Shyne completely distanced himself from his Diddy past after the Bad Boy mogul got arrested last month ... and it was all one big phony act, according to Funkmaster Flex!!!

The Hot 97 radio vet recently admitted he's been stewing over Shyne's claims that he was the fall guy in the infamous 1999 nightclub shooting that sent him to prison for 8 years, before being deported to Belize.

Shyne is currently promoting his upcoming documentary "The Honorable Shyne" ... but Funk Flex says he's capping, and raked him through the coals on the airwaves!!!

Funk Flex started his newest rant claiming to have love for Shyne but soon burned down his house using plenty of ether ... "I don’t know what people are talking about Shyne was the streets, he was a punk."

"So all of that street talk, you don’t ever come my way with that, Puff had to keep people off of you from beating you to death!!!"

According to Flex's expertise, Shyne pulled out his gun in the nightclub because he was too scared to face the man accosting him and Diddy after the "That's Gangsta" rapper backdoored his company in order to sign with Bad Boy Records.

Flex says Shyne signed with Diddy and immediately was forced to eat a platter of knuckle sandwiches courtesy of Biggie's homeboy Damion “D-Roc” Butler for coming into the fold with his nose up high.

Shyne burst onto the scene in 2000 claiming Brooklyn with a vocal drawl similar to Biggie's, whose death was still lingering in the hip hop community.

"The Honorable Shyne" features Kevin Liles and other execs claiming Shyne was the hottest rapper free agent at the time, but Flex remembers things differently ... he wanted to spit in Shyne's face!!!

He says Diddy BEGGED him to play Shyne's records at first and everyone in the doc felt the same way!!!