Picked up some AC-Delco gold calipers with pads from RockAuto, was a good deal so I pounced. Got new lines too (cuz why not?). I thought it was interesting that the calipers state that they're the "revised" design. Any idea what changed?

For the inevitable suggestion: no, I'm not throwing them out. Car goes, car stops, I'm not auto x-ing or doing anything insane, happy with the stock performance of the brakes.

 

Front or rear?

For the fronts, I know of no changes to those calipers since their introduction in the late 60s.

Rears however, that may indicate that the "recall kit" was already installed in them.

 

Fronts, that's what I thought too but who knows.

 

Revised design for fronts probably means made in china

 

Nope, Mexico.

I'm thinking it has to be something internal with the piston or something.

 

Possibly...

If so, most likely changing it from aluminum to plastic. Which in some ways, might be an improvement, since plastic at least doesn't corrode.

 

Here is a clue from corvette forum "The new, not rebuilt ACDelco casting being sold today are all SS Lined and I believe they all are the newer design using o-rings and not lip seals."

 

Stuff like this is why I love this forum.

That sounds like a plausible explanation.

 

Some calipers of that style were changed to make the piston retract a little to prevent brake drag as a way to increase fuel mileage. I think the piston seal was different.