NISMOnator wrote:Thank you for the answers that really helps.
I went for the 8.8 as that was what was in there with the galvanized ones. The black ones.
Peter may I ask what is the main difference between High Tensile and other bolts like the galvanized ones?
I found the thread on the High Tensile to be deeper cut as the galvanized ones?
Jacques, there really shouldn't be any difference in thread form between different bolts of the same nominal thread size. In other words, any two M10 x 1.75 bolt's thread should be exactly the same (although of course there are allowable limits (manufacturing tolerances) that allow for minor differences). The real difference between the different bolts is in the materials they are made from, and particularly so in terms of their strength.
Quality Metric bolts should have a code on the back, this is called the grade. Normal galvanized bolts are grade 4.6
To use the code is sort-of simple, the first number multiplied by 100 is the Ultimate Breaking Strength (this is where it will break) of the bolt, in MPa. If you multiply the above number by the second part of the number, you get the Yield strength (the point at which it will start to permanently deform or bend/stretch).
So a grade 4.6 bolt will start stretching at 400 x 0.6 = 240MPa, while a grade 8.8 bolt will stretch at 800 x 0.8 = 640MPa, or nearly thre times the load.
The difference in thread depth you found is probably due to the galvanising being thicker in the thread grooves.
Mag ons ons kenniskry met lekkerkry aanhoukry.