How do I repair broken interior plastic pieces on a Mazda RX-7 FB?

Difficulty: Easy to Moderate

Old interior plastics get incredibly brittle, but you don't necessarily have to track down expensive replacement panels. Depending on the type of break on your FB, there are two proven ways to repair them.

As a general rule before starting either method, clean the broken edges thoroughly with isopropyl alcohol. Decades of finger oils and interior protectants (like Armor All) will prevent any glue or cement from biting into the plastic.

Method 1: The "Poor Man's Fiberglass" Patch

This is a favorite community fix for 1st-gen RX-7s. It uses basic household materials to create a reinforced structural patch on the back of the panel and a smooth finish on the front.

1. On the back (non-visible) side of the plastic, hold the broken pieces together and spread super glue over the crack.
2. Tear a strip of toilet paper or paper towel, lay it over the wet glue, and then completely soak the paper with more super glue to create a fibrous reinforcement ¹.
3. On the front (visible) side, fill the crack with epoxy to cover the gap and create a solid surface ¹.
4. Let the repair cure overnight, then carefully sand the epoxy flush using a Dremel and paint the piece to match ¹. Be gentle with the Dremel so you don't burn into the surrounding original plastic.

Method 2: Plastic Cement Welding

If you want to chemically fuse the plastic back together rather than patch it, owners of later-model RX-7s swear by this method, and it translates perfectly to the hard plastics in your FB.

1. Pick up a tube of plastic cement from a hobby or craft store. Unlike super glue, this actually melts the plastic so the two halves fuse together ⁵.
2. Apply a generous amount of the cement to both broken edges.
3. Press the pieces firmly together for about 30 seconds. If you are fixing a larger piece, use small plastic clamps to hold the tension ⁵.
4. Leave the panel alone to dry completely before reinstalling it.

Note on Door Handles: If the broken plastic you are dealing with is specifically the interior door handle (a known weak point on early models like the '79), JB Weld can work as a temporary fix, but the best long-term solution is to source a metal replacement handle from another SA/FB model ².