Bending Brake Lines by Jim Clark

 

 

How To Accurately Bend Lines
Story & Photos By Jim Clark (The Hot Rod MD)

Copper, aluminum and mild steel tubing is relatively easy to bend which allows for correcting some mistakes when you bend it in the wrong place. Stainless steel tubing is not so forgiving; when it is bent that is it. So you have to be more accurate when measuring and calculating each bend.
Creating straight lines from one point to another or lines with a simple 90° bend are very easy to fabricate but most lines on a brake or fuel system have to snake around components on the vehicle before reaching their destination. Mocking it up with a soft length of copper wire creates a pretty good rough template as a guide. However, if you want a really professional looking job you have to calculate the angle for each bend and path that the line will take.
The front brake crossover-line on my roadster seemed like a simple task but actually required multiple angles to route it cleanly along the backside of the front crossmember. A straight line across would have been 22-inches long with two 90° bends at each end. But there had to be a step in the center to form around the spring u-bolts and two compound angles traveling upward at 15° and to the rear 10°. To complicate it even more the ends bent downward at two different angles so that they could meet up with the fittings.

 

 

Bend Line MD-1

 

This simple brake crossover line has multiple angles and a step in the center to clear the u-bolts. A length of copper wire used as a mockup allows the clamps on the crossmember to be installed first, which simplifies the job.

I used a combination of tools to make the bends after making the wire mockup and mounting the clamps on the crossmember. The project was more difficult because the engine was already installed but this made sure that nothing would interfere with the other components. The use of an angle drill made this installation possible.

A pair of V8-806 3/16-inch bending pliers and an Imperial lever-type tube bender provided the tools for all of the bending while a variety of measuring and cutting tools were needed to complete the job. You may have others in your toolbox that will make the job simpler.

 

Bend Line MD-2

Bend Line MD-3

 

The wire mockup allowed placement of the line clamps before bending the line. Holes were drilled for the mounting screws using an angle drill to get into the more restricted places.

Holes are then tapped for the stainless Allen screws provided with the Kugel Komponents stainless steel line clamps. Clamps were also supplied with stainless steel Phillips-head screws for use on sheet metal applications.

 

Bend Line MD-4

Bend Line MD-5

 

Stainless steel clamps are then installed holding the wire mockup in place. Now the mockup can be fine-tuned to follow the desired contours for the finished line.

I cut a length of tubing a few inches longer than needed to compensate for the bends and started in the middle with the step around the u-bolts. I measured the width across the u-bolts and calculated the 45° bends using the chart supplied with the bending tool. After making the two 45° bends I marked the center of the second bend and figured out the angles needed to follow the angles on the crossmember. A line drawn on the crossmember gave a reference to measure with a protractor/angle finder. The second bend was so tight that I had to make the bend using 3/16-inch tubing bending pliers. Check the bends against one of the angle finding tools (see photo).

Line had to step around the u-bolts that hold the front buggy-spring inside the front crossmember.

 

Bend Line MD-6

Bend Line MD-7

 

Overhead view shows how the line steps around the u-bolts with very uniform 45° bends.

Now that the line was bent to follow the contours of the crossmember I could lay it across the frame and mark where to make the 90° bends at each end. The line on the right had to be bent at 90° and angle down at 30°. I clamped the center offset flat on the bench and rotated the bending tool to 30° using the protractor/angle finder and made the 90° bend. I repeated the process at the other end with a 90° down bend and another 90° bend to the rear; offset 2-inches.

Bend on left side had to turn down and then follow parallel to the frame connecting to the T-fitting going to the left side front brake.

 

Bend Line MD-8

Bend Line MD-9

 

Bend on the right side descended at a 30° angle and connected to the 90° fitting going to the right front brake.

The final step was flaring the fittings at each end. There was enough line left to cut and flare it at each end. If the fittings fit closer to the bend I would have had to flare the fitting at one end and calculate the length for each segment, working my way to the other end of the line, using the chart supplied with the bending tool. It’s possible and sometimes necessary to do it this way but you will have to be very precise when calculating each bend and angle. The same procedures apply when bending any of the variety of lines on a vehicle and will look very professional if you take your time and plan before acting.

Finished line follows the contours of the crossmember and mates up to the fittings for the front brake hoses.

 

Bend Line MD-10

 

Operating instructions for the lever-type tube bender.

 
 

Bend Line MD-11

Step #1: When placing the tube in the bender, raise the right handle of the bender as far as it will go so that it rests in a horizontal position as shown. Raise the clip and drop the tube into the space between the handle slide block and the bending form.

Step #2: Drop the clip over the tube and turn the handle slide-bar about its pin and press to the right as shown. Note that the zero mark on bending form will lineup with the mark on the slide-bar. Black mark on the tube that is lined up with the “R” is the center of the radius for the bend (See offset bending instructions and diagram).

Bend Line MD-12

Bend Line MD-13

Step #3: Proceed bending the tube to the desired angle by aligning the 0-line with the appropriate angle indicated on the bending form. Bends up to 180° may be made with this tube bender. To remove the bent tube from the bender, lift the handle slide-bar back to its horizontal position shown in step one and raise the clip. Tube is then free and can be removed from the bender.

Angle can be verified by checking it against a combination square/ruler or other angle-measuring tool. Bending tool is pretty accurate but you should fine-tune the angle after making the initial bend.

Bend Line MD-14

 

                        Bend Diagram

Step #1: Determine the total amount of offset required (dimension “Y” in diagram) and angle of offset. Whenever possible use 45° offset bends. This will enable you to figure the total amount of tubing required for a given application as explained in the section on: How to Figure Length of Tubing required for 45° offset applications.

Step #2: Figure the length of tube that is needed to meet your offset requirements (X in dimension diagram) from table below. For example: Say the amount of offset you require (“Y” dimension Step 1) is 2-1/2 inches and the offset angle is 45°. Check the 45° column and find 2-1/2 inches. The figure next to this is the amount of tubing required for the offset bend you want (“X” dimension). In this case it’s 3-17/32 inches.

Step #3: Determine where you want the center of the offset on the tube and make a reference mark (A). Now measure off the “X” dimension (determined in step 2, example 3-17/32 inches) starting from the reference mark and make a second mark (B). You are now ready to make the bends.

Step #4: Align mark (A) with reference mark (R) on bender and proceed with the first bend. Then align (B) with “R” mark and make second bend in proper direction.

 

How to Figure Length of Tubing required for 45° offset applications.

Determine the “X” dimension required for a particular application and subtract the amount of offset from this. From the example above (step 3) 2-1/2 inches offset were required and the “X” dimension as determined from the table was 3-17/32 inches. The difference between these two figures is 1-1/2 inches. Simply add this to the vertical distance from the starting point to the finishing point (“Z” dimension in illustration above).

 

Note: When the amount of offset exceeds what is listed on the table, choose an offset from the table that is a multiple of the offset that you need. Look this up on the table and multiply the “X” dimension by the multiple you used. Example: For an offset of 20-inches with a 45° bend. Look up 5-inches offset on the table in the 45° column and multiply “X” dimension (7-1/16 inches) by 4. The resulting “X” dimension you would use is 28.     

Click on the chart for a larger  printable image. 

Offset Bend Calculator

 

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