Quote:
Originally Posted by Cloverdale
Could you explain the metallurgical reason's why using a stainless bolt with loctite is not usable in this application?
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You didn’t answer my question, you only asked me one. This feels like the elementary school playground when a kid says “I know you are but what am I?”
But I’ll play along and answer your question even though you don’t have the courtesy to answer mine. So I have to admit I’m not a metallurgist only a hobbyist and therefor I rely on what BMW gives us in their technical manuals and assume they do their homework. And then I can also sometimes learn something by Google too lol
This is an except from the bmw technical info on the N52:
What I have circled there reads:
“The aluminum bolts are needed to prevent contact corrosion. Conventional steel cannot be used in magnesium for any reason. The aluminum bolts can be identified by a blue colored bolt head and their light weight.”
Then when I Google I find there are many charts like this online and the basic premise is the further apart the materials are the more reactive they are together.
Aluminum and Magnesium are near the top while stainless is in the middle and titanium is near the bottom.
Mild Steel, Alloy Steel, and even Cast Iron are all actually closer to Magnesium than stainless is on this chart so any of those would actually be preferable to stainless even though none are acceptable according to BMW.
(And interestingly Titanium is third from the bottom so actually very reactive with Magnesium so would probably be the worst fasteners to use on n52 not that anyone asked.)
So how about you answer the question I asked and also why BMW would go to all the trouble to explain this to their Techs, and also why BMW would even bother to manufacture Alumimum bolts in the first place when they could have just said “use loc tite” with any old crap fastener in their manuals?