Buy a torque wrench......a good one...

[Trailbus]

A lot of wrenches have a conversion chart right on the handle for you metric guys. Or, you could use the number in the
parentheses next to the metric one in the manual.

 

[Trailbus]

I am always wondering whether I can easily use one torque wrench to test the others assuming the range overlaps. I have a craftsman that I use for years on my bikes, and I believe it is reliable, and recently I got a couple of used snap-ons. To test the snap-ons, I put a bolt on the vise, and tighten it to a number with the craftsman, and then check the new snap-on for the same torque. I know it is not very scientific, do you think the method effective at all?

You could, but it would really only show you it is working, not really the accuracy. It would be better to use a dial indicating or beam style wrench as the standard & watch to see where it clicks. Really a mute point though, I've seen wrenches be good at the lower 60% of the scale then go off in oblivian at the top end. I used to work part time at a cal lab in Boise (Boise calibration service over by costco) & they only charged like $35 to get a typical wrench calibrated. If it was uncalibratable (bad), the owner usually dropps the price way down just to keep you coming back.

In addition, I am under impression that when a click-type torque wrench lost its precision, it tends to always over-tighten a fastener. Is it correct or it can go wrong both ways?

Not always tighter, as the spring wears down, it gets looser & reduces the force on the pivot point which in turn reduces the required torqu to make it "break". The pivot point is a small block of steel (~1/4 x 1/4 x 3/8 for the medium size wrenches) that cocks to the side when the sideways tension excedes the force it has between the 2 flat surfaces. Dirt, wear, & lack of grease are 3 of the most common things that cause a wrench to give erronious values.

Inportant!!! If you take the wrench apart don't expect it to be the correct torque value when you put it back together.

 

[wxm]

Inportant!!! If you take the wrench apart don't expect it to be the correct torque value when you put it back together.

I was quite tempting, guess I am not going to now... Thanks Trailbus!

 

[fjfar80]

Here is a good thread I came across on torque wrenches when I was doing some research. I am not sure about the information (accuracy) but, it seemed pretty helpful. It looks like a Mustang board...but the information was useful.

- Mark

 

[xingji]

I have yet to receive my FSM. But I'd like to go pick out my torque wrenches now. Just curious what range should I be looking for.

Thanks

 

[RavenTai]

I have yet to receive my FSM. But I'd like to go pick out my torque wrenches now. Just curious what range should I be looking for.

Thanks

The lightest I have found is spark plugs at 14 Foot pounds, the heaviest is just over 300 'lb for the crank bolt. You need a little wider as torque wrenches are most accurate through the middle of their ranges, less so at the extremes.


You are not going to find that kind of range in one torque wrench nor would you want it, first one I would get a medium sized one that would cover at least 30 to 150 foot pounds, the majority of the important fasteners are in this range. Later you can get a small one for light weights bearings spark plugs etc. get a big-un if you ever need it.

 

[xingji]

awesome, I picked up a 10-80 and a 20-150 already, good to know that I didnt waste any money lol

 

[Trollhole]

I'll admit I've got a crappy craftsman wrench ft-lbs and a bar style in-lbs wrench.

I do have a habbit of buzzing things on with the air ratchet and being done with it. But when it came to steering or my engine I went by the book. Exactly. It was a pain going through the fsm. Id even torque everything 10 lbs lower than what it called for and then come back and finish it off.

Sometimes it's just not worth screwing it up. JimC has a good thread in the 40 section about impropper bolts and torques.

I'm planning on getting a cobalt wrench.

 

[Gumby]

Anything under 20 lbs/ft I do with an inch pound wrench. I just don't trust the big ones much at low values.

 

[e9999]

so, which ones are more accurate and/or likely to maintain accuracy: beam-flexing bar types or click types?
(not talking convenience here of course)

 

[WarDamnEagle]

I wouldn't consider myself an expert on torque wrenches but I will give you my opinion anyway....

If you think about it, there are two "accuracy" issues, the actual ability of the torque wrench to accurately produce an indicated torque and the users ability to apply that torque accurately. I think with a click type, if you have a high quality torque wrench then you will get somewhere within 3 or 4% of the dialed-in torque and, of course, applying that torque is quite an accurate affair as it clicks and gives when it's time to stop pulling.

The bar type might be more reproducable over time but how accurately can the user apply that torque? Probably depends on the user.

The dial indicating type strike me as very accurate (they are typically rated at 2% vs. 4% for the click type and can even be bought at 1% accuracy). Also, it seems to me that the dial type have much more needle movement over the span of the wrench than the bar type. That indicates to me that the dial type would be more accurate in the application of a given torque than the bar type. Of course it's still more prone to user error than the click type.

I lean toward the click type for larger torques (say 15 ft-lb and up) and the dial indicating type for in-lb ranges.

I should add that I use a torque wrench about 4 or 5 times per year at most so, again, I'm no expert by any stretch of the imagination.

 

[e9999]

accuracy and repeatability and resolution and readability are different issues of course.

I'm tempted to say that the beam type should be more repeatable, and probably more accurate. The resolution probably not great at least with the direct readout and needle type, just too small a scale. But using them upside down sideways under the truck would likely be trouble for usability...

 

[cool breeze]

So how would I go about having my old craftsman tw calibrated...sears?

 

[Trailbus]

Time to do some Googlin'. All kinds of places in S.A. Call around, prices can vary by quite a bit.

 

[e9999]

yes, but is it likely that having a pro shop calibrate an old one will cost less than a new reasonably-priced one?

 

[cool breeze]

FYI: My local calibrator quoted $48 for tw's up to 250 ft/lbs. Had to call 5 different sears numbers before parts dept said craftsman does not offer this service. I really just want to know if its working properly, dan said the snap-on guy has this...how do i find this dude?
Snap-on, Snap-on, Snap-on!

 

[CruisinGA]

Snap-on guy is not going to want to test anything that is not Snap-On, unless he gets to tell you to buy a snap on one when yours is out of whack.

They don't typically want to provide much service to anyone not on their account list.

If you just want to see if yours is accurate on the cheap, get a known accurate pull scale and a lever of measured length, hook it up to your torque wrench and do a little unit conversion and voila, you are testing your own torque wrench. (ft-lbs = length of lever from pivot to scale, lbs= reading on scale, multiply the two)

Personally, I would pay the $50 if I had a good wrench worth calibrating.