The ears that spread after tightening, what did you torque the bolts to?
I wanted the max clamping force I could get, so I looked up the maximum torque for dry, zinc-plated, Grade 8 fasteners here:
https://www.fastenal.com/content/feds/pdf/Torque-Tension Chart for A307 Gr5 Gr8 Gr9.pdf
For those conditions, it was 90 ft-lb. That's what I used, and I definitely wouldn't want to go tighter! When I re-did it this morning for those pictures, however, it wasn't that tight. Probably about 30 ft-lb (didn't use a torque wrench). Both times I used a Grade 8 bolt with a low-grade nut. The nut torqued to 90 was thrown in the trash (I considered it sacrificial).