I have to run some lines through some sheet metal. Two options present themselves:
AN Bulkhead Fitting:
-Expensive
-Two additional fittings to attach (which are also expensive, and each a potential leak)
-Made out of aluminum and can therefore snap if hit
-Requires periodic re-tightening of bulkhead nuts
-Can be disassembled
Steel hardline through grommet:
-Cheap
-No additional leak points or fittings
-Can't be disassembled
-Requires checking to ensure grommet is intact
Why would I go with the bulkhead fitting here? Seems like complexity, cost, and leak points with very little upside- somebody convince me otherwise, this has been a long standing internal argument for me and I really don't get it.
Do you need to disconnect at the bulkhead for clearance for other tasks?
Like removing fuel lines at top of bulkhead so you can get the starter out or something?
So far, I'm leaning hardline.
If you have to disconnect the line at the firewall on any kind of regular basis for servicing.
Audi ran huge AN lines back and forth straight from the engine/dry sump pump to the thermostat/oil tank in the trunk of the quattro rally cars, no bulkhead fittings. These were not regularly serviced items so no need to get fancy.
For brake lines, I absolutely would run bulkhead fittings.
Grommet wear lends the steel line to rub? I like bulkhead fittings and AN stuff in general, it's never leaked on me in highly vibratory vehicles(drag cars with solid mounts).
the ease of disassembly works well for me and it's easily adaptable to hard line with a flare, ferrule and tube nut. Maybe that's your stuff. A bulkhead with a drop of loctite and flare your hard lines to it. I have flared hard line front to back on the Datsun and flexy braided bits to the pump/tank/regulator and fuel rail
You can get steel bulkhead fittings. They are called JIC fittings and will interchange. I would go bulkheads since they look so much cleaner.
To me bulkhead fittings are about access in one form or another for maintenance or part removal. If you are going to need to access or move the line for any reason having a fitting gives you relatively easy/easier access. Cutting the solid line to gain access means putting a fitting there or replacing the line.
I may know someone with access to steel JIC fittings and a hydraulic hose crimper in their basement.
JIC are technically different because the thread form is different, but they thread together just fine. Just make sure you get 37 degree, and not 45 degree.
45 degree has another name I can't think of right now, is used for things like gas lines and other plumbing. Same thread sizes/pitches as AN and JIC, just to make things fun.
In reply to Pete. (l33t FS) :
45 degree are interchangeable except the 3/8 and 3/4 which have different thread sizes. The majority of steel fittings are going to be 37 degree, 45 is mainly in brass. But it is something to be aware of.
Typically called SAE 45, but then JIC can also be listed as SAE 37 degree.
In reply to EvanB (Forum Supporter) :
Yes on SAE 45. We call the 37's - JIC's.
Really depends on your use case. Like others have commented. If it's a line your running and will not need to move for clearance hard line it. Bulkheads are great for being able to remove lines for service. I used bulkheads in drag cars because we would remove the whole front clip for service. Pull a engine everything electrical or fluid forward of the firewall disconnected. Made swapping a engine easy as the spare already had all the wiring and lines attached. Just slide it in and attach everything at the firewall.
In reply to ¯\_(ツ)_/¯ :
You'll find out that one long line is much harder to work with than a bulkhead fitting and shorter lines. If you have trouble with leaking at fittings you're doing something wrong.
Every leaky braided hose I have seen was built poorly. Properly installed bulkhead fittings should not loosen up regardless of the material they are made of. Yes they are expensive, but the serviceability is usually worth the price.
Steel AN bulkheads for $5 each.
I wouldn't say that would break the bank. Unless you want a size bigger than the AN-6.
