I started on the left gear leg engine mount attachment point. I needed a thin washer and a thick washer to get the hole in the bolt to line up correctly with the castle nut when torqued properly. I put the thin washer at the head of the bolt which allowed me to put the thick washer at the threaded end. The bolts still end up a bit long and the end of the bolts want to rub the firewall. I ended up putting a large flat washer or “fender washer” over the end of the bolt to provide a large bearing surface against fire wall. I saw this on another Sonex and it looks like it works. The cotter pin does not seem long enough. I’m planning to order some additional cotter pins that are longer for this bolts. I’m not sure why, but the Sonex specified cotter pin is a 5/16 inch diameter but the standard cotter pin for the AN4 bolt is only 1/8 inch diameter which would fit nicer. I’d also like a longer cotter pin since I need to wrap the legs around the nut instead of over the top. When putting the cotter pin in 90 degrees to the bolt it does not go into the castle nut as far as I would like.
I also installed, torqued and cotter pinned the fasteners in the lower end of the main gear legs for the front axles. This was easy but I needed two thick and two thin washers. I considered using a shorter bolt but I was not happy with how far the bolt came through the axle mount. I used the longer bolt so that the shank of the bolt was fully engaged in the mount to minimize the possibility of the holes becoming oval over time.
I went back to the wheels. Previously, I had assembled one of the wheels and found that the valve stem ended up very crocked. I wasn’t happy with the assembly. This time I made sure the valve stem was through the hole in the rim with the rubber resting against the rim. This time when I inflated the tire to 30 psi the stem remained straight. With one wheel assembled I proceeded to the second wheel. The bolts holding the wheels together are 5/16 inch diameter so I torqued them up to 85 in-lbs per the Standard Aircraft Handbook. I made sure my compressor was set to a max of 30 psi since this is the limit stamped on the side of the rim.