IS200 Front Brake refurbishment

Fozzy
Posting Freak

1,132

26-05-2017, 07:31 AM

Im sure everyone knows how to remove the calliper from the car so im not going to explain that one for you.

I’m going to jump straight in here with removal of the pistons from the calliper body. I have access to an air compressor, which makes this a lot easier. If you don’t have access to compressed air then you will have to get the pistons most of the way out while the calliper is still bolted to the car. To do this remove the pads, and reattach the calliper back onto the car. Have someone VERY GENTLY press on the brake pedal. The pistons will start to come out of the calliper body. Note, you don’t want them to come all the way out, or you will have fluid pouring out everywhere. Once both pistons are almost all the way out, clamp the brake hose and remove the calliper. The pistons should be able to be removed by hand at this point. If you do have a compressor, use a small air gun to blow air through the brake hose hole. Make sure you have the pressure set low, i.e. 25PSI. I used a block of wood fitted where the pads and disc would be to stop the pistons coming all the way out. If one piston is stuck in place and one pops out of the body, it will be very difficult to get the seized piston out.

With the pistons out the way you need to remove the old seals. On the outer dust seal, dig around with a flat head screwdriver and you will find the retaining clip, this can simply be popped out, and the old seal removed.

If you look down the bore you will be able to see the main piston seal. Very carefully prise this out, making sure you don’t score or mark the bores.

Once you have the callipers stripped down completely, it is the best time to clean and repaint the callipers.

Check the bores and pistons for any corrosion or imperfections. If there are any, gently sand them out using 800 grit wet & dry, lubricated with a small amount of fresh brake fluid.

REBUILD

Take your nice clean calliper body and sit on a clean surface. You want to make sure everything is spotless during the rebuild, as any grit in there will damage the new seals pretty quickly.

[Image: IMG_0289.jpg]

Piston Seal fitting:

Smear a small amount of fresh brake fluid into the bore and all over the new seal. Insert the new seal into the bore and get it sitting correctly in one place, then work round until the seal is sitting in its recess.

[Image: IMG_0291.jpg]

Dust seal / Piston fitting:

Make sure the piston is nice and clean.

[Image: IMG_0290.jpg]

Take the new dust seal and smear the inside face with fresh brake fluid. Also smear the outside of the piston with fresh fluid, and slide the dust seal over the end of the piston. Note that the dust seal must be fitted the correct way round. The view below shows the basic profile of the seal mounted on the piston. Make sure you seal is this way round or the metal ring will not fit in place

[Image: dustsealslice.jpg]

Smear some more fluid around the bore in the calliper body. Carefully align the piston with the bore and slide it in. It should go in smoothly. It will get tighter as it slides over the seal, but it should be possible to fit them by hand. If they are too tight then there is a problem with the pistons or bore, so check them for any imperfections. If there is any corrosion, gently sand it off with 800 grit wet and dry and try again.

[Image: IMG_0299.jpg]

Push the piston about halfway into the bore, so you can still access the dust seal recess. Press the seal down into the groove, working around the seal until the whole lip is sitting nicely in the recess. This can be very fiddly and time consuming, as the seal will keep trying to pop out while you are working round. I used a small flat head screwdriver to help coax it into position, but if you do this, be very careful not to slip and split the new seal.

[Image: IMG_0302.jpg]

To put in the retaining clip, hold it between your thumb and index finger, so that the split in the clip is closest to your wrist. Squeeze the clip together, and place the back end of the clip at the back of the piston, making sure it sits down pushing the seal into the groove. Its best to start at the back, as access is quite tight. Once the back is in, lower the ring down so it is sitting as low as you can get it. This whole time continue squeezing the clip and holding it in place with 1 hand. Using a flat head screwdriver, start to feed one side down into the groove. Once one side is in place, make sure it is pushed as far into the groove as it can go. Then carefully work round the other side until the clip is completely in place.

[Image: IMG_0305.jpg]

This is difficult to describe, and as it is such a fiddly job, also difficult to photograph. Once you have the parts in front of you it will become a bit clearer as to how it goes together. You will find that the spring clip will keep trying to ‘ping’ out. Make sure you keep it tightly squeezed together the whole time.

I will try to get a video of how the spring fits to make this a bit clearer.

Alternatively I will be starting to refurbish callipers later this summer, working on an exchange basis for those who are not so confident doing it themselves.

Edited 07-07-2010, 05:34 PM by Rabster.

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