[AWM614]

Couple of questions. I am rebuilding both front brake calipers. On the right side the pistons had the cupped side out towards the brake pad, on the left caliper the flat side was out towards the brake pad. Looking at the parts catalog online, I can't really tell which way they should be. I see in a previous post it was said that the cupped side is always out. I am now assuming that an error was made along the way by a prevous owner so am going cup side out on both. Any other opinions?

Also, one pin plug was stripped on the left caliper and the other I had to drill out. I assume those are for keeping dirt out and can be filled with high temp silicone to seal them.

 

[busdriver]

Cupped side should face pads, but there is often a small metal disc that is fitted to the piston hiding the cupped portion behind it. It may have fallen out at some point.
Pin plugs keep the brake pad pins from backing out and should be replaced if damaged.

 

[DriverRider]

The right side was correct someone put the left together bassackward.

Forget the silicone it will make getting in there again difficult and messy for the next guy.

If you got to take short cuts I would put a spot of waterproof grease there to prevent corrosion and limit dirt intake somewhat.