Dennis,

The shank is 3/4" dia but the threaded portion is smaller.  The Legacy wing bolts (P/N 4510) are described as 3/4x2x5/8-11.  I measure a nominal threaded diameter of 9/16" and 11 threads per inch, though I'm guessing by the description that it's a 5/8 thread at the end of a 3/4 inch diameter 2-inch shank.  The standard torques from the link you mentioned are still significantly greater than that called for in the build manual.

BTW, I wouldn't go as far as saying that the bolts don't take any shear load themselves.  I'm not sure if the designer(s) intended for the bolts to take all the required shear themselves with the friction along for the ride (added margin) or if the clamp-up friction was intended as a necessary source of strength,  In either case I'd expect the bolts to see some shear.  I also second what Rob Wolf said about additional tensile load due to aero loads not taken solely by shear at the main and aft spar bolts.  If you can't get 40 ft-lbs, ensure that the a minimum torque (if Lancair can provide such) is attained on these bolts.  Let us know if you find such numbers.

As an aside, I've noticed that torques are specified for the bolts that mount the engine mount to the firewall.  Besides these and those for the wings, are there other bolts on the Legacy that require exact torques?

 Cheers,
- Kyrilian
  L2K-236

Dennis Johnson <pinetownd@volcano.net> wrote:

I'm not 100% sure I remember right, but I think the bolts are 3/4" diameter and when I look that up in the standard torque tables, the torque ranges from 155 pound/feet for a low grade bolt to 380 pound/feet for a grade 8 bolt.  http://www.thelenchannel.com/1torque.php  No way could I achieve that much torque in such a cramped space, but I probably got more than the 40 pound/feet I needed. 

<snip>

(But I was clearly wrong to say that the bolts were loaded in shear, which they aren't.)

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