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Look on an all aluminum engine, lots of torque specs beyond 15 ft lbs on aluminum threaded holes.

I’m not saying galvanic corrosion isn’t a concern for many fasteners, but a zinc plated fastener in an aluminum internal thread is not a big corrosion concern. Especially in a dry, fairly well sealed application like a spark plug. It’s actually better from a galvanic potential standpoint than a zinc fastener in a steel internally threaded hole.
Not much, like I stated before. I didn't say none. I said few. I have many dirt bikes and cars all with shop manuals. Aluminum without a backing nut does not hold a lot of torque. It would have to be a bigger bolt with thick threads to torque more.
 

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Not much, like I stated before. I didn't say none. I said few. I have many dirt bikes and cars all with shop manuals. Aluminum without a backing nut does not hold a lot of torque. It would have to be a bigger bolt with thick threads to torque more.
Sorry, but you’re wrong here. It’s all down to shear area of the threaded hole and shear strength of the material. I can make a threaded hole in aluminum hold just as much torque/clamp force as a nut. And coarse threads don’t make an internally threaded hole appreciably stronger.

There’s nothing wrong with threaded holes in aluminum when designed correctly.
 

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Sorry, but you’re wrong here. It’s all down to shear area of the threaded hole and shear strength of the material. I can make a threaded hole in aluminum hold just as much torque/clamp force as a nut. And coarse threads don’t make an internally threaded hole appreciably stronger.

There’s nothing wrong with threaded holes in aluminum when designed correctly.
You keep proving my point, and you don't even know it. Show me your shop manuals. How about this....have you ever heard how often the e135 bolts strip when removed? If you don't believe me, go ahead and torque down that spark plug as much as you want. It is not my job to be the torque police anyway. Just don't come crying when you f it up.
 

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You keep proving my point, and you don't even know it. Show me your shop manuals. How about this....have you ever heard how often the e135 bolts strip when removed? If you don't believe me, go ahead and torque down that spark plug as much as you want. It is not my job to be the torque police anyway. Just don't come crying when you f it up.
I have a PE in this stuff (mechanical systems and materials), and it’s what I do in my day job with lots of different grades of aluminums and really fancy bolts. It really is as simple as I said before at the core of the calculation on sizing the joint.

Plenty of 60+ ft lb bolts in a 2GR-FE block if you want to look at a BGB for proof of the engineering.
 

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I have a PE in this stuff (mechanical systems and materials), and it’s what I do in my day job with lots of different grades of aluminums and really fancy bolts. It really is as simple as I said before at the core of the calculation on sizing the joint.

Plenty of 60+ ft lb bolts in a 2GR-FE block if you want to look at a BGB for proof of the engineering.
So, what is the torque for a spark plug?
 

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NGK’s recommendations look good. And on a dry fastener, you’ll get about +/- 30% clamp force on that joint with the same torque input. Which is a crazy spread, but it’s all baked into how bolted joints are designed.
Actually, I don't want to fight. I like everyone here. I just wanted to make a point that don't be surprised if torque specs are really low for aluminum. It is really common and for spark plugs it makes good sense. Also, oil filters...don't torque those down too hard, Peace.
 

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Actually, I don't want to fight. I like everyone here. I just wanted to make a point that don't be surprised if torque specs are really low for aluminum. It is really common and for spark plugs it makes good sense. Also, oil filters...don't torque those down too hard, Peace.
BTW, don't ever throw your resume down without knowing who you are talking to. I have a BS in Chemical Engineering and Computer Science. I spent 5 years working for a Radiographic physics department. I know the coefficient of friction of more materials than you have ever looked at. It is just BS to start smack talking with people you don't know. Peace.
 

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BTW, don't ever throw your resume down without knowing who you are talking to. I have a BS in Chemical Engineering and Computer Science. I spent 5 years working for a Radiographic physics department. I know the coefficient of friction of more materials than you have ever looked at. It is just BS to start smack talking with people you don't know. Peace.
Not sure why you’re so upset, but it’s not just Coulomb friction that influences this preload scatter.

Im not smack talking, but you’re a Chemical Eng telling a Mechanical Eng that specializes in this area that he’s wrong, as well as the spark plug Mfg’s recommendation is also wrong. You haven’t really provided any supporting info to corroborate some pretty outlandish claims like an aluminum internal thread can’t take more than 15 ft-lbs.

Bolted joints are deceptively complex at the detailed level, so I’d caution anybody deviating from Mfg recommendations without a lot of data and understanding to support that.
 

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I also want to get **** on my shoes!!!

Someone said earlier that they don't calculate the "added" torque for lubed threads

I just want to clear the mud, when you lube threads, you actually need less torque to achieve the same clamp load. So don't add oil AND reef on your wrench, you'll be upset lol

something like 60% of a torque value is just overcoming friction. And a lowly 1/4-20 alloy screw can provide nearly 20ksi of clamping force when torqued to 80% of it yield

oh and the 2-3 threads closest to the load surface (be it the nut or the cylinder head) hold most of the load too

that's all the **** I have to put on my shoes about threaded fasteners. I tend to avoid hardware and weld things together. Takes time and money to drill holes and add bolts 😂
 

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Not sure why you’re so upset, but it’s not just Coulomb friction that influences this preload scatter.

Im not smack talking, but you’re a Chemical Eng telling a Mechanical Eng that specializes in this area that he’s wrong, as well as the spark plug Mfg’s recommendation is also wrong. You haven’t really provided any supporting info to corroborate some pretty outlandish claims like an aluminum internal thread can’t take more than 15 ft-lbs.

Bolted joints are deceptively complex at the detailed level, so I’d caution anybody deviating from Mfg recommendations without a lot of data and understanding to support that.
You do realize all Engineers are a minor in math and all engineers have to take INDE (Industrial Engineering). I just happen to have taken the metallurgy part as well. I am not mad btw. I like a spirited discussion. I was just teaching a lesson to be careful about throwing resumes around. You never know who you are talking to. Have fun. Nothing on a forum should ever get anyone worked up. Let's just get back to constructive MR2 talk.
 

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You do realize all Engineers are a minor in math and all engineers have to take INDE (Industrial Engineering). I just happen to have taken the metallurgy part as well. I am not mad btw. I like a spirited discussion. I was just teaching a lesson to be careful about throwing resumes around. You never know who you are talking to. Have fun. Nothing on a forum should ever get anyone worked up. Let's just get back to constructive MR2 talk.
You keep saying you’re teaching me a lesson, but you don’t even learn the basics of how a bolted joint works in those classes or that entire ciriculum. It’s taught in machine design theory class, which is an end of Mech Eng ciriculum class. And even that is such a basic understanding of how they operate that it’s insufficient for actually making bolted joints that work.

So please stop acting like you’re treating the guy who engineered hundreds of bolted joints in aluminum this past week to a lesson in humility.

If you’d like to learn more on the topic to speak from knowledge and not conjecture, this is a good basic resource: NASA-TM-106943 - Abbott Aerospace Canada Ltd
 

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You keep saying you’re teaching me a lesson, but you don’t even learn the basics of how a bolted joint works in those classes or that entire ciriculum. It’s taught in machine design theory class, which is an end of Mech Eng ciriculum class. And even that is such a basic understanding of how they operate that it’s insufficient for actually making bolted joints that work.

So please stop acting like you’re treating the guy who engineered hundreds of bolted joints in aluminum this past week to a lesson in humility.

If you’d like to learn more on the topic to speak from knowledge and not conjecture, this is a good basic resource: NASA-TM-106943 - Abbott Aerospace Canada Ltd
You know what? I am tired of you. I tried to be nice. You are nasty. Go **** a duck. I have done way more than you know.
 

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You know what? I am tired of you. I tried to be nice. You are nasty. Go **** a duck. I have done way more than you know.
You know, it’s ok to admit you’re not an expert in something you have just cursory knowledge on. Apparently that’s beyond you.

I’ll be sure to let NGK’s and Toyota’s mechanical engineers know that some chemical engineer on an MR2 forum doesn’t know how a bolted joint works, but he’s sure they’re wrong in their official recommendations.:rolleyes:
 

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You know, it’s ok to admit you’re not an expert in something you have just cursory knowledge on. Apparently that’s beyond you.

I’ll be sure to let NGK’s and Toyota’s mechanical engineers know that some chemical engineer on an MR2 forum doesn’t know how a bolted joint works, but he’s sure they’re wrong in their official recommendations.:rolleyes:
All good. Love you. Just playing.
 

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Lol this thread.

I'm an Electrical Engineer. Hand tight + 1/4 to 1/3 turn is what I do lol. Never had an issue over the years with countless spark plugs.

Common sense and good judgment when tightening anything will get the job done 99% of the time. Most engineers can't wrap their heads around that . . .

The only time I break out a torque wrench on my own stuff is for Critical Safety Items like flywheel bolts, axle nuts, etc.

Sent from my SM-G973U using Tapatalk
 

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Discussion Starter · #37 ·
Geez...I just posted a simple question on spark plug torque and it went south pretty quickly. The last time I started a long thread was when I posted a YouTube that had a series by a mechanic who was rebuilding a MR2. I didn't realize the person was transgendered (not that that should have mattered) and that thread went off the rails and had to be pulled.

I better stop posting! 😬
 

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Nah, don't stop posting. Despite the friction here, there's definitely some useful info in this thread and everyone seems to have calmed down too. I would call this a 'spirited' thread, the same type of driving I'm going to do this weekend w/ my SW20.
 

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Discussion Starter · #39 ·
Nah, don't stop posting. Despite the friction here, there's definitely some useful info in this thread and everyone seems to have calmed down too. I would call this a 'spirited' thread, the same type of driving I'm going to do this weekend w/ my SW20.
I hope to do some “spirited” driving this weekend!
 

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I hope to do some “spirited” driving this weekend!
I hope to do some “spirited” driving this weekend!
Nobody stop posting! Please. That is not the intent. It might be the politics lately that get me worked up. :) I was saying few things: 1. NGK is the only plug that puts a coating on their threads for some reason. 2. Metallurgy is important and you can mess up your nice aluminum head or valve cover that don't take precautions. 3. Anti-seize is really kinda anti-corrosion and you should learn about it. Everyone should Don't put a stainless steal dress kit on your aluminum valve cover without understanding. 4. Don't assume who you are talking to. We all have resumes that are well deserved. I have been alive for 54 years and building cars since 14 or less. I love it and want to keep loving it through MR2OC. ;)
 
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