DSCN1288.JPG;Initially I just bought a new latch but decided to go a different route instead|||DSCN1289.JPG;|||DSCN1290.JPG;The new latch is well built and heavy duty. I am impressed.|||DSCN1291.JPG;|||DSCN1292.JPG;|||DSCN1293.JPG;Red+Black is for unlocking. White+Blue is for checknig lock status|||DSCN1294.JPG;Can be manually unlocked with either the left screw or the bottom lever|||DSCN1295.JPG;|||DSCN1312.JPG;Will replace original shaft on left with the new roller latch on right|||DSCN1313.JPG;|||DSCN1314.JPG;|||DSCN1315.JPG;|||DSCN1316.JPG;|||DSCN1317.JPG;I ended up cutting down the sides even more|||DSCN1319.JPG;|||DSCN1320.JPG;|||DSCN1322.JPG;|||DSCN1323.JPG;|||DSCN1324.JPG;Trimmed down the metal more. Still far more substantial than original bolt|||DSCN1326.JPG;|||DSCN1327.JPG;Bolt is contacting hole in body. Had to expand the hole in the body|||DSCN1328.JPG;|||DSCN1330.JPG;|||DSCN1332.JPG;|||DSCN1333.JPG;That is the depth I need|||DSCN1336.JPG;Time to make a mounting bracket. I start with some 1|||DSCN1337.JPG;|||DSCN1338.JPG;|||DSCN1340.JPG;|||DSCN1341.JPG;|||DSCN1342.JPG;|||DSCN1343.JPG;This was a little on the small side. For the other latch, I made the mount longer|||DSCN1344.JPG;|||DSCN1346.JPG;I couldn't bend 1/8|||DSCN1347.JPG;|||DSCN1348.JPG;|||DSCN1349.JPG;|||DSCN1350.JPG;I welded some nuts on the inside of the square tube|||DSCN1352.JPG;|||DSCN1353.JPG;|||DSCN1355.JPG;|||DSCN1356.JPG;|||DSCN1357.JPG;|||DSCN1359.JPG;Roughly mounted in place to check the location and operation|||DSCN1365.JPG;Bolt will need to be shortened substantially|||DSCN1367.JPG;I welded on nuts of the same size as the OEM bolts so I could reuse the rear bolt and rubber cap|||DSCN1368.JPG;|||DSCN1369.JPG;I made the left bracket longer. No need for it to be short like the right side|||DSCN1370.JPG;I decided to weld on a part so I could keep the original trunk release lever |||DSCN1372.JPG;|||DSCN1373.JPG;|||DSCN1374.JPG;The nut welded on is simply to hold a bicycle cable adjuster|||DSCN1375.JPG;The cable will pull back on the screw which manually releases the lock|||DSCN1376.JPG;Bead blasted and ready for powder coat|||DSCN1377.JPG;Went with Eastwood Mirror Red powder coat|||DSCN1378.JPG;Powder coating always makes my fabricated parts look so much better|||DSCN1379.JPG;|||DSCN1380.JPG;|||DSCN1381.JPG;Finally cleaned all the old grease and gunk from the body|||DSCN1382.JPG;New latch installed in mount and ready to install on car|||DSCN1383.JPG;|||DSCN1385.JPG;You should make your mount longer so you don't pinch the wire I have|||DSCN1386.JPG;|||DSCN1387.JPG;|||DSCN1388.JPG;I installed an SAE cable on the batter and ran it out the trunk floor. Just in case...|||DSCN1389.JPG;I can charge the battery without openin the trunk. Unecessary but nice.|||DSCN1394.JPG;I added a couple more leads, this time for the keyless entry I will mount on the battery|||DSCN1395.JPG;That looks sexy. Maybe not a factory job, but certainly not ugly either|||DSCN1396.JPG;I even powder coated the fender washers|||DSCN1397.JPG;I can't believe how cheap keyless entry systems are now. This was only $20|||DSCN1398.JPG;One regret, I should have found one with keyfobs with recessed buttons|||DSCN1399.JPG;|||DSCN1400.JPG;|||DSCN1401.JPG;|||DSCN1402.JPG;|||DSCN1403.JPG;|||DSCN1404.JPG;My emergency release cable|||DSCN1406.JPG;On the new latch, this lever already had a hole in it. Perfect.|||DSCN1407.JPG;I ran the wire down and out the trunk floor. I am being overly paranoid.|||DSCN1409.JPG;|||DSCN1411.JPG;Oh and I changed the oil while too|||DSCN1412.JPG;|||DSCN1413.JPG;|||DSCN1416.JPG;|||DSCN1418.JPG;|||DSCN1419.JPG;|||DSCN1420.JPG;|||DSCN1421.JPG;Keeping the original cable operated trunk release means splitting the cable|||DSCN1422.JPG;This Porkchop branded bicycle cable splitter is perfect|||DSCN1423.JPG;Original latches were spring loaded. New ones aren't. So you have to add a spring to the splitter|||DSCN1425.JPG;I just cut some random spring that had about enough tension according to my calibrated hand|||DSCN1426.JPG;|||DSCN1427.JPG;|||DSCN1428.JPG;Just cut the original cable, run into the splitter, and screw it down|||DSCN1429.JPG;|||DSCN1431.JPG;|||DSCN1432.JPG;Now you get the idea|||DSCN1433.JPG;Finding a spot to mount the splitter took me a whil|||DSCN1434.JPG;|||DSCN1440.JPG;I probably should have fabricated a mount for the splitter on my latch mount. Zip strip to the rescu|||DSCN1445.JPG;|||DSCN1448.JPG;The relay that lets the keyless entry system energize for a split second but operate the lock|||DSCN1449.JPG;Which takes 2 full seconds for its cycle|||DSCN1450.JPG;|||DSCN1471.JPG;|||DSCN1472.JPG;|||DSCN1475.JPG;3D printed project box to hold that mess.|||DSCN1478.JPG;Not bad looking|||Stevens Esprit Keyless Trunk Release.png;|||electronic_rotary_push_to_close_latch.jpg;|||keyless-entry.jpg;|||AlbumDescription;

The trunk of my 1990 Lotus Esprit SE was stuck. The pull release was not releasing the right latch. I put in some serious troubleshooting time a few weeks ago to get it working again. Read about that adventure here. 

Unfortunately not but a week later and the trunk wouldn't open again. Initially I just ordered a new OEM latch. But that could fail just like the original. I wasn't sure if the problem was the latch or the alignment. I decided to do something more drastic. I would replace the latch assembly entirely. And if I was doing that, it sure would be nice if I could open the trunk electronically.

I checked the forums and found people that had installed solenoids to pull the cable to operate the original latch. I found people that skipped the solenoid and used linear actuators instead. In all cases though, they were using the same latch assembly I no longer trusted.

I went a different direction. I bought an "electronic rotary latch" off Amazon. These things are used on amusement park lockers. Here is the exact link. It can be opened with 12 volts, but also has two mechanical releases. Ultimately I was able to connect it up to a keyless entry system, while still allowing the original in-car manual trunk release to work, and also an emergency trunk release pull cable accessible under the car. 

Ultimately i am extremely happy with how this turned out. I have multiple ways to open my trunk, the alignment of the new latch is extremely easy and it holds tight. 

There were a couple downsides. First, you have to fabricate your own mounting brackets. No surprise there. Second, the latch opens with 12 volts but requires 12 volts for 2 full seconds of voltage to go through a complete locked to unlock to ready to lock cycle. No keyless entry system in existence provides 12 volts for that long. So you need to incorporate a timer relay that holds the voltage on for 2 seconds. Slightly more complicated and expensive, but not too bad.

Full build list

  1. Electronic Rotary Latch (x2), $60 each
  2. Accelle BU-509TD 30 amp adjustable time relay, $35
  3. Porkchop BMX Porkvert bicycle brake cable splitter, $20
  4. Generic car keyless entry system, $20
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