How to get pads out caliper?

Make a note of where everything goes and pull the caliper off the disk, then the pads should just come out. Take the top off the master cylinder to allow the pistons to retract, because they might need to a bit to get the caliper off especially if the disks are worn and have a bit of a lip on them. And you'll need to retract the pistons a lot further to put the new pads in anyway).

I sometimes push the pads away from the disk a bit with a screwdriver. If possible you can fit it in at the back of the caliper where the metal baseplates of the pads protrude a bit and push them apart.

You often get new shims and clips and springs and things with the new pads.

On some manufacturers the piston does not push back into the housing but winds back. A special tool is required to do this, although a big set of mole grips may work!

It'll usually push back a bit, enough to get the pads out. But then you have to push and twist at the same time, which can be done with a pair of long-nose pliers if you don't have the tool. You open the pliers a bit, put their noses against the protrusions on the front of the cylinder, sort of wrap your hand between the handles of the pliers and push and turn simultaneously while grimacing in pain.

If you put mole-grips around the piston you can turn it, but it's hard to push it at the same time. You have to do both, otherwise it just goes round and round without retracting. You also have to be careful not to damage the rubber boot around the piston with the mole-grips. But if it doesn't turn at all with the pliers, it might be worth just rotating it a bit with the mole-grips to free it up.

This twist-mechanism is found on the rear, and is something to do with the handbrake. I don't really understand how they work though. It's like a sort of rifling of the cylinder, but I don't know if the piston rotates as it emerges under the normal action of the footbrake. If the mechanism really stopped absolutely all retraction without twisting, the brakes would bind on every time you used them.

The difficulty with handbrakes on disks is that you apply the handbrake onto a hot disk after driving, then the disk cools and shrinks away from the pads causing the car to roll off down the hill (with drums, the drum shrinks onto the pads, making the brake tighter). Somehow they've solved this and those twisting pistons may be part of the solution. I still leave my car in gear though.

The last time I did one of these, I couldn't get the piston back far enough, and in desperation started disconnecting the handbrake cable. Then I had another go at the piston and it did seem to go back in more easily. I couldn't say for sure if disconnecting the handbrake really made any difference, but it seemed to. It wasn't mentioned in the manual (not the Haynes, but the CD-ROM workshop manual for the car).

Despite looking into my crystal ball I can't find what make the car or callipers are - or whether they include a handbrake.

Its a nissan bluebird,(front) I managed to prise the old pads out. Now I am having problems fitting the new ones in. It has an anti rattle spring at the top and bottom. No shims were there even though the haynes manal says there should be 3.

I can get one side in with the anti rattle springs there but not the other side. Or I can get them both in without the anti rattle springs. are these essential?

Even with the anti rattle springs removed and both pads fitted, the caliper wont close as the outside pad is too wide. These pads are halfords pads. I watched the mechanic fit them the last time with these pads and I know he had to file them down somehow. Is this a common problem?

Am not sure exactly where I am going wrong. Is it common for halfords pads not to be exactly the same shape/width as nissan pads, and hence the problems of fitting them?

I presume the anti rattle springs are meant to be left in the caliper body before fitting the pads?

What is it with Nissan Bluebird brakes at this time of year? There was a chap in here the other day asking about 'em....

Filing the pads ears/lugs is indeed common (and very easy to do). Or are you say it's the pad itself that's too big?

You might want to give my HowTo a read in case it covers anything you're still unsure of.

If you buy say proper nissan/dealer pads do you not get this filing down problem? Whats the best method to file them down? Surely they should sell them to the precise size needed?

Do the anti rattle clips have to be removed before fitting the pads or do they remain in place? Am having difficulty getting both the new pads in. Not sure where I am going wrong, they are the same size as the old ones as I have compared them.

I have been busy at looking various "how to change your brake pads" site that I can find.

Are the shim essential as they were not there when I took the old pads off.

Thanks for the help. I am sure after I have changed them the first time it will be easier next time.

did you unscrew the top from your brake fluid reservoir?

make sure you don't allow any muck to drop in there though.

How much space do you need in order to get them in with the springs in?

The system may work without them BUT they were fitted for a reason, and any guess at why is only a guess, unless you know.

Did you open the bleed screw while retracting the piston(s)? That should make it easier to retract the piston fully, avoids pushing used brake fluid back into the system and possibly damage to the master cylinder. If you have corrosion on the pistons that could stop them fully retracting and make it more difficult to get new pads in.

Biggles

Where does this come from? There must be a clear route from the reservoir into the 'system' with the master cylinder at rest otherwise the fluid wouldn't get replenished as the pads wear and the pistons move outwards. It has to find its way in via simple gravity. So that passageway allows fluid to be pushed in the reverse direction equally.

Yes, and it's long and tiny.

Brake system pressures are high. Even hand force on the master can generate appreciable pressure. Hand force on a large wheel piston though is much less pressure, so open that nearby bleed nipple and do it the easy way.

It's a small hole on most.

Ever thought of the forces say a warped disc etc causes if you feel pedal kickback because of it? Does that damage the master cylinder too?

Despite changing hundreds of pads I've never felt the need to open a bleed screw - unless doing a fluid change at the same time.

and when you've done that, bleed the system through ensuring you have no airlock in your line. Tighten the nipple when you get your iston as far as in as it'll go and hold it there while you tighten that bleed nipple.

...Where it would have mixed with brake fluid of exactly the same age...