I have a 1997 XJ6 base and replaced all four door speakers due to deteriorated foam cone surrounds.
The Infinity shallow Mount Reference speakers are working fine but, I have a high pitched squeak in the right rear door speaker when going over bumps or playing music . This happens whether the amp. is on or off.
I have tried everything to insure things are tight and grounded but it continues and I just disconnected it as it was driving me bats.
Anyone have an idea how this could happen"?
As info. the aftermarket speakers I installed are 2-way and the original was just a midrange on the base audio system.

 

By disconnecting it do you mean electrically or by removing the speaker from the car ? if it is a physical chafing you can put some silicon spray ( or common bar soap ) on the frames mounting foam is it joins the door card base .