If a garbage disposal is filled with food garbage it will vibrate under use. That is normal.
But if it vibrates when you turn it on and it is empty, you have a problem either with a broken impeller creating an unbalanced flywheel or with the mounting bolts being too tight.
Checking for a Broken Impeller
- Turn off power to the disposal at the electrical service panel.
- Reach down into the hopper chamber and feel the impellers.
- Check to make sure both are intact and one is not broken.
- If they are OK, then restore power to the disposal at the electrical service panel and proceed to check for excessive mounting bracket tightness.
- If an impeller is broken, replace the garbage disposal unit.
There is a resilient rubber pad in the mounting assembly that is a vibration absorbing interface between the upper mounting ring and the sink. If the bolts are too tight the rubber gasket will not absorb enough vibration.
- To make this repair, try loosening the mounting bolts 1/4 to 1/2 of a turn each and then test the garbage disposal.
- If it continues to vibrate then try loosening the bolts another 1/4 turn.