted to, the modifications could all be reversed. In reality that will probably never happen but it’s possible.
Something that puzzles a lot of people about master cylinder lines are the sometimes funky shapes they take. The reason for this is to absorb shock and movement in the lines. The beginning of the line is fastened tightly via the flare fittings into the prop valve. The junction tee is secured to the frame rail. The wild card between the two is the body bushings. In most cars, the body is not solidly mounted to the frame. As it travels down the road the body wobbles, bounces and flexes independently of the frame. This means certain doom for flared lines that span between the two, unless they have a place that is also flexible.
That, friends, is what this article is about. I like to make those little moonshine still looking loops to give my hard lines a little spring. I also like to try and make brake lines look as much like they were installed at the factory as I can.
A lot of folks like to use stainless brake line on their projects and it is dynamite looking when they’re finished. I haven’t ever had great success with making good, clean double flares on stainless. It’s very hard and sometimes a little brittle to cajole into such a shape. Maybe my flaring tools could use replaced? But I like to do a lot of the last flares on the vehicle with a hand-held tool.
On this project I chose to use rhino coated steel 3/16” line from front to back. All flares made were done as 45 degree double flares with adapter fittings where they transition to AN3 for the flex hoses. Something that I’ve found that works very slick to make a section in hard line, is an old section of exhaust pipe or large conduit. At about 2-2.25” in diameter, the loops are loose enough to avoid any kinks and they provide a decent amount of cushioning with 3 turns.
I suggest getting an extra piece of brake line to experiment with until you’re comfortable with your results.
In my efforts to replicate the factory routing on these lines, I found that there were places I couldn’t get access to in order to anchor or tighten the lines. You’ll notice the removal of the driver’s side upper control arm in some photos. On both sides, there is a tightly tucked steel line that runs under the rear pivot of the UCA. A great place to tuck it away and keep it safe from getting smashed. Not a great spot to have to work in.
Since tight bends and creating new flares near them are a combination that usually results in much swearing and less than optimal work product, I suggest starting at the proportioning valve end of your lines with the factory installed flare on your brake line. I mark where a bend will be with a Sharpie and usually only work one or two bends at a time, using a tubing bender. Removing and installing the line many times in the process. As I work away from the master, the bends usually get less complex and more gradual. When I come to a point where a junction is needed, that’s where I cut and flare the line. Don’t forget the flare nut. That’ll ruin your night. Or at the least, make your perfectly tailored line tighter than you’d planned after you have to cut the flare off and do it again.
The photos below show the line from the prop valve to the frame tee being fitted up and marked for a cut and flare. There’s no substitute for experience. If it’s your first time doing this, you’re going to screw up a lot of line. Keep after it. You’ll get better.
Next time I’ll cover the handy little flare tool that I used to make all the 3/16” double flares on this car.
