Are stainess and carbon steel "dissimilar metals" re: electrolysis?

[sixdogs]

My small street rod has a steering shaft with a stainless steel u-joint. As a safety system the u-joint has threaded holes to use set screws to lock the steering shaft in place. Trouble is, I can't find stainless set screws and there is not enough room to use a stainless bolt. Note here--I add a lock nut to hold the set screws in place.

I would prefer not to use anti-seize Because of the potential to get it on my interior.

So, will carbon steel react with stainless steel? Will anti seize stop the problem? Any other ideas?

 

[Mickey_Fx]

Nice you are at least concerned about the reaction of dissimilar metals that are in contact. Since you've not mentioned the series of SST you're talking about, can't say for sure what if any problems you might see.

Not sure what you mean by anti-seize. It is not uncommon to use a thread locker like Loc-Tite to help with preventing corrosion in threads. I'd use either 222 or 242 for this. The 242 is a little stronger in its "holding" ability so I'd use that if you are concerned about the set screw backing out.

 

[sixdogs]

Nice you are at least concerned about the reaction of dissimilar metals that are in contact. Since you've not mentioned the series of SST you're talking about, can't say for sure what if any problems you might see.

Not sure what you mean by anti-seize. It is not uncommon to use a thread locker like Loc-Tite to help with preventing corrosion in threads. I'd use either 222 or 242 for this. The 242 is a little stronger in its "holding" ability so I'd use that if you are concerned about the set screw backing out.

I have both 222 and 242. Would that form a barrier to protect against a problem? Only one set screw sort-of concerns me because there is not enough space for a lock nut. What about coating it with women's clear nail polish? I've done that with other things.

Anti-seize is just the normal silver colored paste to use when assembling dissimilar metals.

 

[the old grind]

Marine retail centers often have SS set screws to be used with boat railings etc, tho' those are usually just 1/4"x20s of different lengths. Most any tooling supply house (Grainger, McMaster-Carr, Fastenal) will have other sizes & they're easy to find online. Boaters will be familiar with how bare SS nuts/bolts will gall or seize on themselves, esp when power driven & allowed to heat up by friction (BTDT), but I'd use them for anything exposed to weather or road conditions.

SS alloys aren't entirely non-corrosive in all uses, tho' determined by proportions of nickel & Chromium they are stain resistant to varying degrees. +1 on using Locktite with SS. You'd see why when tightening or disassembling anything SS & you aren't breaking stuff as you go.

btw: In my shop, I don't like stainless one bit. It's hard on tooling and is difficult to get a good finish on without a bit of fuss. But, when fabricating or on the motorbikes I reach for off the shelf SS nuts & bolts whenever I can find 'em, & 242 is my 'go-to'.

 

[duwem]

Stainless and aluminum are bad in salt water (boat engines) so they put a chunk of aluminum on the lower unit called a sacrifical anode that will eat away ove time. Galvanic corrosion or something like that...

Even stainles bolts and stainless nuts can "gall" and not come apart, so some antisize it not a bad idea on them in some cases.

 

[jaotguy]

zinc anode

 

[sixdogs]

OK, I'm going with the Loctite on the threads. The thread size is maybe 3/16" and is a set screw.
Should I use 222 or 242?

 

[BeezFun]

So, will carbon steel react with stainless steel? Will anti seize stop the problem? Any other ideas?

There won't be any galvanic action between dissimilar metals unless there is an electrolyte. So it doesn't matter what you use.

 

[the old grind]

There won't be any galvanic action between dissimilar metals unless there is an electrolyte. So ...

So .. I'd avoid puddles, leave the street at rod home on days that might rain, and keep a dehumidifier in the garage. My reloading bench and shop machines are in the same room downstairs. Without a dehumidifier there, carbon steels (firearms, machine tables/chucks/vises/parallels/angle plates/some precision measuring tools) will rust without contacting anything else. (I don't suppose it's ever humid in Ohio .. )

One thing not yet mentioned is to fill set screw holes with silicone sealer, but not easy if they're sticking out with a locking nut on them unless you cover both completely. SS nuts/bolts/screws don't cost all that much, but you could save some $$ ...

 

[BeezFun]

So .. I'd avoid puddles, leave the street at rod home on days that might rain, and keep a dehumidifier in the garage.

OP states he doesn't want to use anti sieze because it might get on the interior of the car, which indicates u-joint is on the inside of the car. No need to avoid puddles or rain if that's true.

My reloading bench and shop machines are in the same room downstairs. Without a dehumidifier there, carbon steels (firearms, machine tables/chucks/vises/parallels/angle plates/some precision measuring tools) will rust without contacting anything else. (I don't suppose it's ever humid in Ohio .. )

Rust and galvanic corrosion are different things, OP didn't ask about rust.