This is the first bothersome fitting I ran in to on the rear brakes. The line is 3/16", which normally has a 3/8" 24 NF tube nut, however this nut is 7/16" 20 NF and threads into the ABS motor for the rear brakes. 7/16 tube nuts are normally used on 1/4" brake lines, but this one is bored for 3/16".
This is the larger 7/16" NF nut next to the standard 3/8" NF nut for comparison. Aside from the length of the larger nut, the diameter is the issue.
The 7/16" NF nut and 3/16" line go into this port on the ABS motor for the rear axle. I needed to make a line that ran from this port, back to the firewall and down to the frame and was going to use new 3/16" line, until I found out the issue with the 7/16" NF tube nut. My first thought was to get a brass adapter from NAPA, but there is no such animal.
Since off the shelf line would not plumb to the ABS motor, I needed to harvest part of the stock brake line or at least the tube nut that fits into the ABS motor. Since the section of rear line I saved from the ABS motor to the frame had roughly the right contour, I kept the line intact and flared the bottom end with the 3/8" flare nut from the back end of the rear line, where it goes into the axle hose. This way I could join the two pieces with a brass union.
I used a loaner flaring tool from the local parts store. I have the same tool at home, but broke the tip off the 3/16" mandrel a while back and have tot obtained a replacement mandrel yet.
And here we are with the newly flared line end, ready to mate to the brass union and plumb to the rear axle hose. I got a good flare on the second try, and broke the tip off the loaner mandrel as well. The guy at the parts counter didn't seem to worried about it when I told him. He said it was a warranty part.
I thought the front line from the proportioning valve would be easier, but no such luck. This little line goes between the proportioning valve and a longer line that runs down to the frame. The male end is the larger 7/16" NF nut like the ABS motor line, but there is a female nut on the other end, also 7/16" NF that mates the inverted flare line to a bubble flare on the longer piece that runs to the frame. Of course, the frame end of that line is standard 3/8" NF.
Yup, so much for easy. Since I broke the mandrel on the loaner flare tool, I reshaped the two pieces of line for the front, to parallel the rear line to the firewall and down to the frame. The lines are not nice and straight, but they are not kinked and are sealed tight. At some point in the future, I will get a better flaring tool, harvest the oddball fittings I need from these lines and make some nicely formed lines for the engine compartment to frame runs. For now, I just need some separators and a mounting tab. The basic shapes are there, so I have a foundation to work with now.
-Joe