It sounds like you are describing the accordion-like rubber boots that surrounds the smooth lubricated slide pins to keep out dirt and moisture and they keep the slide pins clean and prevent rust. The rubber TIP I noticed that was missing when I pulled the slide pin out of the slide cavity was the small rubber tip that fits around the machined area at the end of the upper slide pin. In use, the rubber tip is on the end of the slide pin, deep inside the cavity; and, as the brake pad wears, the caliper slides + and - 1/2-inch. And, my assumption is the rubber tip keeps lube around itself as the rubber tip wipes the cavity walls as the caliper slides in and out every time you apply the brakes. For example, why does the lower caliper slide pin not have the rubber tip, if it is needed on the upper slide pin? I did read the post about rear brake noises during braking if the slide pins are reversed. I'm trying to understand the physics of, and the purpose of the rubber tip.
I went to the Advance Auto Parts website and searched for slide pin hardware for a 2011 Compass Latitude, and it pulled up a photo of the Wearever Disc Brake Caliper Guide Pin Boot Kit, Part No. 16109A In the photo are four slide pin boots for both L & R rear, upper and lower slide pins, and the photo shows the two upper slide pin rubber tips.
And, the last person to do a brake job on this car was the technician at the Jeep dealership that was selling this car. This makes me wonder what kind of work they do on their other Jeep brake jobs. Why would he/she remove the rubber tip and reinstall the caliper and slide pin. The slide pin, and brake hose "end" preventing the pin from being removed, had enough rust on it that it looks to be the factory original, not a new slide pin installed when he/she did the brake job, less than 6-monts ago in prepping the car before putting it on the sales lot. Again, what is the purpose of the rubber tip?
15 Jeep GCL; 11 Jeep CL; 67 Jeep M725 Ambulance;
04 Ram 2500 CTD; 46 Willys CJ2A