stainless bolt threaded into aluminum

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o0norton0o

o0norton0o

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I finally broke down and bought the braided oil lines with the stainless cap head banjo screws, and I have a question.

Does the fact that the head and the bolts are dissimilar metals necessitate some sort of loctite fluid on the threads? I wonder if their different expansion rates make that necessary. Anyone?? Bueller???
 
I have stainless oil line and bolts and its never been an issue. They stay put all on their own once tightened. Don't over do it as they are in alloy and being banjo bolts are hollow but they should be capable of "reasonable force" enough to seal and thats it job done. Careful routing of the pipe (as many have advised often before) is important to prevent it damaging or pulling things or things damaging or pulling on it (that would maybe cause fittings to loosen).
 
o0norton0o said:
I finally broke down and bought the braided oil lines with the stainless cap head banjo screws, and I have a question.

Does the fact that the head and the bolts are dissimilar metals necessitate some sort of loctite fluid on the threads? I wonder if their different expansion rates make that necessary. Anyone?? Bueller???
Click to expand...

Personally I always use a little copper grease on the threads of stainless fasteners.

Regards

Esme
 
o0norton0o said:
I finally broke down and bought the braided oil lines with the stainless cap head banjo screws, and I have a question.

Does the fact that the head and the bolts are dissimilar metals necessitate some sort of loctite fluid on the threads? I wonder if their different expansion rates make that necessary.
Click to expand...

No, not where braided oil lines are concerned as the internal oil pressure will keep the threads 'lubricated'. Expansion doesn't appear to be a problem as the original bolts were steel and I doubt any difference in expansion rate at that diameter (5/16") would matter.
 
And stainless, being a bit more stable (less corrosion-prone) than regular steel is less likely to participate in galvanic reaction, which is the crux of the biscuit with dissimilar metal contact.
 
Danno,
FWIW
From my experience any time dissimilar metals are attached to each other some sort of anti-seize should be used. I agree with LAB that it may not be necessary on that banjo. Under the wrong conditions SS and aluminum can be a toxic combination. I have seen a stainless bolt pull the threads out of aluminum on disassembly with nothing but white dust remaining. It's cheap insurance to coat a bolt before assembly. Anti sieze also saves wear and tear on threaded holes that are taken apart frequently. Thread locking compounds are handy because you can bolt things together without being in full tension (carb tops, coil bracket bolts, valve covers) and seal out water and other liquids that can cause corrosion.

Pete
 
Danno said:
And stainless, being a bit more stable (less corrosion-prone) than regular steel is less likely to participate in galvanic reaction, which is the crux of the biscuit with dissimilar metal contact.
Click to expand...

Sorry Danno, I have to take issue with your post.

Stainless is a bit more galvanic reactive with aluminum than plain carbon steel.

Refer to a previous post of mine that gives a metals compatibility chart.

how-install-stainless-studs-bolts-t25290.html?hilit=Stainless%20aluminum#p334192


Slick
 
I worked in a machine shop for many years in a very large hospital. Because of the intense sterilizing procedures that our equipment went through the majority of the fastners were stainless threaded into aluminum bases. We always used a bit of neverseize or Teflon on all of the threads. Teflon if the equipment was to be used in an oxygen rich environment. Periodically we would come across an example that didn't have the threads treated. 50/50 on thread survival. I got pretty good at heli-coil installation.
 
Deets55 said:
Danno,
FWIW
From my experience any time dissimilar metals are attached to each other some sort of anti-seize should be used. I agree with LAB that it may not be necessary on that banjo. Under the wrong conditions SS and aluminum can be a toxic combination. I have seen a stainless bolt pull the threads out of aluminum on disassembly with nothing but white dust remaining. It's cheap insurance to coat a bolt before assembly. Anti sieze also saves wear and tear on threaded holes that are taken apart frequently. Thread locking compounds are handy because you can bolt things together without being in full tension (carb tops, coil bracket bolts, valve covers) and seal out water and other liquids that can cause corrosion.

Pete
Click to expand...
This has been my experience as well. Over enough time stainless and aluminum can bond very well.
My1972 Trials bike wheels are laced with stainless spokes and aluminium nipples. When doing the resto on the bike I thought that trueing the wheels up a bit would be easy since spokes and nipples looked as new. It turned out that electrolytic action had welded every spoke solidly to its nipple.
 
texasSlick said:
Danno said:
And stainless, being a bit more stable (less corrosion-prone) than regular steel is less likely to participate in galvanic reaction, which is the crux of the biscuit with dissimilar metal contact.
Click to expand...

Sorry Danno, I have to take issue with your post.

Stainless is a bit more galvanic reactive with aluminum than plain carbon steel.

Refer to a previous post of mine that gives a metals compatibility chart.

how-install-stainless-studs-bolts-t25290.html?hilit=Stainless%20aluminum#p334192


Slick
Click to expand...

+1 on this;

Worked at ALCAN R&D for many years. Aluminium + stainless steel = galvanic reaction and corrosion. Teflon washer between the two should work.
 
Danno said:
And stainless, being a bit more stable (less corrosion-prone) than regular steel is less likely to participate in galvanic reaction, which is the crux of the biscuit with dissimilar metal contact.
Click to expand...

While I agree with what you have said, you used the words 'less likely'. I would caution against making predictions about the reactivity of different metals with each other. Usually when there is chromium involved, there is nil reaction. I use stainless bits screwed into both aluminium and magnesium and have never had any problems. However years ago I was involved in making splash shields for a piece of equipment where metallic mercury was being used. On advice from a metallurgist we used aluminium. The shields grew copious amounts of whiskers and ended up a right real mess. Apparently people in the aircraft industry know about this - it can stuff an aeroplane.
 
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