Thread: Tightening Td5 crank damper bolt

Brilliant idea. Will use it when my Disco will need new crank pulley. Well done.

its a tried and true method which has been in use for ages.

but your engineer is a little off the mark....

under standard gravity a static 1kg is exerting 9.8 and a pumteenth of force.
46KG of force applied tangentially to the direction of rotation applies 451.10589999999996(pumteenths add up) Newtons of force which should be applied at 1m but you're applying it at 1.04m which means that effectively you are apppying 469.1501359999999584 newtons of force at one meter.

which means that if you've conducted a static recheck of the torque value (which means backing off the effort and then reapplying it) you have potentially overtorqued the bolt.

but hey, given the acceptable variance for a nominated bolt in automotive world is usually +/- 5% unless other wise stated you're in the ballpark.

couple of tips from when I do this stuff....

• Double check your lengths I usually use a longer bar with a lower effort as a small deviation on a long bar provides a smaller error compared to a the same deviation on a short bar
• Use the most accurate scale you can get your hands on. this goes hand in hand with the previous point, a scale that measures up to 10 KG in .1kg increments is going to give you better control than one that measures up to 50kg in .5kg increments.
• pull perpendicular to the lever. you'll be surprised at how quickly off square pulling reduces the effectively applied force I've gone as far as to weld a rod onto the side of the lever at 90 degrees so that if the cord I'm using to pull is bent over or not touching the end of the rod then I'm off center.
• Pull with the lever vertical. theres no super guuchi scientific mathsy reason for this its ergonomics and human nature. doing this trick on the vertical is easier than trying it on at 66.345 degrees and if its easy, you 're more likely to get it right.

Thanks for that, looking at his email it looks like he and I both made typo's about some of the values. He thought I was looking for 350 ft lb which converts to 474.5362825 Nm, so does that explain the slight overtension of the bolt I've ended up with.
Exciting stuff this physics, I almost studied engineering but ended up at seminary to become a hospital chaplain!
Dave