Rebuilding Al MC or Calipers often fail after if works now.
May look good but Most times the surface has enough "rust" pitting so new seals fail fast.
Many have enough crap where seals and pistons never touch during normal braking causing failure too like Dead MC after "Pedal Bleeding" because 1 or both pistons hit the crap section(s) in the bore. see
https://web.archive.org/web...ierocave/brakes3.htmYou can't hone them like cast iron parts in many "books."
1. Many Al parts are anodize and honing removes that then the bore "rots" faster.
2. Most brake honing "kits" have wrong stones and eat the Al fast and uneven making problem too.
3. Even some "Scott bright" materials can wreck the bore trying to remove other crap in there. Actual 3M or clone make a lot of different ones w/ or w/o adding extra abrasives to the mix. I mention this because Dremell (and maybe some others) make several "Scott bright" tips under "EZ Lock Abrasive Buff." Dremel "Finishing" buffs (511E) can "grind" hard enough to marks on steel.
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Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)
The Ogre's Fiero Cave