How To Install a Miata Trunk Lift Kit

Watch as Underdog Garage installs a trunk lid lift kit for a 2003 Mazda MX5 Miata.

First we set up a bungee cord hung from the garage opener to hold the Miata's trunk lid open. Then we started removing the trunk carpet, storage, and rear trim. Next we removed the metal panel in the rear that covers the fuel filler neck. Once that was removed we could access the trunk hinge area for installation. With the metal panel out we started removing the two 10 millimeter bolts to the right of the trunk hinge. These would be the mounting points for the new trunk lift kit bracket. With everything clear, it was time to start assembling the kit. We secured one side of the strut with the longer ball joint stud to the metal bracket along with the plastic spacer to separate it from the bracket and tighten the hardware.

Now it was time to remove the torsion springs. These are the original rods that hold up our Miata's trunk lid. Using a screwdriver we carefully pry each spring out of the notch on each side that keeps them secure, being extra careful to slowly release tension so they wouldn't go flying out. With the torsion springs out, our original bungee cord couldn't support the weight of the trunk lid so we had to add a second one for more support. Now we could start installing the bracket. First we secured the bracket with the bracket spacer in the now open bolt holes in the back of the trunk, slipping it up and over the fuel filler neck. When the torsion springs were removed there was a hook mounted to the side of the trunk lid hinge. Based on the kit instructions, aligning the hook to the hinge allowed us to mark the center of the hinge for drilling using an orange paint pen. Once the center was marked, a couple punches with the tap and we were ready for drilling.

First we drilled into the hinge using a 1/8 inch drill bit. Then we enlarge the hole in the trunk with a 5/16 inch bit. After a quick vacuum to remove the metal shavings we were ready to install the other side of the trunk lift strut. Lowering the trunk lid slightly, we installed the ball stud into the newly drilled hole. Then we began tightening the lock washer and nut on the opposite side of the trunk hinge. I used one finger to apply pressure to the nut while tightening down on the ball stud. To tighten it down with limited access due to the hinge flange I found it easiest to get the open end wrench parallel to the ball stud and lock onto the nut from that position. Then I tightened using another open end wrench on the ball stud itself.

With the lift kit in place we tested to see how it performed, and it worked great. The trunk came up smoothly all on its own. The last step was to put everything back together, installing the rear metal panel covering the fuel filler, the trunk trim pieces, the carpeting, and storage.

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