ohiorider
New member
My 1991 GS is a 150,000 mile machine. It recently developed a pulsing front brake when it was applied. So, I took the following steps.
- mic'd the rotor and found it was below thickness spec, but thickness was consistent throughout rotation.
- used a dial indicator (mounted to fork) to check for run-out. It was .002" total, or .001" in each direction.
- I noticed that for about 90 degrees, the brake pad(s) would drag. For the remainder of rotation, it rotated freely.
Neither run out or thickness seemed too far off, but not believing my readings, and having a preconceived notion that the rotor was causing the problem, (it had 90,000 miles on it) I ordered the appropriate EBC rotor, and mounted it. Also installed a set of aftermarket 'all balls' front wheel bearings to eliminate them as a source of the problem. I snugged the axle nut and caliper bolts to a high enough torque reading that they were well in place. New pads haven't arrived yet, so I tested with the old pads by slowly turning the wheel by hand with it elevated off the floor.
The front brake continued to drag same as before when wheel was turned through approx. 90 degrees of rotation. For the remaining 270 degrees or so, no dragging. Same problem, but now with new rotor and wheel bearings. I marked the rotor with chalk to confirm that the dragging was taking place at the same place each wheel revolution. It was.
I'm at a loss. Your thoughts would be appreciated.
Ohiorider
- mic'd the rotor and found it was below thickness spec, but thickness was consistent throughout rotation.
- used a dial indicator (mounted to fork) to check for run-out. It was .002" total, or .001" in each direction.
- I noticed that for about 90 degrees, the brake pad(s) would drag. For the remainder of rotation, it rotated freely.
Neither run out or thickness seemed too far off, but not believing my readings, and having a preconceived notion that the rotor was causing the problem, (it had 90,000 miles on it) I ordered the appropriate EBC rotor, and mounted it. Also installed a set of aftermarket 'all balls' front wheel bearings to eliminate them as a source of the problem. I snugged the axle nut and caliper bolts to a high enough torque reading that they were well in place. New pads haven't arrived yet, so I tested with the old pads by slowly turning the wheel by hand with it elevated off the floor.
The front brake continued to drag same as before when wheel was turned through approx. 90 degrees of rotation. For the remaining 270 degrees or so, no dragging. Same problem, but now with new rotor and wheel bearings. I marked the rotor with chalk to confirm that the dragging was taking place at the same place each wheel revolution. It was.
I'm at a loss. Your thoughts would be appreciated.
Ohiorider