Knowledge Base - How To:- Front Brake Caliper Refurbishment

Answer

Disclaimer:
First of all I want you to know that I am not a mechanic and have never had any involvement with braking systems on cars.
I take no responsibility for any damage, harm, injury or death that can occur to you, your car or your drive (or other surroundings) while carrying out this job. Any mistakes made are yours. (But if you have common sense you should be fine - this is a fairly simple job really)
Additionally, I am in no way affiliated with either company mentioned in this article, nor am I an expert in the field of brakes. I'm merely an enthusiast passing on his knowledge...

There is a similar write up available in the MK1 section that contains lots of pictures, even thought the calipers they are working on are a single piston the process is very similar so if you are having trouble understanding then click the link below and you will be able to see what is happening if you read through it and follow the pictures.

MK1 Article

If you are doing this then you will be needing the caliper refurbishment kit from flashmetal or similar place also you may need replacement pistons but that is your choice as usually they are OK.

Things to have before starting the job.
Some mechanical knowledge
Someone to press brake pedal
Caliper refurbishment kit.
Pistons ( optional )
Piece of wood 1-2 inch thick, and 10 inches long.
Correct brake fluid for your car.
Paint stripping gun ( optional )

Once you have these you can begin.

To start you will need to get the car jacked up.
Then undo the caliper as if you are changing the brake pads, remove the brake pads by swinging the metal cradle out from the main part of the caliper then remove the brake pads.
Now you need to undo the 2 retaining bolts that hold the caliper onto the hub ( don't disconnect the brake line just yet). Get your piece of wood and put it in front of the pistons, then get your assistant to slowly press the brake pedal while you hold the wood in place, now you will see the pistons start to move outwards, if only one piston is moving don't worry just make sure the wood stays straight until it gets to the back of the caliper, now the piston is nearly out it should be pushing the wood against the back of the caliper, the other piston should start to move now.
Once both pistons are pushed nearly out you can get the other person to stop pressing the brake pedal and then you can undo the brake line.
Now you can go inside an your assistant can put the kettle on while you carry on.

First thing to do is remove the wood so you can get you mole grips/ pliers onto the piston and give it a wiggle to get it out of the housing, don't use a hammer and chisel to knock it out on the lip that is exposed as you will damage the piston wall and have to get a new one.
Now you will need to remove the rubber seals, making a note of how they fit in place.

If you are doing a complete refurbishment then continue to dismantle the caliper and remove all the rubber seals, pull the sliders away from the piston housing, it may be hard but give it a good pull so the rubber boot snaps, to remove the rubber boots from the sliders.
You will need a hammer and old screw driver to knock out the metal ends that hold the boots in place, you may not be able to see this as they are usually fully of dust but it you look closely you will see that they can be removed, so carefully push the screw driver into the edge of the metal ring a prise it out.

If you want to give the caliper a paint to match your car then before continuing you can soak the caliper in hot soapy water for 5 minutes, then give it a good scrub with an old brush, rinse well with water then use the heat gun to dry off the outside, put the barrel into the hole where the piston goes and let the hot air flow through the chamber until the outside is hot to touch ( the inside MUST be dry completely as any moisture left will contaminate the brake fluid when it is put back on the car and may cause the brakes to not work properly )

If you are just doing the pistons then you can start putting in the rubber seals that are inside the housing where the pistons are, once that is done you will need to put on the rubber boot that stops dust and dirt from getting in between the piston and the housing, the metal wire that holds the rubber boot in place can be a bit awkward to get in place, but persevere because it has to be in place before we can move on.
Once this is done, rub some brake fluid around the piston to help slide it back into place, this can be a bit hard to do but it will go in.
Now the piston is in you will need to put the caliper back together and put it back on the car and bleed the brakes.

If you are going the whole way and refurbishing the complete caliper ( pistons and slides ) put the pistons back in first before you put the slider back onto the cradle and make sure that you have greased up the sliding arms before you put the rubber boots back on.

Good luck.

matz

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Created : 2011-10-06 12:11:59, Last Modified : 2011-10-06 12:11:59

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