How were regular -er verbs pronounced in the infinitive before the final R became silent?

Question

Simple words like parler, aller, monter...how were they pronounced before the final R became silent? And when did the ending become silent, anyway?

Answer 1

They were pronounced with a "soft r", [parleɾ], [aleɾ], [mɔ̃nteɾ] vs the current [parle], [ale], [mɔ̃te].

The ending [ɾ] fade out between the 16th and the 17th century.

All infinitives in -r were affected, so verbs like partir were pronounced [parti]. The final r pronunciation was restored for all verbs but the first group ones starting from 1750, but that r was a strong one [r].

Sources:

http://monsu.desiderio.free.fr/curiosites/r-phono.html

http://ycmorin.net/wp-content/uploads/2012/11/2012ms-R_final_XVIe_siecle.pdf

http://ycmorin.net/wp-content/uploads/2012/11/2006-Histoire_phonologie_graphie_du_fran%C3%A7ais.pdf