DIY: Brake Caliper Repair

Required tools & material:

  • Repair set (gaskets, dust protection, brake piston grease)
  • Brake piston pliers
  • gloves
  • aluminium sealing rings
  • brake fluid
  • brake cleaner
  • Bleed the hose for braking
  • Torque wrench (approx. 5-30Nm)
  • Ratchet set/fork wrench set/screwdriver
  • dental tool

I also used the Stahlbus vent screws with valve – clear recommendation. More about this later…

Disassembly of brake calliper

Since the brake fluid is aggressive, the work should be carried out with a glove. As long as the brake calliper is screwed on, all necessary screws can be loosened. In my case these were: hollow screw of the brake line, brake lining pin, vent screw. Then the brake calliper can be removed completely. One should underlay something, the brake fluid can still run something from the line…

Disassembling the brake calliper:

The removed brake calliper can now be disassembled into its line. I did not open the two brake calliper halves – because in my case there was no reason to do so.

All parts should be sorted so that they can be reassembled in the same order at the end. Also, the brake pads should be installed exactly as they were removed. because they are ground in with the brake disc – so sort everything well.

The brake pistons can now be pulled out of the saddle with the brake piston calliper. That went with me somewhat severely and laboriously, but with something patience, it goes. Make sure that they are pulled out of the saddle parallel and without force.

The seals and dust caps can then be pulled out with the dentist’s tool or with a small screwdriver. Take care not to scratch the brake calliper.

Cleaning and checking

Next, the dismantled parts are cleaned. I used brake cleaner for this. Make sure that the sealing surfaces and sliding surfaces of the pistons are all clean.

Check the removed brake pistons for damage and polish them to a high gloss if necessary. (Was not necessary in my case). If planned, it is now advisable to exchange the brake pistons for others (titanium?).

Before installation makes sure that there are no residues of water/brake cleaner left -> blow out with a compressor.

Installation

Before installing check if the gasket set fits the pistons (unfortunately I ordered the wrong one because there is a difference in the pistons with or without ABS).

First, the seals are lubricated with the enclosed grease. Then press the fingers back into their seat in the saddle. Make sure that the gasket is not damaged! The dust cap can then be inserted. Also, grease lightly beforehand.

As soon as this is done, the brake piston can be inserted with the closed side inwards (in the direction of brake fluid). The open side points in the direction of the brake lining. The piston becomes outside on the surface, where the seal lies also again easily greased. The rest does not have to be greased – otherwise only the dirt will stick better later.

The brake pistons go in with light pressure from the finger – no force!

Check the brake pad pin: This should not have any depressions in the brake pads. I usually clamp them into the drill and polish them with sleeping fleece. Then they are lubricated with ! little! copper paste on the running surface for the pads. The pads themselves are also lubricated with a light film of copper paste on the contact surfaces to the saddle. Only a thin film – otherwise you have the on the rim, on the tire and the brake disc!

Now insert the bleed screw again with the correct torque, check the brake pads and install – tighten the brake pad pin also with the correct torque (if not otherwise secured – e.g. with split pins). Screw on the mudguard.

Replace the aluminium sealing rings on the banjo bolt with new ones and tighten to the specified torque.

Now screw the brake callipers to the fork again with a drop of screw lock.

Next, the brake callipers must be thoroughly vetted and checked for leaks.

As soon as everything is ready, tighten the brake lever with a cable tie (wrap something around the handle so that it doesn’t get an impression). After a few hours (preferably overnight) check that the pressure has been maintained and that everything has remained dry.

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