Radius and shock bolts

This may be a silly question but can anyone explain why Radius arm and shock bolts have to be metric fine and 1.25??

Cheers

No reason, the ones I sell are standard M12 bolts... (so 1.5mm "coarse" thread)

M12 x 100 for the radius arms
M12 x 70 for the shock bolts (front lower)

www.bits4vits.co.uk/store/index.php?sear...mny+bolts&_a=viewCat

Also sell the same thing (M12 x 100) for Vitara rear trailing arms and the front wishbone mounts (the rears are M14)...

Thanks, think I'll get some ordered,

Just what is the specification for these radius arm bolts?

I called Namrick today and was told of various available thread coarse levels but did not have this link or details to hand. www.namrick.co.uk/acatalog/Home_Metric_F...T_Head_Bolts_29.html

I was even confused by their washers www.namrick.co.uk/acatalog/Metric_Plain_washers.html where they have different forms.

Only reason I can see is that it's a superior thread to a 1.5 or 1.75 pitch for the purpose it performs.....engineering wise.

Bolts are all in the store = www.bigjimny.com/store/jimny-parts/bolts-and-hardware.html

From the Internet:

Fine threaded bolts are stronger than the corresponding coarse threaded bolts of the same hardness. This is in both tension and shear due to the fine threaded bolts having a slightly larger tensile stress area and minor diameter.

Fine threads have less tendency to loosen under vibration due to their having a smaller helix angle than coarse threads. Fine thread Locking Insert grip coils are more flexible than coarse thread insert corresponding size grip coils, and are less likely to take a set under vibration conditions.

Fine threads because of their finer pitch allow for finer adjustments in those applications that need this characteristic.

Fine threads can be more easily tapped into difficult to tap materials, and thin walled sections.

Fine threads require less tightening torque to develop equivalent preloads to the corresponding coarse thread bolt sizes