How to rebuild my front brake calipers?

[onnaj1000]

Hi,

My girlfriends car has a problem with a stuck or leaking caliper. When she's braking hard the car breaks out a lot to the right. This is really really dangerous. I let a garage check the brake difference both on the front and the back. The difference on the front is 17-29% and on the back only 0-7%. So the problem is in the front.

As far as we can see the left front caliper is leaking. We won't to rebuild this, but we're looking for a good how to on this. Can't imagine this would be a really difficult job.

Can someone help me out? And what is the piston size? She has a car without ABS so i assume it's 48 mm instead of 51 mm?

[AdamB]

Believe the piston size is all the same.

Rebuilding them isn't a terribly difficult job, you just need to make sure that everything is clean when you put it back together because any dirt/grit between the piston and cylinder will wear it out fast.

There isn't a "how to" I don't think, but long story short, caliper off and drain the fluid, use compressed air to push the piston out, remove the dust seal, then the square cut seal and any others behind (if there is any), then clean and rebuild in opposite order.

Be sure to lube everything up in brake fluid when you re-assemble. Also be careful of the square cut seal, they are very easy to tear.

[onnaj1000]

Okay thanks! I bought a second hand caliper today and might rebuild the old one when I have more time :-)

[morgey]

Also use proper brake grease for the sliders. Its silocone based grease if you use any other petroleum based stuff it makes the rubber boots swell and they bind on the sliders.

Its generally straight forward theres only 3 moving parts on the front calipers so not much you can do wrong