anyone have a good link for an online source for bolt strengths
with yield strengths in single and double sheer etc.
thanks

http://www.nutty.com/tech.html

http://www.nutty.com/torque_chart.pdf

http://www.camcar.textron.com/NewHTML/grades.html

http://www.engineersedge.com/hex_bolt_identification.htm

thanks for the links Dan-H
but i still couldn't find the sheer load ratings.(maybe I'm a dumbass)
I did a google search and found 39,760# for a grade 8 3/4" bolt in single sheer but I'm hoping for a chart telling rating for single and double sheer for different grade and size bolts.

I just grabbed some links I had filed and posted them. I *assumed* they had the shear...

try this one. http://www.hobson.com.au/class_8.htm It doesn't have double, but I think double shear depends on more than just the bolt.

Just so we are both saying the same thing, double sheer is the weight to break a single bolt supported in two places into three pieces, right?

So at best double sheer is twice that of single shear, but could be much less depending on the actual assembly. I have an old statics book in the garage that probably had the formula but basically if the distance between the shear points is twice the thickness of the bolt then you should be close to double the shear.

But keep in mind single sheer force is measured for the unthreaded portion of the shank and not the threaded portion which will be a smaller number so that second part won't be as strong and this is where the bolt will likely fail. Also keep in mind if the shearing force is put directly on the trhreads, they will crush and kill the bolt so make sure the shear force is applied to a nut (i.e a welded nut) that carries the load.

so,... what cha buildin?

yeah I found that link too.
I mostly was curious to see what the sheer rating was for a 3/4" bolt in single and double sheer which is being used for rear lower control arms in a 3-link suspension. I built mine in double sheer but I know others with the same setup only in single sheer and wanted to know the difference in the sheer rating; as well as for a future reference for other thought that go through my mind.

The shear strength of most fasteners is only about 60% of their tensile strength. If the joint is arranged so that the fastener is in double shear, so the material has to be severed in 2 places for the fastener to fail, then it can carry a greater load than it can in tension.

This doesn't take into account concerns about free play arising from the clearances necessary for insertion of the fasteners through the parts (a role SAE bolts are ill suited too)

Translation:

single shear strength - 60% of tensile
double shear - assume = to tensile.
use the righht close tolerance (e.g. AN, etc.) bolts in precisely machined (drilled rough undersize and reamed to final size) holes for critical joints.

Or do as most of us do - and use parts and fasteners so hugely over spec that theory goes out the window !