WebreaderShopNewsletterTop dealers & workshops

Workshop for mechanicsDisc brake maintenance

Stefan Frey

 · 31.01.2013

Workshop for mechanics: Disc brake maintenancePhoto: Daniel Simon
Workshop for mechanics: Disc brake maintenance
We show you how to bleed your disc brakes yourself if you lose the pressure point. We also explain how to clean brake pistons, shorten brake lines and change pads.


BLEED THE BRAKES

The brakes are your bike's lifeline. You should therefore service them at regular intervals. If the pressure point wanders or there is air in the system, you need to bleed the brakes. We show you how to do this in our picture gallery using the Shimano XTR as an example. A video on bleeding the Avid Elixir 9 Trail can be found below.

After removing the wheel, push the pads all the way back with a sturdy tyre lever.
Photo: Daniel Simon

CLEAN BRAKE PISTONS

The brake pistons also need a little affection from time to time. With little effort, you can get jammed and dirty pistons moving again.

After bleeding, it is advisable to clean the brake pistons. To do this, remove the spreader block. Use a sturdy tyre lever to press against one of the two pistons and actuate the brake lever until the free-standing piston has moved about two millimetres out of the calliper. If you push the piston out too far, it may fall out of the housing.
Photo: Daniel Simon

CENTRE THE BRAKE PISTON

If the brake piston is not positioned exactly centrally above the brake disc, annoying squealing is inevitable. This ensures peace and quiet while driving.

If the brake calliper sits at an angle, the pads rub against the disc and wear unevenly. The aim is to leave a minimum gap to the pads on both sides of the brake disc. When mounting with the IS2000 standard, you can achieve this with wafer-thin washers, which are included in the scope of delivery of the brake (otherwise available from specialist dealers). Adjustment is much easier with brakes with slotted hole mounting, as the so-called post-mount mounting allows corrections to be made. To do this, loosen the screws for the brake calliper until it can be moved. Now pull the brake lever, the brake automatically aligns itself in the centre of the disc. Continue to hold the brake lever while you carefully tighten the two screws again.
Photo: Daniel Simon

SHORTEN BRAKE LINES

Brake lines that are too long are not only visually unattractive, but can also pose a safety risk. However, the correct length is only a few steps away.

Remove the protective cap to access the fastening screws. Then loosen the fastening screw with an 8 mm open-end spanner.
Photo: Daniel Simon

TIPS FOR THE BRAKE

  1. A line cutter (e.g. Magura) cuts the brake line simply and straight. If necessary, you can also use a cutter.
  2. Never mix the two brake fluids mineral oil and DOT, as this can lead to a loss of brake function! The advantage of DOT is its higher boiling point, while the advantage of mineral oil is that it does not absorb water. Caution: Avid and Formula use DOT, Magura and Shimano use mineral oil!
  3. New brake pads only reach their full performance after a short running-in period. As a guideline: eight to ten full braking applications from approx. 30 km/h to a standstill.

REPLACE WORN PADS, IMPROVE BRAKE PERFORMANCE, ELIMINATE NOISE

Test laboratory manager Hans-Peter Ettenberger explains how you can help yourself. | n.Photo: Daniel SimonTest laboratory manager Hans-Peter Ettenberger explains how you can help yourself. | n.
How do you like this article?

Using the Shimano XT brakes as an example, BIKE lab manager Hans-Peter Ettenberger explains how you can help yourself. You will need these tools: a 5 mm Allen key for the brake calliper; a 3 mm Allen key for the brake pad bolt; a small, firm brush; a flat screwdriver or plastic tyre lever; hydraulic oil and brake cleaner; some fine sandpaper and a clean cloth; flat-nose pliers to help insert the locking pin. You will find the instructions below as a PDF download.

We show you how to bleed a Sram/Avid disc brake here >>

Downloads:

Workshop Brake Service (pdf)

Stefan Frey

Stefan Frey is from Lower Bavaria and loves the mossy, loamy trails of the Bavarian Forest as much as the rugged rock of the Dolomites. For technical descents, he is prepared to tackle almost any ascent - under his own steam. As an accessories specialist, he is the first port of call for questions about equipment and add-on parts, while as head of copywriting he sweeps the language crumbs from the pages of the BIKE print editions.

Home

Most read in category Workshop