Another bad news torque wrench story

[Stig / Major Tom]

Guy with a Honda scoot did a valve check. Valves were good, but snapped off a valve cover bolt during reassembly. Used a torque wrench properly set......but bolt snapped off before wrench ever 'clicked'. Another guy said same thing happened to him.
Very lucky. Could have stripped the head.
He's staring at his torque wrench, wondering what went wrong.

To each his own. ...but I never use a torque wrench on those bolts, spark plugs, CVT covers, drain plugs, or any small fasteners.
Just snug, with a smaller ratchet. I'm working on a scooter,  not a moon shot.

Stig

[ophelia]

Yes, little bolts need little torque wrenches to suit if one is used at all. Those valve cover bolts usually take a mere 8-15 ft-lbs. It's not much.

[stuo]

Yes, I don't trust those click torque wrenches, either. I use a 1/4" ratchet and place my twisting hand down the handle by the socket so I can't put too much force on the fastener. The only torque wrench I own, and trust, has a solid needle that points to the numbers on a scale as the wrench bends. It's over 50 years old, a Craftsman, foolproof, but almost never used. Trust your feel is my motto. Those exact torque numbers put out by the manufacturer are hooey, in my opinion.

[jeeves]

A quality torque wrench is not cheap, and every torque wrench should be calibrated after a period of use, but don't know anybody who does that.
Only use it on my motorcycle for bigger bolts.

[Forbes1964]

Some have their torque wrench set in FOOT pounds when in fact those small bolts call for torque in INCH pounds

[hypophthalmus]

I've learned the hard way that torque wrenches aren't foolproof. But the smaller torque wrenches are reliable for small fasteners.

I don't think it's as much a matter of the quality of the torque wrench as it is having a wrench that's appropriate for small fasteners.

I think learning how to go by feel is harder if you don't have a torque wrench. It still surprises me sometimes just how little the smaller bolts need to be torqued. And it still surprises me just how much the larger ones need to be.

Some small bolts I think are more worthwhile for safety to tighten to spec. My front sprocket for instance used two very small bolts that are awkward to tighten, and it's very important that they neither snap nor loosen. Front axle pinch bolts I think also qualify.

[hypophthalmus]

Regarding spark plugs, I happened upon one manufacturer's recommendation for tightening it by rotation. Apparent if you take the plug out, it requires much less rotation the second time. I did notice this seemed to be the case using a torque wrench.

http://www.globaldenso.com/en/products/aftermarket/plug/basic_knowledge/installation/index.html

[hypophthalmus]

I should clarify, when I said the smaller torque wrenches are reliable, I meant as reliable as the larger ones are for larger bolts.

Either way, some paranoia and good judgement are in order.

[Tromper]

I love my HF 3/8ths click wrench, but for lighter stuff, but it's not really that great below ~10 ft lb's, so  where I can fit it in. I use my old beam style craftsman one (old enough that it was made in the USA)
I've debated getting the 1/4 inch click wrench from them for the lighter stuff though since it's more compact & fits small spaces better than the beam style.

All that said there is no substitution for knowing what "tight" is from experience.  I did sheer a few bolts learning that.

[MJR]

Never had a problem but one should have in lb and ft lb torque wrenches. Another big problem is folks using ratchets too big for the job use 1/4, 3/8, and 1/2 for the right job, don't use a 3/8 ratchet on bolts with smaller than 13mm bolt head size.