Kim Richards: Throwdown With 'Bad Girls Club' Alum ... The Sweaters Come Off!!!

Kim Richards got so riled up during a fight on her new reality show 'The Mother/Daughter Experiment' ... the gloves didn't come off but her sweater did.

TMZ obtained a clip of Kim and former "Bad Girls Club" alum Natalie Nunn getting in each other's faces ... you gotta see it.

Kim seems sober as she tries to protect her daughter, Kimberly, and Shar Jackson's daughter, Cassie, from Natalie's wrath.

You know what they say ... never get between a mama bear and her cub.