Handy metric bolt torque chart

I see questions about torque specs for various projects so I thought I'd post this chart. It's from Yamaha Motor Corp. and sets out general torque specs through M12 - I wish it went higher, but this ought to get you pretty close if you're doing a job without any specs. I like that it gives a way to measure the fastener by the bolt head and the thread diameter to determine which spec to use. Hope it helps.

 

Thanks for posting, it is helpful.

 

I would be cautious about general torque specs. There are lots of variables besides just the size of the bolts that can affect the torque spec.

• Coarse or fine threads
• The grade of the fastener
• Dry or lubricated
• Conical, spherical, flanged, etc (in the case of lug bolts)
• Material being threaded into (steel into aluminum vs. steel into steel, etc,)

There are more…

I think it’s best to know the specification for the specific fastener and application.

 

As obviously stated in the post, these are good GENERAL torque specs that will get you there. If you read the chart, which you didn't, it's for ISO thread pitch with clean dry threads. If you want to get into whether an M8 needs 13.3 vs. 13.6 with assembly lube, you should contact Yamaha.

Do you have any data on the differences in torque specs for all the variables you posted that can help us out?

 

I like data, it’s usually useful. Would this data usurp the FSM? No, of course not. I think the OP was providing interesting data, nothing more, nothing less.

Practically speaking, in the field, I don’t carry a torque wrench. On the trail good and tight is good enough. I’ll use factory specs when I get home

I like Thai food too!

Cheers!
Mike

 

For fabrication, when using common rated fasteners that conform to a standard, I use an iOS app called iEngineer.

Here are some screenshots. Notice that lubrication can affect the specified torque by 25%. The grade of the fastener can vary the torque requirement by almost 40%.



I would be careful about general torque specs.

 

More interesting data! Thank you Captain Spaulding.

I also appreciate Spaulding’s posts. I think he really is an African explorer

 

In my advancing years I’m more likely to be exploring a steak house with subdued lighting, wood-paneled walls, and red leather booths.

 

That’s good info about lubricated threads and reducing the torque by about 25%. Folks should remember that anti-seize compounds are also lubricants.

 

If you dig into this issue, it’s as deep a rabbit hole among engineers as anything we talk about on this board. (Of course engineers merely discuss, while we bicker. LOL) I’ve read that anti-seize compound is somewhat of it’s own animal and that the torque value for fasteners lubricated with it should only be reduced by 15%, but there’s not any clear consensus on that that I was able to find. Besides, it’s too hard to calculate 15% in my head. ;-)