Based on your symptoms descriptions,
"For the last 3 years since the tire snow chain incident, my brakes have increasingly done a random strange stuttering followed by what sounds like a spring making a 'boing' sound. The brake pedal gets a bit mushy & stutters/skips, springs back at you & for a few seconds feels like it's not braking."
It indicates an intermittent interruption of the wheel sensing circuit. The sensor seems to freeze the signal resulting in the ABS control unit being made to believe that the wheel is locked when brake pedal is depressed. That would cause the kick back of the pedal and stuttering as the control unit releases line pressure to the wheel and cause the brake to lose its effectiveness.
Prossibl causes are :
1. Sensing circuit fault, could be a internal broken wire that is intermittently causing the circuit to provide a broken circuit reading. Since sensor had been replaced, this can be eliminated. However while testing wiring continuity from sensor to control unit, the wire harness should be tugged lightly to search for internally broken wires.
2. Axle shaft pulser defective. On vehicle visual inspection might not be accurate and it would be advisable to remove and recheck for roundness of the ring. The snapped chain could have caused some damage to the ring or it could be a damaged knuckle or bearing causing the pulser to turn eccentrically.
This would result in uneven pulsing signal.
3. Faulty ABS control. When the sensor was damaged, it could have shorted the control unit circuit. This would require the control unit, which is incorporated into the master pump, to be repaced.
Saturday, March 7th, 2009 AT 10:24 PM