1914 Cadillac Muffler

The following is a recent project that I just completed, the fabrication of a reproduction 1914 Cadillac muffler. It's essentially a composition of sheet metal cones with cast iron fitting riveted to both ends. The original muffler that was provided was in pretty poor condition, but had all of the necessary bits and pieces to make patterns from. The cast iron ends were provided as rough castings that I machined. The inner cones, of which there are four each have steeper angles and allow them to nest into one another. They each have a patterned series of small holes drilled into them to allow the exhaust gasses to pass and to muffle the sound. These were simple to make, the problem came when making the new outer cones. The outer shell has no error allowance and so they need to be exact so both halves fit together and the tapered ends fit correctly into the end castings.

Each outer cone is made from flat sheet metal rolled into a cone. Patterns taken from the original muffler provided the detailed information for making jigs for the Plasma Cutter to cut the semi circle parts. Once cut to length, which included the allowance for the flanges, the lock-seam fold locations were marked using a prick-punch. A set of step roller were mounted to the bead roller and the first seam was made. The next step was to fold the "Lock" portion of the seam using a finger brake. The part was then put into the slip-roll and the cone formed. The lock seam was then mated and locked together.

The next step involved making a set of forming dies for the Pullmax to create the rolled flange in the part that ultimately holds all of the muffler parts together when closed. The first die was good, but went through several modifications to provide a perfectly smooth and unblemished rolled flange. Only one outer cone has a rolled flange, all of the other inner/outer cones just have a simple 3/8" wide flat flange that were formed in the bead roller. The lock seams of both outer cones are also secured with three tapered rivets countersunk into the cones.

Once all of the parts were made the end casting pieces were machined to accept the inlet and outlet pipes, the curf cut for the clamping/cinching bolt and then the bolt holes drilled. Once the machining process was completed, the castings where clamped to their respective cones and the rivet holes drilled. Dome-headed rivets were used to secure each casting.

The final step was to mate everything together to create the finished muffler. The inner cones were all stacked into place onto the outer cone with the rolled flange with the seams all staggered. the second outer cone was then fitted on top of the previously mentioned inner cones and the closing of the rolled flange began. A plastic mallet and block of hard maple was then used to close the flange/seam.

This was a very interesting project and all together took far longer than originally anticipated. Being a perfectionist the muffler had to look as if it were just pulled of the Cadillac assembly line so there was a lot of trial and error to get to the finished part.