Sound Source

[ribit]

I have read many articles on the use of sound deading materials and where best to install, But I have not seen the 2 or 3 main noise sources. Has anyone identified these factors such as muffler, transmission, poor fire wall construction material, etc. Hope you can contribute to the main sources for the noise in the models of the xpedition.

 

[JTBarlow]

The most obvious source of all the noise is the engine area. It’s somewhat amplified by all the plastic panels with little to no sound dampening material on them reverberating, and especially amplified on Northstars, which trap the sound inside.

Polaris made a small attempt to address this issue with a thick mat on the upper rear firewall on the XPs, something they couldn’t do on the ADVs.
stopping the plastic panels from vibrating is a big step in reducing noise levels, typically by applying sound dampening material anywhere you can.
Another area is between the floor and skidplate. It’s all open under there, with minimal baffling created by crossmembers, but both sound and heat can travel forward from the engine and add to the sound vibrations from the plastic floor panels.
Blocking off the opening at the rear under-floor area is the next step in reducing noise levels. Since you can’t reasonably apply sound mat to the underside of the floor panels, packing the open areas with insulation can reduce noise by pressing against the panels, reducing vibration, as well as insulating against air incursion.

We’ve been able to get a 7db drop in peak noise levels and 9db drop in average noise levels by combining these two methods.