ISO Metric Bubble Flare for Brakes Lines Made Easy
When you take on the challenge of building your own car, street rod, hot rod, rat rod, or performing your own automobile repairs, the more skills you have, everything becomes simpler. This is true when working on a house, technology, or anything else. One of the draw backs if you want to call it that would be the time element. The more you can do yourself, the project, whatever it might be, takes longer to complete. The advantage when doing work yourself, there is sense of satisfaction and pride, not to mention a financial saving. The financial saving is increasingly becoming a large factor when you look at how everyday living expenses are growing. Just one simple thing, the cost of fuel, both gas and diesel fuel have increased substantially in the last 3 to 4 months. The increased cost of getting back and forth to work is diverting money for recreation, hobbies, leisure, and all those other non-essential items.
Growing up without much money and having a father with many skills, I learnt how to do a lot. This sometimes is a bit of a curse, as everything takes just a bit longer to complete. As I see it, if you are intending to build a hot rod, why not learn how to do as much on the car as possible.
Now it’s time for me to install the brake lines on the 1929 Model A Ford roadster hot rod. There was a few ways I could tackle this job. I did have a new coil of 3/16” (0.1875”) steel brake tubing but I needed to purchase all of the fittings and straighten the brake line, not mention I would need to make the ISO metric bubble flares. Another option was to purchase straight pre-made lengths of brake lines with the correct fittings. This option seemed to make sense but none of the lines would be an exact fit on the 1929 Ford Roadster hot rod. Not wanting excessive amounts of brake lines on the frame or chassis, I decided that cutting them to the length I required and re-doing the flare was the best path for me. I am the sort of person that thrives on learning new things. This curiosity required me to learn how to make the ISO metric bubble flare.
My 1929 Model A Ford roadster hot rod has C4 Corvette suspension removed from a wrecked 1986 Corvette Indy Pace car. The brake components from this vintage of Corvette use the ISO Metric bubble flare. A few years ago, I purchased a rather inexpensive double flaring tool kit. As with most things, especially with tools, you get what you pay for. This kit was okay for making a single flare, but inverted double flares would never come out perfectly no matter how careful I was. I found that there was too much play in many of the parts required to make the inverted double brake line flare. Oh well, I couldn’t be too disappointed as I only paid $25 for the kit. Now there is good in everything. I found this same kit would make a perfect ISO Metric bubble flare every time.
Having the ability to make good ISO Metric bubble flares, I felt that purchasing pre-made brake lines longer then I required would be a compromise to this interesting hot rod task.
This first step was to plan a layout for the brake lines and then approximate the lengths of all needed brake lines. Then I went off to see my friends at NAPA and purchased what I needed to completed the job. My intention is to shorten the lines I purchased from NAPA to the exact length required for the 1929 Ford roadster hot rod.
In order to create perfectly shaped brake lines, I used 0.125 inch ( 1/8th”) wire and created the required shapes for all brake lines. These then became templates for the actual brake lines. Carefully measuring all of the templates, all brake lines were cut to size allowing an extra 0.25 inches ( ¼” inch) for the bubble flare. Once the tubing was cut, I used a soft wire wheel on the stationary grinder to de-burr the cut tubing. This is fast and produces a nicely finished cut tube. Of course you can also use the de-burring tool usually supplied with the flaring tool kit, but with the cheaper kit I purchased, I found that it did not work all that well.
The next most important step is to install the brake line fittings with the correct orientation. Now mount the brake tubing into the flaring bar such that the freshly cut tubing is facing the flat side of the flaring bar and the flat side of the flaring bar is facing in an upward direction. For 0.1875 inch (3/16”) tubing leave about 0.25 inch (1/4”) exposed from the face of the flaring bar.
For a quality flare, mount the flaring bar with the clamped tubing into a bench vice. This will prevent un-necessary movement during the flaring process and make the alignment of the flaring yoke and inverted flaring adapter button easier.
Once everything is lined up perfectly, tighten the flaring yoke onto the tubing. Do not over tighten the flaring yoke as excessive force will destroy the flare. It would be a good idea to make a few practice flares on some scrap tubing before making the bubble flares on brake lines that will be used on a car.
With the flare complete, remove the flaring yoke, inverted flaring adapter button, and remove the tubing from the flaring bar. I have noticed that the flaring process does reduce the hole opening on the tubing and would restrict the flow of brake fluid to a minor extent. To optimized the brake line, I use a 0.125 inch (1/8”) drill bit to ream out the hole opening. The brake line will need to be clamped in a bench vice for this optional step.
To make everything easier to visualize, I created a short video of making an ISO Metric bubble flare. Just click on the link below to watch the video.
Fast Tube by Casper
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Tags: 1929 Ford roadster, 1986 Corvette, brake line bending, C4 Corvette, Corvette brakes, DIY brake lines, flaring bar, flaring tool kit, flaring yoke, hot rod, how to do a bubble flare, how to make a bubble flare, how to make an ISO Metric bubble flare, ISO Metric, Metric ISO bubble flare, Model A Ford, Model A Ford Roadster, NAPA