They break like any other spring.Had one break on my 67 Fury that was like 71.Had another snap on my 66 Imp that was 83.They are a spring plain and simple.Had more than one coil and Tbar brought into the shop.One on my 67 I parked it went out next day and it was snapped sitting in the drive.Why people think they cant break is beyond me.Not as common as coils but they breal like Leaf springs do.Rocky