How to Fix An Exhaust Drone

by Skip Shelton

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Exhaust drone is primarily the result of sound waves traveling through the air and vibration that is transferred through a vehicle's frame, body and components. Exhaust drone vibration may also be a result of sound frequency alignment between the engine and exhaust. When the frequencies are aligned, the result is a pressure wave between the engine and exhaust. Sound waves, transferred sound and sound frequency must be controlled to quiet the exhaust. Exhaust system modifications and the application of sound control material will reduce exhaust drone in your vehicle.

Exhaust System Modifications

Step 1

Install a resonated exhaust tip on the tailpipe. Resonated tips are lined with material that damps sound waves. When exhaust gas passes through the resonated tip, the lining damps the sound produced by the exhaust system by as much as 10 decibels.

Step 2

Replace the muffler. Muffler design and size directly affects the sound profile of the exhaust system. Select a muffler with multiple chambers designed to damp the sound waves. Multiple chamber designs cause sound wave collisions, which reduce the total volume of the exhaust system. Altering the muffler design will also alter the sound frequency of the exhaust system, potentially eliminating resonating pulses in the cabin of the vehicle.

Step 3

Extend the exhaust pipe by 3 to 4 feet. Exhaust drone not related to the volume of the sound output is a result of the sound frequency of the exhaust system. Lengthen the pipes to change the frequency of the sound. When the sound frequencies of the exhaust and engine match, a drone may occur. Altering the frequency of the exhaust will reduce or eliminate exhaust drone.

Step 4

Clamp weights to the exhaust pipes. Exhaust drone can be damped by increasing the density of the material through which the vibration must travel. Clamp solid steel or lead to the exhaust pipe both before and after the muffler. Use ring clamps to secure the weight to the exhaust pipes.

Sound Blocking

Step 1

Install a sound-damping hood liner in the engine compartment. Exhaust sounds produced at the engine and exhaust manifold resonate in the cabin of the vehicle. Hood liners damp the sound output.

Step 2

Install vibration-reducing mats on the bare metal of the vehicle's interior. Constrained layer damping tiles, known as CLD tiles, will reduce the vibration of the metal. The drone of an exhaust system is amplified by vibrating sheet metal. Damped metal will not transfer as much of the vibration to the cabin. Apply CLD tiles to approximately 25 percent of the metal surfaces to ensure sufficient vibration control.

Step 3

Install sound-blocking mats in the interior of the cabin. Remove the interior seating, upholstery and trim. Cover virtually all the surfaces in the interior with sound-blocking mats. Connect the mats with seam tape to reduce sound leakage. Reinstall the trim, upholstery and seating.

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