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Date:         Tue, 27 Sep 2011 22:27:08 -0700
Reply-To:     Scott Daniel - Turbovans <scottdaniel@TURBOVANS.COM>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Scott Daniel - Turbovans <scottdaniel@TURBOVANS.COM>
Subject:      Re: Torque Specs - Lug bolts and nuts
Comments: To: Gary Bawden <goldfieldgary@GMAIL.COM>
Content-Type: text/plain; format=flowed; charset="iso-8859-1";
              reply-type=original

There are electronic torque wrenches now.

here's just one http://tinyurl.com/6zv99o6

or search 'electronic torque wrench.'

the craftsman one above ( $ 180 ) sounds pretty fancy.

Scott turbovans ----- Original Message ----- From: "Gary Bawden" <goldfieldgary@GMAIL.COM> To: <vanagon@GERRY.VANAGON.COM> Sent: Tuesday, September 27, 2011 8:51 PM Subject: Re: Torque Specs - Lug bolts and nuts

> Whatever current Proto torque wrenches claim, I'm not sure. But at the > time, > I had access to a torque wrench tester, and had drawn a curve for my > wrench > vs. the actual reading. IIRC it was fairly close in the middle of the > range, > but quite a bit off (like almost 20%) at the high and low ends. This was a > clicker-style wrench from the 1970's, 1/2" drive, 250 lb-ft capacity. > > The point is, torque wrenches are not laboratory instruments - - you > should > expect them to have a tolerance, just as one should expect EVERY measuring > instrument (even laboratory instruments) to have a tolerance, which is > another way of saying, they may be off by a certain amount. Just a part of > basic awareness, one should know what sort of tolerance to expect from > whatever you are using to measure anything that is measurable. That being > said, at the time, a beam-type torque wrench was considered to be more > accurate than a clicker-style torque wrench, but as I mentioned in my > previous message, just how many people took care to get a proper reading, > i.e., without a parallax error? I remember that the Snap-On torque > wrenches, > the beam type, had optional electrical contacts that would turn on a > light, > or sound a beep, at the selected torque value, and if I remember > correctly, > Snap-On claimed 5% tolerance for their wrenches. Not everybody could > afford > Snap-On, however! > > I believe the engineers know this, and set torque values to a number that > they believe will do the job, without over-stressing the part. And as has > been pointed out by others, it's the uniformity of torquing fasteners (at > least on parts having more than one) that is probably more important than > the actual torque value. So if you are using a reasonably good torque > wrench, even if it may be off by quite a few percent, it is probably > repeatable, which is a different thing than being accurate. In other > words, > if all five lug nuts, for instance, are torqued to the same value, and are > in the proper range of torque, that is probably more important than > whether > or not they are all torqued to 118 lb-ft, or 133 lb-ft. But as I am not an > engineer, it is just IMHO! > > And just for grins, I think I may still have one of the old Proto > catalogs, > so I'll look and refresh my memory of what they claimed for that era. > Also, > I should point out that the statement, "the technology in clicker-type > wrenches hasn't changed", may be true, but the technology MAY have been > refined. :^) > > Gary > > >> At 12:02:24 27 Sep 2011, Mike S <mikes@FLATSURFACE.COM> scribed, >> >> I'm not sure Gary's remembering accurately. Current Proto torque >> wrenches are "Calibrated to +/-3% in clockwise direction and +/-6% in >> counter clockwise direction," so much better that 20%. The technology >> in "clicker" type wrenches hasn't changed. If you don't get them >> calibrated occasionally, or don't reset them to the minimum setting >> after every use, then the calibration could be off, but probably not by >> 20%. >> > > At 07:35 PM 9/26/2011, John Rodgers wrote... >>If Gary Bawden's plus or minus 20% rule applies - the would be low >>-98.4 >>ft-lbs and high - 147.6 ft-lbs and that figure is a whole bunch!


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