You use a mould grips or tack weld on a bigger nut. If the nipple is damged hit with hammer to shock the threads. Then if still will not free of cut of nipple head and use a easy out. It should take longer then 15 mins to fix such a slight issue. I do not use the oem calipers we use AP racing on our R1 but I think its a UNF1/4 nipple on the standard twingo. Good Luck.