Installing New Pads Without Lubrication

[BMW_E53]

Well the pads and rotors were original with 82k miles on them. The driver's side was pretty low but the passenger side ruined the back of the rotor. (literally there was no pad left) Also @JCL what do you mean by slides hung up?

[JCL]

When you release the brakes, the pads have to be able to retract. They are essentially pushed back away by the run out on the rotor. There are several points of relative motion required for that to happen.

1) The pads have to be able to slide relative to the caliper that holds them in place. That is at the pad ears and around the edge of the pad.
2) The caliper has to be able to slide relative to the caliper support. It slides on those two slide pins that we discussed. This is necessary because there is only one piston, located on one side of the disk
3) The piston has to be able to retract into the caliper. This can be obstructed by corrosion behind the piston. When moisture collects in the hydraulic system, it goes to the lowest point. That is right behind the caliper piston. It can then corrode the piston bore. That can cause the piston to hang up.

If one side is significantly more worn than the other, I would check for all of the above. You should be cleaning 1 and 2 up when changing pads anyway. If the two sides are close, but one pad is slightly more worn, I would expect it to be on the curb side. As RFaber notes above, grit on the road tends to collect on that side, and can cause more relative pad wear than the off curb side.

[BMW_E53]

Well in this situation the piston side wore out the most while the curb side was pretty worn out as well...almost exactly the same. I will post pics later.

[JCL]

By curb side I meant the right side of the vehicle on a LHD car, not the pad opposite the piston. I should have said "if one set of pads is more worn..."

[BMW_E53]

Oh I getcha now.