Why would teeth break off the ABS tone ring in the front hubs? I just removed the front hubs and axles (as one piece) to do u-joints, upper and lower ball joints and axle seals. Put back together and within a few miles of driving started noticing the ABS pump going off at 10mph or less (foot on *or* off the brake). I thought the sensors might not have been seated right but when I saw they were and looked inside the hub this is what I saw. 3 broken teeth on driver side, 1 on passenger side. These hubs have no play in them and were replaced 57k miles ago. Truck doesn't tow or see off-road use.



How does this happen??

I should note that I did NOT beat on the hub at any time during the u-joint work. It was pressed off the spindle using a socket extension and steering pressure and the u-joints were pressed out/in with a ball joint press.

Any advice much appreciated.

 

Did you remove the sensors to take things apart, or unplug them up by the frame. If you removed them, there's a pretty decent chance that some foreign materials got in there, and things went grind/crunch.

 

When you press the hub/bearing assembly out of the knuckle, it's pretty important to leave the shaft nut tight, to hold the bearing together. The only thing I can guess is that the bearing started to come apart while the hub was being removed, then when you retorqued the shaft nut during reassembly, something got crunched when it got pulled back together.