is there anyway to stop the stock back speakers to stop vibrating so harshly (instead of turning down the bass) its stock in a 86 TA

 

You could buy "Bass Blockers". I bought some from best buy and it blocks the bass. Essentially it is just a capacitor and you hook it inline with the positive speaker wire going to the speaker that you don't want bass to go to. They are like $5-10 each at best buy. If you know which type of capacitor to buy then it will probably be a lot cheaper, but i don't know what values they are.

 

did you make sure that the screws were tight.. also you might want to look into getting some new rear speakers that can handle the bass better.

 

if they are rattling, they could be blown, look at them and make sure the rubber or foam surround is not cracked and torn. Otherwise, either get bass blockers(which are ok) or invest in a new set of speakers.