I am also curious about this - I just did my rear brakes (rotors, pads and parking brake shoes) and I noticed the rubber seal on one of the inner pistons was worn out. The piston (or puck) itself is still fine and I tested the operation of it and it works ok. It seems that only the rubber seal has worn out.
Rather than replace the entire caliper ($150) I am looking at this kit as well. As far as I can tell, only the seal requires replacement and this is what this kit ($30) is apparently for.
Is this job difficult? It looks quite straightforward...I don't think replacing a rubber seal qualifies as rebuilding a caliper...am I wrong? Thanks...
2007 E550 4Matic - 61,000 Km - Iridium Silver, black leather, Sport package, Premium 2 package
2007 GL450 4Matic - 62,000 Km - Obsidian Black Metallic, black leather, all options
1998 E430 - sold
1989 300E - 333,000 Km - sold
1977 280E - sold
1971 250 - retired
"And a frign hat. They gave me a hat at the annual benefits meeting. I said. how does this benefit me. I dont have anything from the company.. So they gave me a hat." - TheDon