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      03-13-2013, 04:13 PM   #1
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Any engineers here? Need help with bolt torque

Anybody studying engineering?

What is the maximum torque for a M8x25 (10.9) bolt into 6060 aluminium please (thread depth 15mm)? Or am I better off using a stud and nut? I need 34 Nm and AFAIK Al will only hold 25 Nm on a good day...

This is for the M3 strut brace...

Many thanks.
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      03-13-2013, 06:17 PM   #2
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You need to talk to Shah
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      03-13-2013, 07:12 PM   #3
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M8 by what? whats the thread pitch? And are you sure it is a 6060 aluminum? I ask bc I can only seem to find information on T4-2024 aluminum bolts.

If it is 2024 aluminum and it is M8x1.25 it would approx be 10 NM. Don't quote me on that my conversions could be wrong.

6060 should be stronger so maybe it might be ok.

I would stray away from using aluminum studs or bolts. They yield way to easily. A zinc plated steel class 12.9 will get the job done.
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      03-13-2013, 07:54 PM   #4
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for a strut brace? just eyeball it, it's not a spaceship
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      03-13-2013, 08:13 PM   #5
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Doesn't the strut brace call for 16-24ft.-lbs of torque or something like that? That's like 21Nm - 32Nm.
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      03-13-2013, 09:16 PM   #6
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Quote:
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You need to talk to Shah
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and he's out of work so he has time
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      03-14-2013, 12:37 AM   #7
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bad thread, good responses
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      03-14-2013, 06:29 AM   #8
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Thank you

I'll try get hold of Shah

I'm not going to eyeball it. TIS calls for 34Nm.

The bolts are carbon steel zinc plated M8 and they're going into aluminium of the brace, which has threads in it.

I can also use studs and nuts, but that may be too high to fit. Will using studs help any in regards to torque?
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      03-14-2013, 07:10 AM   #9
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Quote:
Originally Posted by Bakeme521 View Post
M8 by what? whats the thread pitch? And are you sure it is a 6060 aluminum? I ask bc I can only seem to find information on T4-2024 aluminum bolts.

If it is 2024 aluminum and it is M8x1.25 it would approx be 10 NM. Don't quote me on that my conversions could be wrong.

6060 should be stronger so maybe it might be ok.

I would stray away from using aluminum studs or bolts. They yield way to easily. A zinc plated steel class 12.9 will get the job done.
The female end is AL, not the actual bolt...

Are you using any locktight never-seize??
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      03-14-2013, 09:05 AM   #10
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strut brace...?
Just add some locktight and give it a good turn.
You don't have to be exact. Just make it tight.
It's not seeing any tensile forces so no worries.
25 ~ 18ftlbs...so just give it a nice tug. Dont' worry and don't over think it.
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      03-14-2013, 09:43 AM   #11
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Studs and bolts are the same in regards to the torque...

Here's a quick lesson on fasteners. Think of a bolt (or stud) as a spring.. Essentially what you are doing when you tighten a bolt is you are stretching it, which puts pressure on the joint. Theoretically, you want to tighten (or stretch) the fastener as much as you possibly can within the elastic limit of the material..

The *best* way to ensure a fastener is correctly tightened (stretched) would be to measure the length before and after (or the change in length), one can easily calculate the length that the bolt should be in a perfect world. This is pretty impractical to be able to do, especially when you're threading the fastener into a tapped hole.. Since it's difficult to measure this change in length, you can also determine the torque required at the bolt head to attain this change in length, however you are making some assumptions that aren't ideal, in that it's impossible to generalize the friction in the threads and whatnot...

With all that said, I agree that the torque in this application really isn't that important. If you're concerned about it coming apart, use some nord-lock washers and it will never come apart!
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      03-14-2013, 10:42 AM   #12
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Quote:
Originally Posted by happos2 View Post
The female end is AL, not the actual bolt...

Are you using any locktight never-seize??
Yes, exactly, the female end is Al, the bolt is carbon steel grade 10.9, as I said before...

Nord Lock - looks interesting, but not this time, I need the torque - I'm not going to doubt BMW engineers (yes, the ones that say 20k oil changes are fine, I know....)

So, if there is no difference in torque between a stud and a bolt, then how come Al is supposed to only hold ~25 Nm, but BMW TIS calls for 34 Nm? I don't understand...

Shah does not take PMs, so if someone can contact him and direct him here, I'd be grateful...
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      03-14-2013, 11:12 AM   #13
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Quote:
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Shah does not take PMs, so if someone can contact him and direct him here, I'd be grateful...
Shah posted above.
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      03-14-2013, 12:19 PM   #14
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Quote:
Originally Posted by shah269 View Post
Dont' worry and don't over think it.
the Shah has spoken

http://f10.5post.com/forums/showthread.php?t=807217

don't indulge him, OP has a habit of making a mountain out of a molehill
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      03-14-2013, 12:46 PM   #15
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well....I was going to suggest after he did what he needed to do to spray a bit of clear on top just to keep it looking sexy
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      03-14-2013, 01:27 PM   #16
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Quote:
Originally Posted by grimlock View Post
the Shah has spoken

http://f10.5post.com/forums/showthread.php?t=807217

don't indulge him, OP has a habit of making a mountain out of a molehill
Yes, I do, I am a perfectionist...

But then again, why not? Especially in this case... if 25 Nm would do, wouldn't BMW say tighten it down to 25 Nm? They did the research and came to 34 as the number... and I have nor the knowledge nor the time to dispute their reasoning and research.

What I can do however, is find out how to tighten the bolts to 34 Nm, which is what I'm trying here...

Or TIS could be wrong, because the values on Billswebspace are from 2008... maybe they changed it? Anybody have access to BMW TIS?
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      03-14-2013, 01:41 PM   #17
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how to tighten the bolts to 34 Nm?
https://www.google.com/shopping/prod...d=0CI4BEPMCMAE
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      03-14-2013, 01:56 PM   #18
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Quote:
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I have a wrench... I meant how to tighten them to 34 Nm without striping the threads in the aluminium part...
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      03-14-2013, 02:02 PM   #19
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Ok hold on a second, is the nut aluminum or is the bolt aluminum.
don’t want to mess with your head but mating two dissimilar metals like that is a bad thing.
it should be aluminum to aluminum or steel to steel
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      03-14-2013, 02:20 PM   #20
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true
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      03-14-2013, 02:53 PM   #21
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Here is the brace:

http://realoem.com/bmw/showparts.do?...=51&fg=75&hl=1

I'm talking about parts 1,4 and 8.
1 = aluminium
4 = stud steel
8 = nut, steel

Instead of parts 4 and 8 due to space constraints I want to use a steel bolt.
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      03-14-2013, 04:47 PM   #22
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so it's steel on steel....just give it a good turn till it's tight.
The part is not in tension so you are 1000000% ok
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