TORQUE Coffee Talk

Questions keep popping up for me about torque, torquing etc.and such questions are always on the edge I being tool questions or procedure questions , so I put it here. 1. Does using a modest drive adaptor such as 1/4 to 3/8 affect the torque process and results... if so.. Higher or lower results than intended. 2. I hear that the middle 60% of a wrench range is where it is most accurate? True? 3. I know that oil on threads significantly affects torque unless accounted for by and directed by the engineers. But are the engineers know that some things such as oil filters and drain plugs WILL always be wet when they creat torque specs? 4. About rotating tires... Is this procedure (I have hand tools only) ok? Or where is it going wrong? A. With car on ground break nuts just loose with breaker bar and socket. B. Lift car, spin off nuts C. Rotate tires to new positions D. Start nuts onto threads a few turns by hand, then using my four way tire iron, spin them snug just to hold rim flat. E. Lower car slightly to put enough weight in tires that the cant spin freely. F. Use torque wrench set to half the final torque To then tighten nuts in star pattern jumping across from each other. G. Lower car fully, set torque wrench to total spec'd torque and do final tighten to spec. Again cossin over to opposite but each time thereby creating a star pattern. I ask because I specifically don't like the idea of spinning on the nuts by hand and then lowering full weight onto tires BEFORE doing ANY real tighten of any kind. It just seems like it would create a gap that then has to be pull against to 'correct' by torquing. Thus my steps E-F a pre torque of sorts....is that A good idea? 5. My Camry says that the transmission over flow tube (which is covered by an overflow plug at a higher torque but not of importance here) needs to be tightened to 7 inch pounds. Yes. 7 INCH pounds. Isn't that LESS than even finger tight? Where do I get a 6mm hex drive Allen socket and torque wrench that low of strengnth?! 6. In general is pre torquing I half torque a good thing before final torque. I am thinking of things besides rims such as oil pans etc. ?
 
Messages
524
Location
sc/fl
1. no 2. depends on the quality of the tool. 3. yes they take that variable into account 4. sounds fine 5. just snug it down and don't worry about it. 6. I personally believe in torqueing incrementally. Particularly on high torque items. just my $.02
 
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5,117
Location
Columbus,Nebraska
I'll let more experienced members answer most of your questions. See what Snap-On or Proto say about use of torque wrenches. Forget about something that requires seven inch pounds of torque. You won't use that torque wrench three times in your entire life. Manufacturers always specify torque values and tightening patterns. I had a lot of experience with industrial piping systems, and I saw large raised face flanges damaged because the proper tools and procedures were not followed even though the procedures were clearly spelled out on the work order. Always helps to inquire. Use of torque wrenches is the way to go. Regards
 
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1,048
Location
SE Wisconsin
1) My thoughts are that a drive adapter or extention will affect the torque applied, but only to the extent that the drive adapter or extention twists under torque (thus absorbing some of the force you're attempting to apply to the nut) - in other words, not much, probably not enough to matter. 2) I've heard the same thing, the middle of a torque wrench's range is the most accurate. I've never verified this, though, as neither of my two clicker-type torque wrenches have ever been standardized or checked for accuracy. 3) Good question. I don't know. 4) I follow a very similar procedure (just rotated my tires last night, in fact): a) Place jack under axle or frame (depending on vehicle) and lift about half (unscientific measurement) of the vehicle's weight off the tire. Then crack lug nuts loose. (I use my torque wrench set to about 1.5 times the application torque, that way I can verify they aren't grossly overtorqued. Yes I know I'm not supposed to crack lug nuts loose with a torque wrench, yes I know I can ruin it. No, I don't care if I mess up a $60 torque wrench, and no, I don't think it will mess it up anyway since I set it for about 1.5 times the applicaiton torque, the bolts crack loose before the wrench clicks. I've been doing it this way for a few years and my torque wrench still works to the precision I need it to, I don't care as much about accuracy as long as the precision is good. YMMV, don't try this at home, I am not responsible if you ruin your torque wrench). b) Jack wheel off the ground all the way, then run the lug nuts off with a cordless drill (SUPER TIME SAVER!) c) Rotate! d) Start lug nuts on by hand to ensure they catch the threads correctly, then run the lug nuts on all the way with cordless drill (super time saver!) set to a little over half its maximum torque setting (number 12 or 13 on mine), in a star pattern. Then, set cordless drill to its full torque setting (22 on mine), and snug them up, in a star pattern. e) Lower wheel onto ground just enough to touch pavement so the wheel will not spin. f) Snug lug nuts up to about half (unscientific measurement) of the final torque, in a star pattern. Then torque to full spec in a star pattern. g) Lower car fully, then re-check torque in a star pattern. 5) 7 inch pounds is crazy light, they probably just want to make sure nothing gets cracked/broken. 6) It is a good idea unless something else is specified. Similar procedures are sometimes required on cylinder heads and valve covers, but in those cases it may not be 'half', it may be something less or more.
 
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778
Location
Southeast Michigan
1) Not in the slightest. 2) It depends on the particular wrench and its calibration. Some will be good in the middle of their range, some will be good at one end or the other. Only way to know for sure is to have it calibrated, and for the price, you might as well just buy one with a cert already behind it. 3) It depends on the competency of the engineer, but you have to figure that for certain situations they know what they're doing. 4) I'd skip step F... a good hand tight connection isn't going to move under static load. 5) I'd bet good money that somewhere in Toyota's quality documentation it says that they don't have a threaded connection without a torque spec applied to it - that's why they put a number on there. Finger tight is fine. 6) If you're getting more than about a quarter turn of the torque wrench before it clicks when you go to final torque, you didn't have the fastener tight enough before hand. That's all I really have to say about the concept of pre-torquing.
 
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2,408
Location
CA
4)For your tire rotation, E-F, doesn't matter so much. Just get them, on torque to spec. You are better off spending those steps to move the car a bit, then retorquing after a short distance (just as it says what you do for spare tires, or the disclaimer when you get new tires at the tire shop) When breaking or spinning the lugs on or off you can use power tools is fine. If you do this, you're supposed to use a softer socket versus your hardalloy tooling socket. 5) for the 7inch pounds, use math to guestimate. Measure your tool's length to the fastener and attempt to apply the force at the other end. So like if your allen tool is 2inches long, press on the other end with what about what 3.5 lbs weighs. 6) The half-torque stuff is only required if it says so in the service manual for that procedure. Usually the torque is doing irreversable things like stretching something or crushing a part that is meant to be stretched or crushed. If the part is reusuable and not a 1-time use, then the half-torque stuff doesn't matter.
 
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Messages
8,859
Location
Texas
Originally Posted By: SumpChump
5. My Camry says that the transmission over flow tube (which is covered by an overflow plug at a higher torque but not of importance here) needs to be tightened to 7 inch pounds. Yes. 7 INCH pounds. Isn't that LESS than even finger tight?
Its more than finger tight. Its equivalent to pushing with ONE pound of force against the tip of a 7-inch long wrench. That's reasonably sung, not just "finger tight." Unless your fingers are a lot stronger than mine! Remember, "foot pound" and "inch pound" are very literal. How many inches (or feet) long is the lever, and how many pounds do you apply at the end of the lever? 10 foot-pounds is 10 pounds of force at the end of a 1-foot lever, OR 1 pound of force on a 10 foot lever, OR 5 pounds of force on a 2 foot lever. That will give you a pretty good feel for the actual forces involved.
 
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8,083
Location
MI
It's excellent to know the limitations of the tool. Many people think that because you are using a torque wrench, you automatically are getting very accurate results. That's just not true. Using a $400 tool incorrectly can be worse that doing it manually, or by feel. Finger tight and hand tight are useless measurements. Consider the difference between the results of a body builder vs. a 100 lb. weakling. Measuring fastener clamping force with torque (turning force) is very crude at best. Engineering forums agree that torque measurements can vary about +/- 30% due to many variables such as thread cleanliness, lube, design, flaws, etc.. Keep this in mind when worrying about a wrench being most accurate in the middle of its range. It may be most accurate there, but a calibrated wrench will still fall within its spec. (usually +/- 2 to 4 %) from 20% of full scale to full scale. The 30% figure above makes most of this concern a moot point. The wrench/fastener needs to be turning smoothly as you reach the final torque. You can't get the bolt up to 95 ft. lbs., stop, then restart to get up to 100 ft. lbs.. The binding or break away force will bugger up your final measurement. I don't know if any rules exist about wheels. I start the star pattern immediately....hand tighten, tighten a bit more with a wrench to approximately half the final torque. From there, I probably do overkill and do the final torque (100 ft. lb. for me) in three steps. I'm mindful about the weight of the vehicle on untorqued nuts, but not OCD about it. Your technique seems about right. The total length of a wrench can affect final outcome due to human error. Pulling 100 ft. lbs. on a short wrench takes more exertion than pulling on a longer wrench. More exertion can mean errors due to pulling crooked, etc.. Visit the tech pages at each of the major manufacturers for lots of tips: Proto, CDI/Snap On, Precision Instruments, Sturdevant Richmond.
 
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2,408
Location
CA
Originally Posted By: SumpChump
Great stuff folks! BTW, I wonder how tight finger tight is? I heard that HAND tight is about 10 foot pounds. 7 inch pounds must just mean 'screw it in with your fingers only'?
Nobody knows, because that's there is no service manual that will specify finger tight or hand tight. It's like saying a splash of Milk, or salt to taste.
 
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Messages
8,859
Location
Texas
Originally Posted By: SumpChump
Great stuff folks! BTW, I wonder how tight finger tight is? I heard that HAND tight is about 10 foot pounds. 7 inch pounds must just mean 'screw it in with your fingers only'?
Depends what you are tightening. I can tighten an oil filter much tighter by hand than I can tighten a 7/16 bolt. I can tighten the plastic wing nut that holds down the spare tire a lot tighter by hand than I can an actual lug nut. Not many people can grip a 3/8 hex nut tight enough with bare fingers to reach 7 inch-lb. most people could do it with a wingnut, though.
 
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11,660
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NorthEast
I purchased the HFT Torque Adapter; it is a fun tool to play with. I checked my 20 year old torque wrench. At 30 lb-ft, it was showing 26.5 but at 60 and 70, it was right on the money! When it is on sale (and with coupon) it is a ridiculously great deal. I think I paid less that $30 for that electronic torque adapter. If nothing else, it is worth just for checking the calibration of your expensive torque wrench.
 
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884
Location
Reno, NV
1. No difference. 2. Torque wrench accuracy is a percentage (usually 3% or 4% of setting) of setting from 20% of full scale to 100% of full scale. 3. Who knows what the engineer knows? 4. Good idea. 5. CDI among others. Not that uncommon. 6. Good idea. I calibrate torque wrenches for a living.
 
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1,555
Location
Oregon coast
Torque is not a measure of distance or speed. With an extension you may have to turn the wrench more to take up the torsional flex, but the same torque will eventually be reached, and then the wrench will read or click at the appropriate point.
 
Originally Posted By: 29662
1. no 2. depends on the quality of the tool. 3. yes they take that variable into account 4. sounds fine 5. just snug it down and don't worry about it. 6. I personally believe in torqueing incrementally. Particularly on high torque items. just my $.02
+1
 
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