check your lug nuts + torque wrench madness

[sparc]

If you had to take your torque wrench apart, I would question its accuracy.

Had interesting discussion with some thermo-mechanical engineers a while back. Most torque wrenches are never re-calibrated after they leave the factory; typical spec is yearly. Most TQ wrenches should be stored properly, with tension relived; ie don leave it at 95ft/lbs or whatever you last use was. An, most TQ wrenches, even if they have a lot of adjust-ability(ie 50-250 ft/lbs) are only accurate in the middle of that range; as you get to the lower range or higher range of the wrench, the accuracy drops off, sometimes significantly. Then there is level of quality of the wrench; don't expect a Harbor Frieght 50% off sale TQ wrench to read like a just calibrated Snap-On.

DON'T set your wrench to Zero, set its 'at rest' setting to 10% of its RANGE. So a 0-100 would be set to 10, a 50 to 250 (200 range) would be set to 10% of 200 + 50 so it gets an 'at rest' setting of 70. If you won't be using the torque wrench for more than one hour, return it to its 'at rest' setting.

Torque wrenches at one place where I worked were calibrated every six months minimum. For special jobs they get calibrated right before use and the cal gets checked in the cal lab right after use. All other torque wrenches get checked by the user with a Snap-On torque wrench checker before and after use. The torque checkers are calibrated every 6 months. Each torque wrench has a stricker on it that tells you its usable range. That range is particular to that individual wrench; meaning that the same model wrench may be usable to a lower setting; its all governed by where it falls out of tolerance when they calibrate it.

Evey job a torque wrench is used on the wrench ID number is recorded. If when the wrench gets back to the cal lab it fails its as found test, ALL jobs where that wrench was used back to the last time it was cal'd will need to be evaluated to see if it is necessary to go back and re-check the torque with another wrench. Wrenches calibrated for use in a forward (tighten) direction can not be used in the opposite direction. Wrenches that get wet (as in partially or completely submerged) are usually trashed as they will never perform reliably afterward.

 

[RobertN]

I went by the book on mine; it is out in the garage...

I work in electronics, where most measurement equipment is cal'd, removed from service, and retest is done if it was outside of Cal...

I should ask the Cal lab at work if I could bring my torque wrench in and try it on their test stand... I think all their stuff is for the other end of the spectrum; very very light torque settings.

I'm not even sure where you would look up cal info for older Craftsman stuff.

DON'T set your wrench to Zero, set its 'at rest' setting to 10% of its RANGE. So a 0-100 would be set to 10, a 50 to 250 (200 range) would be set to 10% of 200 + 50 so it gets an 'at rest' setting of 70. If you won't be using the torque wrench for more than one hour, return it to its 'at rest' setting.

Torque wrenches at one place where I worked were calibrated every six months minimum. For special jobs they get calibrated right before use and the cal gets checked in the cal lab right after use.

 

[5030]

If you had to take your torque wrench apart, I would question its accuracy.

Had interesting discussion with some thermo-mechanical engineers a while back. Most torque wrenches are never re-calibrated after they leave the factory; typical spec is yearly. Most TQ wrenches should be stored properly, with tension relived; ie don leave it at 95ft/lbs or whatever you last use was. An, most TQ wrenches, even if they have a lot of adjust-ability(ie 50-250 ft/lbs) are only accurate in the middle of that range; as you get to the lower range or higher range of the wrench, the accuracy drops off, sometimes significantly. Then there is level of quality of the wrench; don't expect a Harbor Frieght 50% off sale TQ wrench to read like a just calibrated Snap-On.

I checked a newly purchased HF wrench against my recently calibrated Snap-On dial wrench and it was within 2 foot pounds across the entire range.

Actually, I was amazed as well. The HF wrench cost a whopping 22 bucks. The Snap-On was almost 500 bucks.

 

[5030]

I went by the book on mine; it is out in the garage...

I work in electronics, where most measurement equipment is cal'd, removed from service, and retest is done if it was outside of Cal...

I should ask the Cal lab at work if I could bring my torque wrench in and try it on their test stand... I think all their stuff is for the other end of the spectrum; very very light torque settings.

I'm not even sure where you would look up cal info for older Craftsman stuff.

It's in the round file.......:laughing:

 

[5030]

As mentioned, do not store you wrench set, zero it back.

As far as lug nuts on trailers go they should be torqued to 120 ft lbs. I have over 75 trailers I maintain and have owned over 20 personally and all have required them to be torqued to 120 ft lbs.

Chris

Maybe all of yours but to say that as a blanket statement is false.

Fastener torque depends entirely on application, the material the wheel is made from (alloy versus steel), stud diameter and type of fastener (pilot bolt or conventional stud/nut assembly.

If you torqued a 10 hole Alcoa Aluminum 24.5" rim to 120 foot pounds, it would seperate from the hub in no time. Recommended torque on that particular wheel is a minimum 400 foot pounds. Conversely, the recommended torque on the alloy wheels on my Chevy Tracker is 85 foot pounds.

All depends on the application......

It's what that book that no one reads if for......the owners manual.

On the subject of torque wrench's, that wrench banging around in your tool box is probably miserably out of calibration. Wrench's need to be calibrated at least yearly in commercial service, more often in critical applications.

 

[SPYDERLK]

It should be a concern with anything that has wheels. When new lugs are torqued cold, they will stretch when subjected to a couple of heat cycles, even if the nut doesn't turn, they will loosen.

Re-torque and THEN put on your paint.

What you are seeing there is a settling into the hub of the lug and the wheel, not a stretch of the lug. Otherwise yould be seeing engine bolts requiring re torque. Head bolts can benefit cuz of gasket settling, but metal to metal like rods and mains dont need it.
larry

 

[s219]

If you had to take your torque wrench apart, I would question its accuracy.

I only had to take the ratchet head apart -- that was the part that was sticking.

 

[Diamondpilot]

I checked a newly purchased HF wrench against my recently calibrated Snap-On dial wrench and it was within 2 foot pounds across the entire range.

Actually, I was amazed as well. The HF wrench cost a whopping 22 bucks. The Snap-On was almost 500 bucks.

I have done the same thing. I have 2 of the HF 1/2" wrenches and two times a year the guy comes to calibrate our stuff, MAC and Snap On at the airport. One was dead on and the other was 4# off. Good enough for me. The guy who does the calibration was amazed a $9.99 on sale torque wrench would be so good.

Chris

 

[Diamondpilot]

Maybe all of yours but to say that as a blanket statement is false.

Fastener torque depends entirely on application, the material the wheel is made from (alloy versus steel), stud diameter and type of fastener (pilot bolt or conventional stud/nut assembly.

If you torqued a 10 hole Alcoa Aluminum 24.5" rim to 120 foot pounds, it would seperate from the hub in no time. Recommended torque on that particular wheel is a minimum 400 foot pounds. Conversely, the recommended torque on the alloy wheels on my Chevy Tracker is 85 foot pounds.

All depends on the application......

It's what that book that no one reads if for......the owners manual.

On the subject of torque wrench's, that wrench banging around in your tool box is probably miserably out of calibration. Wrench's need to be calibrated at least yearly in commercial service, more often in critical applications.

I understand that, but we are talking trailers here. My Titan for example takes 98# and my F-350 calls for 160#.

Standard trailer stuff that I have worked on for 20 plus years are all 120# with the standard 1/2" 20 studs which 99.5% of all bumper pull, GN, and 5th wheelers I have worked on have. I have replace more than 100 studs in my time. I keep about a dozen of them and lug nuts on hand for replacement.

Chris

 

[5030]

I understand that, but we are talking trailers here. My Titan for example takes 98# and my F-350 calls for 160#.

Standard trailer stuff that I have worked on for 20 plus years are all 120# with the standard 1/2" 20 studs which 99.5% of all bumper pull, GN, and 5th wheelers I have worked on have. I have replace more than 100 studs in my time. I keep about a dozen of them and lug nuts on hand for replacement.

Chris

... and I understand that as well. What I'm stating is that a catchall torque value really don't apply. 120 foot pounds is a good starting reference but the owners manual or 'torque to tag' on the trailer is a better yardstick, but that entails some reading.......

I realize thats an added burden for some people.....