To add an important note here.
The limits on the controller, are primarily the limits on capacitors, which are labeled, usually. Easy to find, there are several of them.
Unfortunately, a common limit number is 53V. OK for 50.4V but at 54.6 (52V), you are pushing the limit hard.
Also, battery readout, and LVC (low voltage cutoff) will not be correctly functional.
Many newer controllers are programmable for all these functions, with 60V or higher caps.
Motors themselves are pretty much voltage agnostic, up to a point. more volts = more RPM.