I use the spring gauge method on both mine. Seems to work. It is how they tell you to do it in the Isuzu Workshop manual for both the Gen 2 Rodeo (Frontera B Series) and all the Troopers. There are two values depending on whether they are new or re-used ones:
New:
20-25 N (2.0-2.5 Kg m : 4.4-5.5 Lb)
Old:
12-18 N (1.2-1.8 Kg m : 2.6-4.0 Lb)
Like you I was skeptical, but then it is the sort of basic and simple thing Isuzu comes up with for doing stuff.












