Junkyard War by Faith Hunter

It’s find retribution or die trying in Shining Smith’s ultimate challenge, from the author of the Jane Yellowrock and Soulwood series.

Shining Smith and her crew have obtained the weapons they need to rescue one of their own from the grips of their mortal enemy, Clarisse Warhammer. But to mount an assault on her fortified bunker, they have to cobble together an army of fighters.
That could be the biggest battle of them all.
Shining will need to step back into the biker world she left behind to broker an uneasy peace, then lead rival factions into a certain death trap. Can Shining take Warhammer down without having to compel more and more people to do her bidding? And will her feline warriors, the junkyard cats, remain loyal and fight alongside her? Or will Shining have to become something and someone she hates, so that vengeance can finally be hers?