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I've already tried googling with no results.
Here is the problem in question form:
Is there some rule or eng'ring concept or standard to indicate that the the tubing must be of DISsimilar material from the seat material???
Or to put it another way, Is it ok to mate steel tubing with double inverted flare to a steel seat in a fitting or casting etc. Steel to steel.

Can someone give an example of say a steel to steel or brass to brass etc.
I cn not recall any applications over the years where steel tubing with a double inverted flare ever mated to a steel item orr steel fitting. They are always dissimilar metals. No??

Not quite the same materials but I can think of one hard to hard connection. The rear brake tubing which clips over the rear axle connects directly into the wheel cylinders. That is typically steel to cast iron so both are hard. Whether one of those would be considered a softer material is a question. I'm trying to remember if the fuel tank outlet swaged into the tank is steel or brass but I think at least one of my Packards used steel. If so there would be a steel to steel application. Aren't most high pressure hydraulic connections such as used in lift cylinders steel to steel?

Since the mating surfaces (steel to cast iron in Howard's example above) are dissimilar AND the forces involved are not that extreme, my engineering background and actual experience with hundreds of cars tells me that it does not make any significant difference.


Been there, done that, have the T-shirt.

Craig

I chequed my 56 Exec. It has brass ends on the front brake hosess that the steel line screws into. Of course the brass junction block at the rear axle.

No problems with the Packard. HOWEVER i have a replacement rear hose for a 89 S10. Bought it BRAND NEW in a packarge at one of the major auto chains. It is ALL STEEL on the fittings. OEM is all brass. See the pics.

NOTE that altho the hex portion of the OEM is steel, the actual contact surface of the seat for the flared tubing is brass.

THe second pic shows a better view of the brass seat with the steel hex to which a magnet is attached and resting on mine index finger.

THE PROBLEM is that with NEW tubeing with manufactured ends and the new Duralast brake hose with an ALL STEEL seat will not seal. It leaks pretty bad.

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I finally got the sunlite just right. The rusty one is OEM. (on the left). The brite shiny one is the replacement. Also note that the OEM has rather deep recess below the conical seat while the new replacement hose has a seat that is very shallow.

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To me just common sense says that to get the highest possibility of a perfect seal you'd want one surface to be softer than the other so if needed they can "swedge' to a tight seal, whether they are dissimilar metals or two different steel alloys.

Yes Owen Dyneto. That's what i'm thinking too. I've checked 2 other discount auto parts chains, AAP and Rilly but thay all seem to offer only all steel fittings on the ends of the hose. There is a Wagner (the ONLY long time popular name brand offered) that has brass both ends. But the branch end at the axle is 'banjo' type. Not a major problem to make the change for the bolt and copper washer seals.

The only reason i brought up this rather non-Packard experience is incase others run into the same situation when replacing their Packard brake hoses with any of various "replacement" type parts regardless of source.
Just one more detail to watch for in parts.

Since it's an SAE fitting, that's a good place to get the answer.