how do the engineers for honda or any car manufature come up with spefic torque specs for every bolt on a car? Just one of those questions I was pondering.

thanks
mike

 

crank on it till it breaks knock it down a certain percentage and bam....torque spec.

lol j/k

they most likely determine the strength of the bolt and can determine how much to tighten it to.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Foozball26 &raquo;</TD></TR><TR><TD CLASS="quote">
they most likely determine the strength of the bolt and can determine how much to tighten it to.</TD></TR></TABLE>

That and the application of the bolt or nut.

 

They know the maximum design loads on the bolt, including thermal expansion. Add some safety factor...

How much will the bolt stretch under that load. Length, size, elastic modulus, etc...

Pick a value for bolt tension that will prevent the flange or whatever from lifting off under any combination of loads.

Then the first wild guess would be
Torque = 0.20 * Tension * nominal_diameter

But for a car manufacturer, I'm sure they make up some samples & try them. The 0.20 factor in that equation changes with lubrication or anti-seize. I bet a company like Honda can afford to destroy a few dozen bolts to test it. It's not good PR if that stuff keeps breaking.

Read your Helm manual. It says something like all bolts of a particular size have this standard torque; UNLESS it's specifically listed. I bet they don't do anything profound for most bolts on the car.