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*To*: quattro@coimbra.ans.net*Subject*: Torque Wrench adapters...*From*: quk@sievers.com (Phil Payne)*Date*: Wed, 26 Feb 1997 17:12:27 GMT*Reply-To*: phil@sievers.com*Sender*: owner-quattro@coimbra.ans.net

In message <199702261510.AA01889@igw.fmc.com> christopher_bender@fmc.com (CHRISTOPHER BENDER) writes: > I've been listening to a lot of talk about this subject recently, and > so far only one guy has got it right. Two, actually. One being me. > I forget his name, but he concluded his proof with "Q.E.D.," ... See below. > A guy claiming to be a mechanical engineer tells us > that the torque calculation has nothing to do with the length of the > torque wrench. Hello?!? This is simple statics! How long ago did > you have the course??? Well, I'm getting fed up with the ignorance, > and I am gonna take a stab at it. And get it wrong ... > It's real simple. Torque varies linearly in a cantilever beam. A > wrench is just that: a cantilever beam. Torque is theoretically > maximum at the base (the fastener being torqued) and is zero at the > point of application (The end of the wrench that you push, pull, stand > on, etc.). It varies linearly between the two ends for any point of > interest in between. So, when you use an extension, you have to scale > up the torque LINEARLY by the ratio of the total length (wrench plus > extension) to the length of the wrench alone. Wrong so far, but carry on. > But what does this mean to us Audi people trying to use tool 2079? > Well, it means, that the torque specification given by Mr. Bentley is > conceptually flawed. To specify a torque of 258 lb-ft with tool 2079, > but without specifying the torque wrench to be used, is wrong because > they have to make an assumption of the length of your torque wrench. No. Mr Bentley is not actually the source for this information - it's Mr Audi. I quote from "Reparaturleitfaden Audi quattro 5-Zyl. Einspritzmotor", Audi publication number 000.5148.29.00, Reparaturgruppe 13, Absatz 13-6: "Anzugsdrehmoment 350Nm mit Sonderwerkzeug 2079 und 2084 Anzugsdrehmoment 450Nm ohne Sonderwerkzeug 2079" 350Nm is 258 lb ft, and 450Nm is 332 lb ft. Now - I don't personally care a flying **** _HOW_ Audi reached these values - but both are documented for the I5 engine. 400 lb ft is 20% over-torque, assuming that your torque wrench is accurate. > I'm sorry if I'm sounding rude, and I hope you all will keep the > flamage to a minimum, but I have just been hearing way too much on > this relatively simply subject, and I am getting tired of it. Me too, especially from amateur applied mathematicians. Oh, and Q.E.D. -- Phil Payne phil@sievers.com Committee Member, UK Audi [ur-]quattro Owners Club

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