How to rebuild and widen a fiberglass seat

Update by Tim Suddard to the Elva Mk VI project car
Aug 5, 2024 | Restoration, Fiberglass, Elva Mk VI

Photography by Tim Suddard

Before we could build a roll cage for our Elva Sports Racer, we would need to repair and, in order to fit our primary driver, widen the original seat that came with the car.

While fiberglass seats are not the safest and have gone out of vogue in modern race cars, they are legal by SVRA rules. These rules do prohibit seats made primarily from plastic, PVC, ABS or other similar polymers.

As we are seeking SVRA Gold certification and prepping for concours events as well, we are trying to keep everything in the car as close to original as we can.

While this time around we are working primarily to make the seat functional, we will come back later and make it a bit stronger, wrapping it in either heavier fiberglass or, preferably, Kevlar.

The first thing we had to do was to repair our battered but original seat. It had been cracked and had a hole cut out in the back.

We stripped the covering and padding off the seat and saved it to use as a pattern later.

We then ground down the edges of the area we were patching and, using metal tape, we taped up the hole in the seat. We then cut the seat in half vertically and, using self-tapping sheet metal screws and scraps of aluminum, we added an inch down the center for our plus-sized driver. (In his defense, no one older than 12 years old could have fit in that original seat!)

We then patched the hole using cut strips of fiberglass matte mixed with hardener and resin. Once we got the top and bottom fixed, we removed the aluminum bracing and glassed in the rest of the seat.

At the same time, we remade the flimsy original seat mount out of much stronger steel. Sure, we might have added a little weight, but in the name of safety, it was worth it.

The original seat mount (top) compared to the new one we fitted (bottom)

We then glassed this new seat mount into the inside of the seat for improved strength.

With everything glassed in, including the threaded rod that was used to mount the bottom of the seat, we then ground down the edges and rough fiberglass spots so we could test the seat.