I like AN plumbing. The fittings date back to the 30s and while they did not see a lot of service in traditional hot rods they were available and that p***es my muster. I also like the concept of running brake lines through the frame. But I don't care for those stainless steel street rod things and the nest of tubing that they create on the inside of the frame rails. So, I did a little conceptualizing and some web searching and came up with an alternative that requires a bit of very basic metal lathe work and some welding. The "through the frame part" is simply some 5/8" mild steel round stock. The length is the distance between the outside of the frame rail and the face of the boxing plate plus 1/2". When placed in position the "core" piece projects 1/4" on each side. This allows welding without distorting the sealing surfaces on the end. The core is cut a little long and faced to length with cuts on both ends. Both ends of the core are bored and tapped to 3/8"-24. A bottoming tap is used and the depth is carefully controlled to minimize any possible air pockets. I allowed the thickness of a copper crush washer for tightening down. The core was through drilled with a 1/8" drill bit. The key to this approach are the -3 AN fittings (3/16") that I used. I found them at Pegasus Racing in their plumbing section. The double ****** banjo fitting is a hard to find item as is the straight ****** with the copper washer sealing surface. http://www.pegasusautoracing.com/ What do you think?
Pretty slick! Any reason not to use a piece that is tapped all the way through? I can't imagine any air bubbles would get too stubborn in there.
StreetRodder had an article recently on the subject. Seems like some folks were having trouble getting air out of their conventional through the frame fittings. So I simply tightened up the tolerances. Not that difficult.
Would it be possible, or is there enough meat left on the outside of the "pipe" to run a dye down? that way being able to use a jam nut on each side instead of welding? Maybe that would kill a smooth look but it would make it easier to repair incase of some bad luck.
Slick, yup, but you might have to go to a thicker material so as not to thin it down too much with OD threads, Or make a complete piece from bar and have a flange on one side and OD threads on the other. That way you could have a 3/16 hole in the middle, too, for fluid transfer, instead of the almost 3/8 ID. And Bib, great idea and cool pieces. Isn't it really -3? Frank
When tapping with pipe thread you cannot tap very deep as the threads are tapered, the deeper you go with it, the looser the fittings will be...
The article mentioned above made the point that if the hole thru the fitting was larger than the brake line tubing you are using there was a problem with the brakes feeling "Mushy", when the diameter was brought back to the line size this Mushy feeling went away. Bob Vinton BigSkyBob
Yes, AN -3. My bad. The 3/16 line is OD. The p***ages through the fittings are 1/8" so that is what I used for my through bore. I think the 5/8 rod could handle a fine thread on the outside. But you don't want to compromise the sealing surface. There are a lot of variations to this technique. The key point here is the availability of the fittings and the fact that you can do something other than "store bought."
The threads on both ends are straight threads, hence the need for the crush washers. He didn't use any tapered pipe threads.
Yes, let's all buy everything from Speedway. Seriously, the guy knew what he wanted and built it to suit him. If you don't like it, just move on, no need to dump on the guy's project. To the OP, I agree about the AN fittings. I pretty much don't do any double SAE flaring anymore, because I've transitioned completely to AN tube fittings. They're a hell of a lot easier to deal with, that is for sure. Indeed, but taps that long are expensive, and single pointing those threads would take forever. On top of that, threading the entire ID is not necessary. Rule #46 when doing machine work: Don't remove any material that you don't need to.
Great idea.Might just have to steal it! Where possible,I prefer to fabricate parts rather than buy them in.
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