Changing SPI parameters on the fly to suit different peripherals? (AndersG)

Assuming PIC 24FJ64GA004 What is the proper way to do this. I have a vague recollection of being able to do this on the fly in the past, but now changing SPI1CON1bits.MODE16 does not seem to "bite" unless I do: _SPIEN = 0;
SPI1CON1bits.MODE16 = 0; /..