I'm having break problems with my "86" 300SDL!!!!!! Breaks are going to the floor,but only if I use them a lot (like stopping at a lot of lights) otherwise they are fine. Have no leak in fluid, new rotors and pads. Any suggestions?????????

 

It is also new.

 

Air in the lines ?

 

the symptoms point to master cylinder. maybe its a defective one

 

I have to go along with the master cylinder too. Just because it's new dosen't mean it's any good