On May 16, 3:23*pm, joesimmers wrote:
I have a cobra glass top of this vintage so this has my interest.

Did the bolt break or shear at the location where the thread ends and
solid shank starts?

Where the new bolts you used "grade 8"?

I would not use stainless bolts as they are softer and will shear much
easier than
a "grade 8" heat treated bolt.

By the way 5/16" is exactly the same size as 8mm, difference is only .
002, less
than a hair thickness. And I would trust the heat treatment of a grade
8 *5/16" bolt over a class 12.9 metric bolt.

I think I would get bolts long enough to have a solid shank all the
way thru the structure causing the misaligned stress
you decribe and only enough thread on the back side to hold the washer
and nut.

I'll be checking mine if it ever quits raining.....................

Joe Simmers

My bolt failed at the thread to plain shank intersection. I have not
yet found the nut and threaded end. The plain shank length of the
original bolt is far too short and any shear load it taken at the
intersection rather than on the full shank diameter.

I don't know what grade the replacement bolt is. At the time I was
very pleased to find there was a hardware store within 10 miles of the
glider port. I have been flying there for over 20 years and had no
idea the store was there. To then find they had socket cap bolts of
the required size and length was beyond my expectations.

For the emergency repair at the glider port I was able to insert a #2
Phillips screw driver to pin the parts and then open the trailer. I
had 4 people at the aft end holding the top up and one person pulling
down on the front of the top. That allowed the bolt to slip in. Had
the other bolt failed it could have been ugly.

GW inserted a new bolt in his solo with the help of a clamp to pull
the parts into alignment. I had people available but no clamp.

Andy (GY)