Serial console changes parameters when SUDOing

I'm working on a project where I need to connect a very old serial terminal to a linux device (a Raspberry). The terminal uses 4800bps, 7 data bits and even parity. I have reconfigured the kernel command line to use these parameters and also the serial-getty service and I get a nice connection where I can login and use the system. The problem comes whenever I use a command with sudo, all the data received by the terminal is garbage, it seems that the system is using different serial parameters when I use sudo, after the command ends the parameters seem to be restored again and continues working as expected... How can I prevent these changes?