We at the Bakerloo Line have been subjected to ear splitting excess wheel screech for the past 4 months. Originally drivers were told to wear their ear defenders. These would be the ones SQE told us we don't need. The ones that are no longer part of our PPE. We have asked for a local investigation into the root cause of the problems. Surprisingly our PM turned this down!! It is now time to up the ante. T/Ops are advised to ask for the units with wheel screech to be changed over immediately, if Control / DMT are unwilling or unable to do this drivers should look to invoke their health, safety & welfare rights by refusing to continue to drive these trains with known defects. It is not our fault the fleet blame the track and visa versa. We just want all our trains to behave in the same manner. Not too much to ask for or expect is it?