The felt is there to retain some oil and keep the slides lubricated longer. they are not critical, but helpful. your "FLAPS" or Favorite Local Auto Parts Store should carry small tubs of caliper grease. Or sometimes they have little blister-packs of caliper grease at the counter (A little goes a long way). thick ,usually black, grease. excellent stuff. I use it on all pins and slides for front and rear.