I reviewed a number of articles on the forum and the web to see how others approached releasing a “bear claw” latch. There were many fine approaches. There seem to be two reasonable ways to release the trunk latch: (1) using a motor actuator, or (2) a brute-force solenoid.
Although it used a lot of power, the solenoid seemed more reliable in the long term than the motor. I had just installed motors in the doors, and I had my doubts on their work-life. Using the solenoid approach also made sense because I already had 30 amp capacity in the trunk feeding my stereo amplifiers. I used a heavy duty 30 amp double pole relay to release the solenoid. A #8 wire feeds the trunk from a 30 amp central fuse box directly from the battery for upgraded accessories, and a #10 wire fused at 20 amps serves the release relay and is fused at 20 amp slo-blow- absolutely necessary for the solenoid draw.
Before I purchased the solenoid I used a spring scale attached to the trunk release lever to determine how many foot-pounds would be necessary to release the trunk. If I recall correctly it was approximately 45 pounds, quite a shock.
I found a supplier online from which I purchased my first solenoid that had this rating. I quickly found out that the rating was cited for the end of the stroke, and not the start to stroke- major difference! I located another provider that had a solenoid that appeared better mechanically and electrically more capable and I purchased the device for about $45.
One of the first challenges you have with a solenoid is both the start pull capacity as well as the stroke length. I determined that I needed a minimum of a three-quarter inch stroke at the 45-50 lb rating. My second candidate worked well.
I also determined that two other important factors in making this work: (1) securely mounting the solenoid to assure there was no slack or lost effort, (2) providing A fine adjustment along with a way to absorb the massive shock of the instantaneous pull of this big solenoid.
To accomplish this I used a “10 lb” 4” spring, a rubber grommet, and a turnbuckle. This allowed me to make the adjustments necessary to fine-tune the assembly, and also to absorb unnecessary shock to the release lever. Please check out the pictures and the accompanying text.
The tension spring is attached at the existing trunk release lever base just below the latch return spring. This thing really needs a lot of energy to release!
A long-throw alarm switch was installed so it could be easily adjusted to determine if the trunk lid was attacked and pried open.
I hope this approach might be useful to someone contemplating the same.