Drive chain maintenance

[L.B.S.]

...so I'm taking this as you guys don't Vulcan mind meld with your fasteners before tightening?

 

[Therapy]

In my line of professional work, certain critical tasks require torque wrench use - no if, and, but, or guessing. It's just as bad to over tighten as to under tighten. (Given a chance, my guess is more people will probably over torque than under - good 'n tight, right?). I figure the safety aspect of my motorcycle is just as important as the machines I service, so all critical fasteners like brake calipers, axle nuts, and engine bolts WILL see a torque wrench. I treat it as mandatory, just like helmet use.

A warning to all with "calibrated" wrists: the NC700 cylinder head cover bolts require much less torque than you might think.

Actually I am more with you than not. Engine, for sure, plastic bling, not so much.

 

[MZ5]

When I pulled the front wheel off last Saturday, to give it to the shop who was going to change the tire for me, I had to pull the brake caliper, too (to get it back on without using naughty words or bashing the brake pads to bits). When I put the caliper back on, the mount bolts saw a torque wrench. The torque wrench they saw was the 1/2" drive one that I borrowed to remove & reinstall the front axle. They saw it near them, they cowered in fear, so I put it away and tightened them with the Honda end wrench in the bike's tool kit.

I'm funnin' with everybody, of course, though the story is completely true and accurate.

I'd have preferred to have used a torque wrench on them, but I didn't have one, and I'm not the slightest bit concerned about it. When I get home in a couple months, I might put a torque wrench across them for fun. If I use each of the torque wrenches I have that cover that range, I'll bet an ice cream cone that I get significantly different amounts of tension from each. ...at least that's what happened the last time I compared two of my torque wrenches...
;-)

 

[Therapy]

I have a question about those that have used wrenches a lot.

Torque values are for new un-lubricated bolts as far as I remember.
I remember reading that if a bolt is dirty it will put up more resistance but not really be that tight and that if a bolt is lubricated it will offer less and will be over-tightened. This is with the torque wrench reading the same reading for all three bolts.
It was a long article that was referenced in a marine related thread concerning repairing diesels.

Any experience with that idea?

Found this.
file:///C:/Users/Owner/Downloads/Torque+and+Torque+Wrenches.pdf
Practical Maintenance » Blog Archive » Tightening Methods for Threaded Fasteners

Makes me think only a Snap-on or equivalent will do. $$$?

 

[MZ5]

Torque is really not what you're trying to accomplish with a fastener like a bolt. What you're trying to do is achieve a certain amount of clamping force between the parts the bolt(s) hold together, and you get that by tightening them (the bolts). This puts some tension on the bolts in the process, and the amount of tension is far more important than the input torque applied to the bolt. Torque is just a proxy for clamping force, because it's much simpler to measure.

ASME standard is that torque specs assume clean, dry threads on both the bolt and the nut or part it threads into, unless stated otherwise. Too, the variability between applied torque vs. tension/clamping force is surprisingly variable. The amount of variability with anti-seize has been shown in at least one study to be much lower than with dry threads; on the order of only 10% as much variability.

If your torque spec calls for clean & dry threads, you must reduce applied torque for lubed threads, if you want to keep clamping force the same. What the threads are lubed with determines how much of an applied torque reduction is necessary to achieve the target 'squeeze.' Still, ~25% is a rule of thumb for lubed fasteners. 30% is closer to what I've read from industry when using anti-seize.

Spark plugs are a good case study on this issue, for a few reasons. Though it's become fashionable of late to have a torque spec for spark plugs, many of us recall that it's been standard practice for at least decades to specify that spark plugs should be tightened until they make contact with the head, and then tightened a certain fraction of a turn more. What fraction depends mainly on whether the application uses a crush washer or not.

Here are a couple of references on the topic:
http://www.henkelna.com/us/content_data/333994_LT6734.pdf
http://www.antiseize.com/pdf/torque_specifications.pdf

 

[maxwellian]

Yeah, I can attest to the dry threads varying wildly in torque. Bicycle spokes are easy to measure tension in, and the torque can really vary for a given tension.

And as far the torque specs for the NC, I think more than half of them are not for dry threads, but with thread locker or oil added.