"In any case, fine-thread fasteners will require a higher torque value than a coarse-thread fastener of the same size (check the manual)"
Usually, finer thread bolts are made with material of a much higher tensile stress allowable, allowing a higher installation torque in order to develop a higher assy preload, with better torque application control.
Interestingly, I've seen very fine rolled thread 4340M bolts of 275-300 ksi tensile allowable on aircraft, something a car will never see. Trouble is with those materials is that they are like glass, in that if there is any defect, grinding nick, whatever, they crack almost instantly due to an absurdly low fatigue life. Undamaged, however, they have superb high load service life.
1989 Milano, Shankle Sport
1991 164S, stock
1994 164LS (~Q)
1972 Morgan 27
previously owned since 1964:
62 Morris MiniMinor 850, 67 Austin 1275 Cooper S (Downton 3/4 race), 64 Giulia Sprint GT (1st red one made), 72 Fiat 128 Sedan, 75 Alfetta Sedan, 78 Alfetta Sedan, 78 GTV, 81 GTV6, 86 GTV6
Last edited by Del; 06-26-2018 at 10:07 PM.