Found a number of threads, but thought I would start a new one!

I have ATE calipers on rear of my 85 300D. They were replaced 16 years ago. While in process of replacing discs, pads and parking brake shoes, I noticed that one disc had worn unevenly and that one piston on that side was sticky. Boot had a small split in it, so water/salt may have entered.

Decided to have a shot at rebuilding myself. Watched a few videos, but new job for me. Ordered FTE repair kits.

I removed one caliper. I clamped one side expecting the other side to stop at the clamp. But it came right out (Using air pressure). So now I will probably have to reinstall this piston, put in a spacer and then push the other one out? Does that sound right?

I have inspected the piston and cylinder that is open. I noticed there is a build up of some yellow stuff on the inner cylinder surface. Light rust outside the seal. Will try and clean up with scotch pad or ?? Wonder what caused that yellow deposit? Piston looks good, but has some light rust build up on outside edge where boot attaches.

Some pics.

Piston


Cylinder

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Graham
85 300D,72 350SL, 98 E320, Outback 2.5