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Why is my lower caliper guide pin different? How differently does it work from the top one?

Checking the brakes I noticed my top guide pin was all smooth while the lower one had a groove on the end with a rubber jacket around it. Something similar to linked pin.

I’m just curious why so and how does it affect all.

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It looks like it is supposed to be that way, see below. What is that band for? Haven’t a clue, but I’d guess the little black band around the lower one is there to hold it in place better.

At my age I’ve given up trying to understand why things are done a particular way and just do it according to the way it was or what the book says. My GM ones are the same, but I put them back the way they were anyway. I’m sure there are several different designs depending on the application.
There is a rubber piece in the caliper on both of mine and sometimes the rubber comes off with the pin and sometimes it doesn’t. I’ll bet both of yours have the rubber, but one is still in the caliper and the other is fitted on the pin. Nothing to worry about as long as you don’t mix them up.

Most caliper designs I’ve run across now use one pin as a pivot for easier pad servicing. Loosen lower, remove upper and pivot caliper out of the way to access the pads. The lower one is probably the pivot bolt.

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Just theorizing, but I feel the rubber sleeve is probably for use as a vibration dampener to aid in noise reduction.