How to Remove Brake Caliper Pistons
Removing brake calliper pistons isn't too hard to do, but the trick is to get yourself organised before you make a start. First of all, buy a proper repair manual for your vehicle's make and model. Next thing, does your car have ABS braking, if so, disconnect the battery before you start. Do not re-connect the battery until you've completely finished working on the brakes.
To remove the front brake pistons, block the rear wheels so that the car won't roll, and put the car into gear as an added precaution. Loosen the front wheel nuts, and then jack up the front of the car. For safety's sake, don't just support the car on a jack, you must use axle stands as well.
Use a brake hose clamp or a molegrip to clamp the brake hose close to the calliper you will be working on. Clean up the calliper hose union, and loosen the union off, then slacken and remove the bolts that hold the calliper in place. Unscrew the calliper from the brake hose, and remove the calliper, this will allow you better access to the piston.
Prise out the piston, dust seal, and finally, but carefully, the piston hydraulic seal. Clean all the components, replace the hydraulic seal with a new one, fit the dust seal and finally push home the piston. You will find that soaking the piston and the hydraulic seal in brake fluid will help the assembly no end.
Pop the calliper back on and tighten up the hose union. Ensure the brake pads are seated properly, and remove the brake hose clamp. You will now need to bleed the system, but if you are doing this job yourself, invest in a proper brake bleeding kit.
This kit has a one-way valve fixed to a tube, the other end of the tube fits over the brake calliper bleed valve. You then open the bleed valve, and pump the brake pedal. Make sure you keep the master cylinder topped up during this, and once all the air is removed, you're done. All you have to do then is re-tighten the bleed valve, check the brake pedal shows normal travel, and check the brake fluid level.
Every car has a different system for changing these pistons, so it's best to check out a proper repair manual for guidance. Some models just require the removal of two bolts, and the brake calliper piston can be removed without disturbing the brake pads. Some others, as I have described above need a bit more dismantling before you can replace the piston.
Whatever your car requires, make sure you follow the manual, and don't bodge it. These are the brakes we're talking about, if they don't work, you may kill yourself, or someone else. So check you've done the job right, then check again.
