Sources have told _The Weekend West _the gang has quietly engaged in a recruitment drive over recent weeks and has almost 20 members.
It is believed they may have established a new clubhouse in O'Connor.
In August, many of the Rock Machine bikies who had been involved in a violent feud with the Rebels bikie gang either left or were booted out of the gang, leaving only a few members.
At the time, Assistant Police Commissioner Nick Anticich said police intelligence suggested Rock Machine was disintegrating, adding there was "unsubstantiated" intelligence to suggest a sub-group that had left Rock Machine intended to join the Mongols.
He said reports of the Rock Machine woes suggested police efforts to deter their activities were working and were indicative of instability within criminal networks in WA.
A post on the Rock Machine MC Perth Facebook page, placed on January 2, refers to the gang gaining "more loyal brothers".
"Rock Machine MC Perth would like to wish everyone a happy New Year's Eve let's hope 2012 is a bit easier than 2011," the post says.
"We are rapidly growing in Perth and worldwide, our brothers in jail are staying strong and have our support 100 per cent.
"2012 is our year to grow and move forward as we are gaining more loyal brothers and our support continues to grow stronger."
The feud between Rock Machine and Rebels bikies involved a string of tit-for-tat exchanges that included firebombings, bashings and the alleged attempted murder of the Rebels WA president Nick Martin.
It was believed to have been fuelled largely by the defection of a member from the Rebels to the Rock Machine.
Throughout the mid-1990s Rock Machine waged a deadly turf war in Canada involving rocket-propelled grenade attacks and bombings against the world's best-known gang, Hells Angels.
That war led to more than 160 deaths, including an 11-year-old boy who died as a result of a car bombing.