Hi, Hope you are on the road by now. If you are not the two screws inside the relay are machine screws. I went out to look at a spare relay. The screws holding the relay itself down are sheet metal screws. the screws inside actually hold down a large fuse. It seems your troubles may be deeper if whoever is working on your car can't figure this out. Duct tape will hold the thing down to get you home! Was the fuse blown? Does the car start ? Sorry I do notknow the exact size of each screw.Good Luck! I dont like to hear anyone stranded. The screws are metric.