Carbon Fiber sucks for exhausts.

I got the job of re-skinning a cool under-seat exhaust for a Triumph Daytona. The original was nicely built with cast end pieces, but used a carbon fiber shell without any form of heat shielding inside. The carbon can self-destructed in a matter of months. When the carbon can failed, it allowed the baffles to rattle, damaging the cast ends. Or, as they say in NASCAR circles, it wallered out.

The owner attempted to repair the can with JB Weld, and that didn't work too well at all. JB Weld has a pretty decent temperature range -- however, it certainly won't withstand 900-degree exhaust gasses. As you can see, it smeared itself all over the inside of the end cap.

To repair the end caps, I milled a 1/4" thick plate for the baffles, and welded it in place. The shape of the can is a true oval, and quite hard to duplicate. I decided that the way to go would be to produce the oval in 4 pieces -- a tight roll for the sides, and a gentle curve for the faces. Since the faces were produced separately, I could take the opportunity to use a decorative bead. This also has the added benefit of stiffening the finished piece.

Unfortunately, my sheet metal roller is only 12" wide. I had to produce the can in halves and weld it together. A 24" roller is pretty high on my list of tools to build or buy.

When he picked it up, every other sentence out of the owner's mouth was "This is so f**kin' cool!" I always like positive feedback like that from my clients!!

This is why I say carbon fiber sucks for exhaust systems. This isn't even the worst I've ever seen. A small crack will form due to CF's sensitivity to vibration, which then allows hot exhaust gasses to escape. This causes the epoxy matrix to deteriorate, and the crack rapidly expands into a gaping hole.