Custom Car Seat From Scratch

In making a reproduction custom car from the 1960s, I needed a totally custom seat for the car. I did some searching for vintage plastic and fiberglass patio chairs thinking that may be what the builder used. No luck. I determined I would have to make the seat from scratch.

DISCLAIMER: this seat is for a custom show car, it isn't intended for daily on-road use.

Tools include

110amp Lincoln wire-feed welder

oxy/acetylene welder for brazing

power hack saw

3/4" rigid conduit bender

4 1/2" angle disk sander/grinder

band saw

table saw

The first step was to determine the dimensions of the seat using historic photos. Once that was determined a plywood cradle was built that had the basic contour of the seat on top and fit the car's interior on the bottom. The first photo shows the resulting cradle sitting in the interior with the beginning of the seat's frame set in place on the cradle.

The outside rim of the seat was formed using rigid steel conduit that was bent to shape using an electrician's bender that I bought on Ebay. The frame was made in several pieces and welded together with the wire feed welder to form the outer seat perimeter. Constant trial fitting to the cradle insured a proper shape.

Once the frame was in place back and bottom mounting brackets were cut from 3/4" square steel tubing and welded to the frame. The welds were made wit the parts still in the wooden cradle. The cradle was eventually discarded so a little scorching by the welder wasn't a problem.

A note on welding. The Lincoln welder can weld with wired that has the flux built in or with solid wire and inert (argon) gas shielding. I like to use the latter for projects like this since it results in a cleaner weld without the flux contamination. Either works OK though.

The final step in forming the basic seat was to weld 1/8" x 1" straps horizontally to the frame sides at about 6" spacing to define the seat bucket. the seat is composed of two main components; this frame and bucket and a separate steel insert on which is applied the pleated panel.

These straps were bent to contain 3 flat arms. Two arms extend from the lowest plane of the seat up to the frame and the ends were brazed there. The middle plane is horizontal and is the width of the center pleated panel plate. 1/8" thick white board was stapled to the cradle between these steel straps to further define that panel shape.

This seat has the space-age head rest so a length of 1 1/2" exhaust tubing was welded to the apex of the seat back as a mount for the headrest. A standard 3/4" steel washer was brazed to this tube to hold the 3/4" bolt that attaches the headrest stand to the seat.

With the skeleton of the seat built it was time to complete the seat. Another of the myriad uses of good old duct tape is that it makes a great mold for fiberglass panels. Duct tape was applied to the frame between the metal slats to support the fiberglass. 3 layers of 'glas mat and resin were applied on top of this mold. Once the 'glas set, the seat was removed from the cradle which was discarded, the duct tape mold was removed, and another layer of 'glas was applied to the back of the seat to capture and enclose the metal straps and make the seat one integral unit.

The outer 3" or 4" wide rim of the seat is upholstered with sponge rubber and smooth vinyl. The center of the seat has a panel with a bunch of 3/4" wide pleats. I made this panel from a piece of 16ga sheet metal cut to the shape of the white board used to define the metal straps in the frame skeleton. This panel bolts to the seat with two 1/4" bolts through each skeleton strap. This makes the panel a solid piece of the seat and also hides the edge of the vinyl upholstery around the perimeter of the insert. I used flange-head specialty bolts that I welded to the panel from the top, these bolts have a very large diameter head that when welded to the panel, are invisible under the upholstery padding.

The seat needed some loops on the underside of the frame to accept hog rings that hold the upholstery to the seat. I made these loops by cutting a row of zig-zag strips from a piece of expanded metal available at a steel supplier and welded these to the frame. In that photo you can also see a few of the center panel mounting bolts extending through the seat steel cross-straps.

I smoothed the top of the seat with a later of Bondo sanded smooth.

The headrest was made from glued up layers of plywood. Total thickness of the piece is about 3 1/2" and is made in two halves. Once the glue was dry, the two halves where screwed together with 4 countersunk drywall screws and the shape rounded with a 4 1/2" angle grinder mounted with a 36 grit sanding disk. This makes clouds of sanding dust sob I used a dust mask but forming the shape is very easy. Note that the plies in the wood allow the shape to be contoured perfectly symmetrical just following the glue lines.

The headrest needed a way to securely attach it to the seat with a slender 3" tall stand. I built the headrest in tow pieces so I could mount a 3/4" hex nit welded to a 3/4" flat washer that was in turn attached in a hole bored in the top half of the wood headrest with short drywall screws. A 3/4" hole was drilled in the bottom half of the wood so a threaded rod can be screwed into the nut after the wood halves are assembled. This is the core of the mounting stand. To make the external part of the stand I used a length of 1" steel electrical conduit with two more 3/4" steel flat washers brazed to the ends. This stand spans the distance between the 3/4" flat washers in the top of the seat and one screwed to the bottom of the wood headrest. the 3/4" threaded rod is screwed into the head rest, passed through the tubular stand, passed through the washer on the seat top then secured with a nut and lock washer from below.

if left like that the headrest could twist on the seat and not be aligned with the body. To index this piece I drilled two randomly spaced 1/4" holes in the matching flat washer rims and brazed short stubs of 1/4" steel rod into the holes in both ends of the stand. Thus when the stand is installed it can only fit one way into the headrest and the seat.

to make an upholstery mounting pad for the front of the headrest I made two matching sheet steel panels. One panel was slightly smaller than the other and was attaché to the wood with drywall screws. The second panel is removable and clips into the mounted panel using spring steel upholstery panel clips.

Finally I sandblasted the tubular stand and covered it with Bondo. The Bondo was shaped with the power disk sander to a pleasant double tapered shape.

The last picture is the completed seat ready for the upholstery.

Folks are asking to see the car that this seat is made for. This car is a reproduction of Ed Roth's 1962 Mysterion show car. Strictly for show, it was a run-away hit on the hot rodding scene. Revell even made a plastic model kit of the car that has been reissued 4 times over the years. Unfortunately the car was so poorly built, Ed got sick of the frame continually breaking that he had it torn up and discarded. I fell in love with it as a kid and it was a bucket-list thing to make this reproduction.