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Torque wrench
- Thread starter vvMINOvv
- Start date
I agree to an extent but IMO a torque wrench is still a required tool for the weekend wrencher who can't justify or afford a high end piece. Even if the tool isn't accurate to within 2% I'd rather torque within ballpark than guesstimate it.
I thought it looked pretty simple. One of those "why didn't I think of that?" things. Am I missing something?
If a torque wrench can consistently deliver 98% accuracy within 80% of its torque range then, there's no problem. That's what I'd expect from a micrometer style snap-on torque wrench.
The ones you get for $50 will be 96% accurate but only within the very middle 40-50% of the torque range, and it'll only do that a hand full of times before it starts to go wrong, leaving you either wildy over-torqued or under torqued. And don't think you can get away with not calibrating them yearly just because you don't use them that often; torque wrenches are like oil. Even if you don't use it, it's still a good idea to get it calibrated regularly.... especially if its a cheap unit prone to break to begin with.
$150 is not an insane amount to spend on a high-quality 3/8 drive torque wrench that you'll have for the rest of your life.
http://www.ebay.com/itm/SNAP-ON-TOO..._Automotive_Tools&hash=item35c351df45&vxp=mtr
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IMO it really depends on what you plan to use it for, either basic maintenance or engine building...Personally I own a Snap-on that I paid about $400 for, but I use it to build engines, where accurate torque is important...Like crankcases, cylinder heads, connecting rod bolts, etc....
I didn't know the accuracy can be inconsistent throughout the torque range, good to know. I basically agree with all of this except I was coming from the perspective that $150 is considered a "cheap" torque wrench vs the $400+ torque wrenches mentioned earlier.
Do you have the dial type wrench? Those are awesome. I'd like to own one but can't justify the expense. I've only built one motor in my lifetime and probably won't do it again.
Yep, the +/- 2% accuracy they say on the box only applies to about 60-70% of the middle of the torque range. The accuracy gets worse the further out you get.
On low quality stuff, the accuracy suffers alot (up to 10 ft/lbs on my ****** $20 one straight out of the box) but even the high dollar snapon units suffer a bit... so you really need the right size torque wrench for various jobs. Don't use a 20-200 ft/lbs torqure wrench to tighten something to 20 ft/lbs for example.
I'd recommend most people get a 3/8" drive as it covers the greatest number of torque specs you'd find on a typical bike or car.
I checked the calibration cert that came with mine which more or less verifies this. The variance at different torque values is different. Thanks for the info!
IMO a good quality wrench is whats important. When torqing engine bolts its most important to have consistancy rather than hitting the "exact" number. For example unless you are using NEW bolts there is a certain amount of stretch in the bolt as well as the thread so the EXACT spec laid out in your manual is rather inaccurate for the task at hand. Now I am not saying that you shouldnt torque down head bolts to the spec as best as you can but dont for a minute think that everytime an engine comes apart is going back exactly as it did from the factory. Its far more important to use the correct pattern and bring them all down to the "same" spec even if its off by a percent or two.
Have you ever seen the inside of an engine assembly plant? Hell the workers use pneumatic tools that I am pretty sure dont have as tight a tolerance as 99% of decent torque wrenches available.
Have you ever seen the inside of an engine assembly plant? Hell the workers use pneumatic tools that I am pretty sure dont have as tight a tolerance as 99% of decent torque wrenches available.
I see plenty of auto industry manufacturing. At an OEM level, every critical fastener is tightened down using an electronically-controlled torque gun that essentially uses a servo motor in torque mode to tighten the fastener down, and the controls for the workcell have various levels of idiot-proofing to ensure that all of the fasteners have been installed and torqued properly. The completed assemblies are usually date-coded after it passes a validation check of some sort (depending on the type of assembly). Once it becomes possible to track which vehicle the assembly will be destined for, measured tightening torques and validation test results are logged by engine number or VIN, and they will track which date codes are on the subassembly parts that go into that engine number and VIN so that if something happens in the future, they can track it back.
This is not to say that screw-ups are impossible. BMW had an issue with the S1000R in which certain con-rod fasteners were not properly torqued. But they identified a very specific VIN range that was affected - because they knew that it potentially affected all units between when the calibration error on the specific torque gun was discovered, back to the previous time that its calibration was logged as being correct. Only way that can be done, is to track everything by engine number or VIN.
This is how the auto industry works nowadays. It has to be like this. If there's ever a problem that causes a recall, they need to know exactly which vehicles were affected.
The average mechanic doesn't have a fancy servo-operated torque gun like that ... but the average mechanic doesn't need to put a whole car together with only 10 or 15 man-hours of labour TOTAL ...
The Atlas-Copco eletro-pnuematic assembly guns that are common in assembly plants also have an electronic cutout so when the desired torque is reached the gun shuts down and there is no wrist snap, nobody gets repetitive motion injuries. But thats in the thousands of dollars per tool world.
I tried my princess auto 3/8 and 1/2" against my mechanic nieghbors snapon, I was 4% out at 45ftlbs on the 3/8 , and 8% out on the 1/2" at 60ft lbs. The certificate that came with mine was out by 3% using the snapon as a test. Its ok according to my nieghbor for non critical work like aluminum rims or water pump bolts.
He did make sense when he asked would you potentially wreck a $5,000. dollar engine over a $35 dollar tool?
I tried my princess auto 3/8 and 1/2" against my mechanic nieghbors snapon, I was 4% out at 45ftlbs on the 3/8 , and 8% out on the 1/2" at 60ft lbs. The certificate that came with mine was out by 3% using the snapon as a test. Its ok according to my nieghbor for non critical work like aluminum rims or water pump bolts.
He did make sense when he asked would you potentially wreck a $5,000. dollar engine over a $35 dollar tool?
hedgehog23
Member
Knowing how to use one correctly is just as important as a quality tool. Sounds kinda dumb but take it from me most people dont.
Until you use one on a test rig/ torque stand , the idea of improper use sounds dumb. Warm up, proper even pressure pulls , and and let off are keys to doing it right.
On avg. most people over torque fasteners by 30% WITH a torque wrench. (from what i have seen in person, not an industry avg)
Until you use one on a test rig/ torque stand , the idea of improper use sounds dumb. Warm up, proper even pressure pulls , and and let off are keys to doing it right.
On avg. most people over torque fasteners by 30% WITH a torque wrench. (from what i have seen in person, not an industry avg)
You only need a torque wrench with that doesn't go over +/- 4% accuracy to work on aircraft (I work on aircraft). So technically my Carquest one can do the job, it was at 4% exactly. My Mastercraft one was off by 8% after 3 years when using the maximum setting.
What hedgehog23 said is accurate. I saw the guys testing my tools and you can easily over-torque by 20% or more.
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