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Brake Fluid Leak and a Caliper Headache

Nothing like discovering a brake fluid puddle the day before your first car meet. Time to rebuild (or replace) a leaking GTI caliper—fast.

Sivert

30 Apr 2025 • 1 min read

I noticed a strange puddle under the car—it wasn’t gas or oil. Turns out, it was brake fluid. One of my rear calipers was leaking, and not just a little. Since GTI calipers are pricey, I first tried a rebuild kit.

Disassembly took some figuring out. The Edition 35 calipers aren’t like others I’ve worked on. The retaining ring design was bizarre—we ended up whacking the back of the caliper with a hammer. Apparently there is no retaining ring, meaning it's fine to remove it this way (or so we thought). before figuring out that all we had to do was twist the brass ring out.

Retaining ring setup unique to Edition 35 — As you can see, there's an edge the bronze retainer hooks onto. All we had to do was twist it clockwise to loosen it.

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We finally removed the piston and replaced the seals... only to find the culprit: a rust path behind the seal.

Time was tight—I had a big group drive the next day. So, off to the auto parts store I went to buy a new caliper.

Crisis (barely) averted.