Quick question about caliper slider pins. I did some searching but never could find an answer. Parts books and shop manual don't tell me what I'm looking for.

The other day I jacked up all four corners to swap over to winter tires and thought I'd tear apart my brakes, lubricate the slider pins, and otherwise make sure all is well.

I noticed that each caliper has two different types of pins. One is (for the most part) a solid cylindrical shaft, and the other has a cutout with a rubber sleeve.

On each caliper, these are mounted both ways. Two with the rubber sleeve in the upper position, and two with the rubber sleeve pin on the lower. If only one was different, I'd assume that was the wrong one.

Which is correct? I installed them with the sleeved pin on the bottom, thinking that with that slider closer to the ground, it would help keep moisture out.

 

They go on the bottom.
What they are for? Nobody know. For real...
Nobody knows what they are supposed to do.

In my opinion they're like an anti harmonic to keep the brakes from making noises. ???

 

Anti-vibration aid sounds reasonable. I thought it was some sort of rubber seal to keep moisture out of the shaft in case something slipped by the boot.