I did search the forum, and couldn't find anything to help.

So, i'm tackling a break job by myself, get into it, and have trouble removing the rear rotors. Not uncommon, so I followed some suggestion to use the screw holes in the rotor to screw a longer screw into the rotor to have it push the rotor off the hub. But after a while I heard something break behind the rotor, and looked to find this ring of big teeth behind the rotor and half of the ring completely broken away from the assembly.
SKANDIX Shop Volvo parts: Sensor ring, ABS 30814718 (1017532)
According to a little googling, its an ABS sensor ring? Is that true? What does it really do? Can i drive the car unrepaired for a while?
Urgent, fast help would be appreciated!

 

The toothed ring is used for the ABS. At some point, its going to trip the ABS light. I think you have to remove the rear hub to replace it. The labor isn't hard but the part is somewhat expensive. Might as well replace the bearng since you'll have it off.

 

Could a salvaged tooth ring in good condition be used from a wrecked vehicle?
I am not sure if this would be a good practice however, especially as it involves your vehicles braking performance.
Possible cost saving if viable.

 

As an update, without the ring on on wheel, the ABS light did turn on immediately. In addition, the traction control/ABS system thinks that all your wheels are spinning too fast since "one isn't spinning at all" - due to no reading on the sensor. So for the first 30-60 seconds of driving the car will try to stop itself.
As a fix, yes I considered getting a salvaged ring, but that entails finding one, and removing two hub/bearings to get it off the old and put it on my car. I didn't think a used part would affect the brake system as the part seems generic.
I may consider it in the future but for the interim here's a description of my quick and dirty fix. I got the ring back on, secured and all, without having to take off the hub!
First, I drilled holes in the ring on either side of each break, so 4 - 1/8" holes.
Second, I soldered some wire through the holes on the piece that would be attached to the hub. Then I attached that piece to the hub.
Third, I threaded the longer ends of the already secured wires through the "loose" piece, and soldered those on. I had hoped that after doing this the "loose" piece would be secured, but i was a little wiggly, and when it passed the magnetic sensor, the sensor would pull "loose" part away from the hub. Since the wire/solder was doing its job holding the pieces together, but not keeping the loose piece from moving, I used good old fashioned glue to attache the loose part of the ring to the hub. So far so good!

I decided to do it this way since I have not had an easy time removing hub/bearings in the past. Maybe volvos are easier? I thought about trying to repair the ring first, but the break in the ring was not clean so super glue and jbweld weren't working. Plus, repairing it first would mean removing the hub to put it back on.
Thanks for your help and suggestions.