what does this wrapped thing on middle of axle do?

[callphy]

the one on my passenger side torn apart and rusted below the rubber.

 

[brandini]

Torque damper to make it absorb vibrations.

 

[callphy]

if the rubber is completed gone and rusted blow, should i consider replacing the axle /both axles?

 

[brandini]

I wouldn't worry about it unless you're getting weird vibrations.

 

[callphy]

i do have vibrations coming from my engine bay while idling (but that was partly because the stiff engine mount i use)

checked the wheels, they shakes during idling too