The Sound of Sidepipes

[Joe C.]

When I restored my Corvette, I installed a brand new pair of GM sidepipes, which were "still in the wrappers" and came with the car when I bought it. Now, 1000 miles later, I notice a rattling sound which comes-and-goes. It sounds like detonation, and I only hear it at highway speeds, and only when it is reflected back to my ears either by underpasses or neighboring traffic.
Are the perforated pipe baffles noted for rattling, or should I check for other causes.

Joe

[Jack H.]

Re: The Sound of Sidepipes

There's nothing in the pipes to rattle (you mention baffles)... The 'baffles' are the periodic mandrel bends (circular indentations) along the side of the pipe. If the engine end of the pipe didn't bend, you'd see daylight by looking through it.

Things that can develop rattles include:

(1) Loose hanger hardware either at the front or rear mounting points.

(2) The side covers, typically from heat shield insulation letting go.

(3) Loose or improperly installed J-clips and hardware associated with the 'shortie' side exhaust rocker moldings.

(4) Loose pipe to exhaust manifold hardware.