The guy who subs in for Zac Efron's ass has some serious issues with his ex, who says he's harassing and threatening her ... according to legal docs.
Jordan Scott has been Efron's stunt double in "Dirty Grandpa," "Mike and Dave Need Wedding Dates" and "Neighbors 2" -- but his baby mama says he's been total a**hole to her. She filed for a restraining order, saying he's strangled her and broken cell phones so she couldn't call for help. She also claims he's harassed her and her new boyfriend.
According to the docs ... Scott agreed to stay away from her, and only gets supervised visits with their kids. He's also agreed to submit to a substance abuse evaluation, but is not admitting any of the allegations are true.
We reached out to Scott ... he had no comment.