Seized calipers?

[Bobton125]

If the pads on one caliper don’t squeeze against the disc when the pedal has been pushed, is this an indication that the piston has seized?

Ps. There is no brake servo And The fluid has been bled

[sunbeam alpine]

It sounds quite possible. What you can try is to remove the brake pad on the side of the piston (leaving the brake pad on the other side in place). Then use a crowbar to apply pressure to the piston - it should free up. Be careful not to damage the rubber seals!

Has the car been parked up for a while? (Maybe a silly question under the current circs...)

[GreenV8S]

It depends on the design of the caliper. Does it have pistons on both sides, or only one side? It's common for production cars to have floating calipers with pistons on one side only, and the caliper is mounted on sliders which allow it to move sideways to balance the forces on both side of the brake disc. The sliders can wear and jam, resulting uneven braking pressure.

[Bobton125]

The car has been parked up a while yes.

It seems to not have any rubber cover or seal over the piston.

Also I put a socket over the top of the piston and tried compressing with a G clamp. It went down about 1cm. But it was when refitting it, I really had to stamp on the brakes for it to move back towards the disc again. It was like there was no pressure in the caliper

[Bobton125]

GreenV8S said:

It depends on the design of the caliper. Does it have pistons on both sides, or only one side? It's common for production cars to have floating calipers with pistons on one side only, and the caliper is mounted on sliders which allow it to move sideways to balance the forces on both side of the brake disc. The sliders can wear and jam, resulting uneven braking pressure.

It’s just a single piston

[GreenV8S]

Bobton125 said:

I really had to stamp on the brakes for it to move back towards the disc again. It was like there was no pressure in the caliper

That doesn't sound right. Are you familiar with how the brake pedal normally feels on this car? Not having a servo suggests it's something unusual and may feel very different to a modern production car.

[Bobton125]

GreenV8S said:

Bobton125 said:

I really had to stamp on the brakes for it to move back towards the disc again. It was like there was no pressure in the caliper

That doesn't sound right. Are you familiar with how the brake pedal normally feels on this car? Not having a servo suggests it's something unusual and may feel very different to a modern production car.

The brake pedal feels quite firm. Not spongey or anything.

[stevieturbo]

Well if it's apart and you can see/feel it....should be very easy to determine if something is seized or stuck by looking at it ?

[Bobton125]

I’ve never actually come across a seized caliper before, so wanted to make sure that’s what it sounds like before biting the bullet and buying a new caliper.

I thought with a seized caliper, the piston wouldn’t move at all? It moved eventually though just very slowly with no pressure

[stevieturbo]

Pretty much anything that has the ability to move, has an ability to seize. Especially when corrosion is at play.

Look at it and see what is or isnt.

[GreenV8S]

Bobton125 said:

I thought with a seized caliper, the piston wouldn’t move at all? It moved eventually though just very slowly with no pressure

A piston may seize gradually with friction increasing over time rather than suddenly welding itself to the caliper. In that case you'd expect to find that you need a certain amount of pedal pressure to overcome the friction before the brakes start to apply, and probably a similar amount of friction would hold the brakes on a little until bearing flex knocked the pads back. From your description I guess the friction is quite high now. It may be that if you dismantle the caliper now you'll be amazed that it worked at all.

[Niglebick]

sounds like the flexi has died internally. a cheap/simple fix

[danashby]

Bobton125 said:

The car has been parked up a while yes.

It seems to not have any rubber cover or seal over the piston.

Also I put a socket over the top of the piston and tried compressing with a G clamp. It went down about 1cm. But it was when refitting it, I really had to stamp on the brakes for it to move back towards the disc again. It was like there was no pressure in the caliper

Same thing happened in my gf's Focus CC. No point of fixing/replacing the piston on old caliper, better replace the whole caliper.