We’ve had this problem after a couple of years running the three pin rotor. Ours broke during a road race. Fortunately we had front brakes and no one was hit by the flying rotor. Your rotor is worn and also broken. Still suggest you upgrade to a six pin unless this is a fun kart.
Hi Steve We have a bunch of brm karts that have that set up and yes you have to watch the fastners for wear. Have found that you can adapt a ven 4 fastner to work. you can also use the rotor and hub for a replacement will work you may have to slightly move caliper. As stated before the 5 pin hub is better and will last a while longer. Hope this will help.
Thanks for the tips guys. It looks like I can buy a brand new brake setup (master cylinder, caliper, rotor and hub) for less than the cost of the VEN04 rotor. I might just do that and throw the rest of this CRG junk in the trash :)