Loctite primer necessary?

fafrd

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I’m gearing up to secure my first stainless grubscrews into aluminum 280Ah terminals with Loctite Red and see that the instructions state that Primer is needed when both surfaces are ‘inactive metals.’

Stainless is an inactive metal and so is Aluminum, so it seems like primer is required.

But I believe I’ve heard from many who have used Loctite Red on this board that primer is not needed if you have cleaned the threads with Acetone (which I have done).

So advice for a Loctite-newbie appreciated - do I need to bother with primer after threads have been cleaned with Acetone and dried?
 

Q-Dog

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I personally don't think the loctite is necessary, but, do whatever makes you sleep better at night.
 

fafrd

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I personally don't think the loctite is necessary, but, do whatever makes you sleep better at night.

Oh, I’m way past that. Already stripped my first thread which I am still in the process of recovering from.

Moving all terminals from female threads to male grubscrews and want them permanently affixed (never going to remove these Grubscrews).

Already secured a few with JB Weld but that is very slow and tedious and Loctite reportedly works as well for securing grubscrews but is easier to install.

So my question boils down to whether I need to use primer when securing stainless grubscrews into aluminum terminals or whether cleaning with Acetone will work as well...
 

Bob B

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it always amazes me how people want to inject their opinion even though it has nothing to do with the question.

I personally always try to do what has the best chance of giving a good result .... in this case, it would be to use the primer. I think the acetone in the primer is a carrier for the active stuff.

But, my opinion is not based on experience with Loctite.
 

Q-Dog

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Yes, you should use the primer if you want these to be permanent. Loctite red can only be removed by applying heat, so if you damage a stud you may lose the entire battery. It also takes 24 hours to cure.
 

fafrd

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Yes, you should use the primer if you want these to be permanent. Loctite red can only be removed by applying heat, so if you damage a stud you may lose the entire battery. It also takes 24 hours to cure.

I’m far, far more worried about damaging a soft aluminum terminal than I am about damaging a hard stainless steel stud.

You need to damage your own terminal firsthand to have an idea of what I mean.

The 24 hours is not an issue but if the result will only be ‘permanent’ if I use primer, just one more thing to order and wait for...
 

upnorthandpersonal

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From the Loctite datasheet: "A primer is needed if two inactive metals are used". From their website: "Active metals include iron, plain steel, copper, brass, bronze, nickel, manganese, Monel and Kovar". Inactive metals: "titanium, stainless steel, galvanized steel, zinc, pure aluminium, cadmium, magnesium, natural or chemical black oxide, magnetite steel, Iconel or any of your precious metals such as silver or gold."

So, considering you're using stainless steel + aluminium, you need a primer.

Sources:
1) https://dm.henkel-dam.com/is/conten...-Red-271-Carded-Tube-0.20-fl-oz-2018-04-09pdf
2) https://www.henkel-adhesives.com/fi...activator-with-your-loctite-threadlocker.html
 

Q-Dog

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Accidents happen. Drop something across the terminals and the shorting can damage the threads on the stud to the point it can't be used even though the cell may survive. Then you have to try to repair the stud.

I would use one of the lesser formulas of loctite that don't need heat to remove if I could be convinced it was necessary. At least there is a chance of getting the stud out and saving the cell if the need arises.
 

fafrd

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Accidents happen. Drop something across the terminals and the shorting can damage the threads on the stud to the point it can't be used even though the cell may survive. Then you have to try to repair the stud.

I would use one of the lesser formulas of loctite that don't need heat to remove if I could be convinced it was necessary. At least there is a chance of getting the stud out and saving the cell if the need arises.

Oh, it’s easy to remove the stud - you’ll just remove the aluminum threads with it. Apply enough torque from above and the stud will lift right out leaving a nice shiny flat-walled hole behind (ask me how I know).

And then you can tap in an M6 Helicoil to start the process all over again...
 

fafrd

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From the Loctite datasheet: "A primer is needed if two inactive metals are used". From their website: "Active metals include iron, plain steel, copper, brass, bronze, nickel, manganese, Monel and Kovar". Inactive metals: "titanium, stainless steel, galvanized steel, zinc, pure aluminium, cadmium, magnesium, natural or chemical black oxide, magnetite steel, Iconel or any of your precious metals such as silver or gold."

So, considering you're using stainless steel + aluminium, you need a primer.

Sources:
1) https://dm.henkel-dam.com/is/conten...-Red-271-Carded-Tube-0.20-fl-oz-2018-04-09pdf
2) https://www.henkel-adhesives.com/fi...activator-with-your-loctite-threadlocker.html

Yeah, that’s what I read and what caused me enough concern to post the question.

Loctite cures when there is no air and it is on the presence of metal molecules. The ‘inactive metals’ don’t contribute much of any metal molecules so curing either doesn’t happen or is exceedingly slow.

The primers do something to the surface of these ‘inactive’ metals to make them much better sources of metal molecules.

Seems necessary but if many here have gotten a good string cure without it and if the only real impact in our actual application is a longer curing time, maybe not worth the trouble.

Also, there are two types of primer, spray-on and bottle with applicator so if anyone has any experience with these primers, I’d appreciate advice on which is better (for this specific application of SS grubscrew in Al terminal).
 

fafrd

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I think 271 is superseded by 263 so they don't promote it anymore.

Ouch, so my local hardware store sold me obsolete product! If I’d purchased it through AliExpress at a steep discount, I’d be understanding but this was the local Ace at full retail price.

Good thing I kept the receipt.
 

upnorthandpersonal

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It's not 'obsolete' as far as I know. It has certain properties (like needing a primer) and it will still be available (as far as I know, it's still produced).
It's just that 263 is easier since it doesn't need a primer and covers the same use cases that 271 does.
 
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