You can see that the hinges are a small part of hinging the rear clam. My rear clam is very solid, no vibration or cracking - as solid as OEM. It takes around 10 seconds to swing the clam open which is great for engine work. < 2 minutes to completely remove the clam - pull 4 pins and one electrical connection (rear brake/directionals) and remove!
I don't have CAD drawings of the hinges - I cut them from 3/8" aluminum plate using a hacksaw and a LOT of patience.
Are your hinges similiar in design to the Hyper-Motorsports ones (see pic below)? It looks like they use the existing rear most channels on the galvanized sub-frame as the lower part of the hinge. Where are your four pins? Two in the trunk and two in front of and at the top of the rear window (inside)? It appears they added two gas struts to assist and support the clam when open.
2006 Lotus Elise - Solar Yellow, HT, LSS, LSD/TC, Touring, StarShield, S111 RTDbrace, S111 microMirror, S111 Carpet Buttons, Painted A/C Surround, CF Center Console, Nitron S/A, Tempest BAB26-12 AGM Battery, Fujita Intake, Top Speed Pro 1 Exhaust, 4Tress Harness Bar, JDM ASTAR Cree H1 LED Headlights, Plinthless front clam, BRIDGESTONE POTENZA RE-71R 205F/235R on LSS Wheels, Heater Core By-Pass, Shifter Reinforcement, LETSLA v2 Shift Kit