- Disassemble the caliper completely
- Remove the piston from the caliper
- Remove the big spring from the back of the piston. If you’re having trouble removing the spring, grab the piston in one hand and the spring in the other and rotate the spring counter-clockwise
- You should now have just the piston isolated
- To open up the piston, we will be using a small object to press into the nail sized hole in the front of the piston.
- The key to separating the piston without damaging it is to find/make an object that is
- As close as possible in OD to the ID of that small hole.
- Is flat on the end going into the piston (if it’s pointed like a nail, it will possibly damage the internal piston
- If you have something like this lying around great, if not, a nail that fits the hole as closely as possible and then where the pointed end of the nail is cut flat works well.
- Before disassembling make note of how far the internal piston extends past the back of the caliper. When reassembling, you will need to press it back in and need to get it in about the same as it was. It is about ¼“ but measure yours or disassemble one caliper piston at a time using the other caliper piston as a guide
- Now insert the cutoff nail into the piston face. Place a flat object against the end of the nail head.
- You’ll need a short section of pipe or a receiving tube from a ball joint press for the inner piston to slide into when pressing it out
- Use a press or grab a large clamp gripping on one side of a flat object behind the pipe and the other side the short nail head.
- Slowly and evenly tighten the clamps until the nail starts moving. It’s going to be a bit unstable so it might take a couple tries to get everything moving and stable.
- I typically have one rather short nail that just gets everything moving and then a second longer nail that I finish pressing it out with, as most of the resistance and instability of the clamps is in the first quarter inch.
- There’s a spring inside the piston which will pop everything apart when it starts moving enough. Try not to let everything go flying.
- Once you have the internal piston apart, carefully clean everything and replace the rubber seal with the one included in my kit
- Reassemble with a couple clamps or a press, stopping when the internal piston has moved in enough where it is sticking out in the back as far as you took note of before assembly.
Here’s a full break breakout of how everything fits together. Note the rubber seal’s opening should open toward the spring side (to the left in the image below). The washer with the rollers sits in between the other two flat washers.
The rebuild kit to do a complete caliper rebuild is sold in the online store: