Model A

Ford Garage

Reproduction Stainless Steel Mufflers

Pictured above is a failed stainless steel reproduction muffler, and a new replacement one showing the weld construction before cracking.

Thanks to Mike Keating for his permission to share his photo and story below on Ford Garage:

This failure occurred after about 3000 miles with a slip fit clamp, not a padded clamp, but I did set the clamp with a small stack of S.A.E. washers as spacers between the ends so the pipe could twist and move a bit while making the manifold clamp connection.

The new replacement next to it also has the same poor design that necks in next to the weld point. Compare that joint to the picture of the NOS muffler on Marco's roadster.

My broken muffler looks a bit different in finish (to the new replacement) because I didn't like the polished finish, so I spent an hour on it with a red Scotch-Brite pad.

One additional point about overall weld quality - if you examine the weld joining the muffler body to the end bell, about 1/2 inch below the longitudinal body weld, you will see a small leak spot where the edge of the bell is exposed, not attached to the bead. The welder missed, and laid the bead on the body only!

There is likely more to it than just the slight difference in thermal expansion between a plain steel and a SS muffler. I believe the SS version cracks easier because the grain structure is adversely affected at the non-annealed factory weld. As a result it takes less cyclic flexion to work harden and crack than the plain steel job.

Mike Keating
March 2010

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