HIGH TORQUE FASTENING FOR DIYERS
Having got the June issue of Classics Monthly, I was interested to read on p14 in the Letters section the article by Nigel Cox regarding tightening the front hub nuts of the BMC 1100/1300 range of cars, and other things that he mentioned.
More years ago than I care to remember, I ran an Austin Allegro Mk2 estate, the successor to the 1100/1300 range of cars. For some reason I had to undo and re-tighten the front offside driveshaft hub nut. As is said in the article, most of us who do our own repairs do not own a torque wrench to do these nuts up tight enough, unless of course you work in a garage which would have had such a large torque wrench on hand.
How I overcame this problem is that the nut needed a 1½in AF socket, and this was 3/4in square drive. I did have an 18in and a 24in long square drive breaker bar, so using a 1/2in to 3/4in square drive adaptor and working out my own weight in pounds, I did the nut up as tight as I could by hand with a suitable 1½in spanner, then assembled the 1½in socket onto the breaker bar. I then stood on the very end of the breaker bar, of course having the wheels on the ground, and then gently rocked up and down steadying myself on the front righthand wing until the nut did not move anymore. This seemed to do the trick.
It is interesting to read how the average car owner, and indeed magazine like yours, overcomes such problems, bearing in mind that you can't have all the tools to hand that you would like, especially as you may only need a particular item once in a blue moon.
I have heard of a way of tightening up fixings to high torque figures which is very close to the method you described. That too starts by weighing yourself and measuring the length of your breaker bar, tommy bar, ratchet or spanner. From these two figures, you calculate how much of your weight you need to apply at any point along the bar to achieve the required lb.ft figure. Next, you stand on a pair of bathroom scales, apply force at the required point of the bar and watch the scales until you have lost the requisite number of pounds. I've never tried it, but it sounds like a reasonable plan! – Ed