How to tell if your brake caliper / piston is knackered?

Kristoph · 30 Jun 2013 at 18:47

Hello,

I've learnt the hard way, it seems my rear offside pads have been rubbing quite heavily prior to me putting my car off the road.

Got it back on the road yesterday and took it for a drive.

First mistake was not checking all the brakes and seeing if the wheels spun freely.

Coming back towards my house I tested the brakes.

This happened:

On closer inspection, the pads were practically metal on metal, and on this side only. (The pads had only been driven on for a few months).

Do you think the piston/caliper could be stuffed? Is there anyway of me finding out? Would winding it in, applying the brakes (with something in there to stop the piston coming out) a few times sort it out?

It looks like the dust cover has been off, possibly the reason for this happening.

Any advice?

rodenal · 30 Jun 2013 at 19:19

I can't quite get my head around what, but something looks seriously wrong with that caliper.

Am I being stupid here, Where is the outer dust cover (or is that what you mean)? you need to clean what you can see of the piston up really and make sure it's not pitted (looks bad from that pic but it might just be dirt/marks), if it is the caliper is basically scrap. On a focus where replacement is cheap anyway.

If you want to check the function, clean it up, wind it in, stick the pads back (as theyre done anyway, alternative some 2X1 or whatever reasonably solid thing you've got to hand) on and press the brake - it won't fire out unless you do a full pedal stand so you should be able to stop it from coming off the thread

Tbh just from looking at that, it looks done - is that brake fluid all over the bottom of the carrier etc?

TaKeN · 30 Jun 2013 at 19:20

Why does your disc have two MASSIVE cracks in it!?

The piston will be in bad shape if the cover has been off it like that for a while. From the photo it seems to have a lot of crud/corrosion on it. You really need to clean it up as best as possible with some WD40 and wire wool.

Kristoph · 30 Jun 2013 at 19:27

rodenal said:
I can't quite get my head around what, but something looks seriously wrong with that caliper.

Am I being stupid here, Where is the outer dust cover (or is that what you mean)? you need to clean what you can see of the piston up really and make sure it's not pitted (looks bad from that pic but it might just be dirt/marks), if it is the caliper is basically scrap. On a focus where replacement is cheap anyway.

If you want to check the function, clean it up, wind it in, stick the pads back (as theyre done anyway, alternative some 2X1 or whatever reasonably solid thing you've got to hand) on and press the brake - it won't fire out unless you do a full pedal stand so you should be able to stop it from coming off the thread

Tbh just from looking at that, it looks done - is that brake fluid all over the bottom of the carrier etc?

The dust cover has come off the lip, and can be put back on. The piston isn't too bad, and is a bit dirty. Thats WD40 from trying to loosen some nuts earlier and also the metal shim that sits the pads in firmly. It was pretty stuck.

TaKeN said:
Why does your disc have two MASSIVE cracks in it!?

The piston will be in bad shape if the cover has been off it like that for a while. From the photo it seems to have a lot of crud/corrosion on it. You really need to clean it up as best as possible with some WD40 and wire wool.

The cracks were caused by driving it with the pads rubbing, and then applying the brakes while they were hot. I've seen a couple threads over on cliosport where similar things have happened. Not good...

Lopéz · 30 Jun 2013 at 19:28

Your caliper doesn't appear to have any seals on the piston and your disc is ever so slightly broken

Zeed · 30 Jun 2013 at 19:31

**** i would get both calipers new discs and pads ofc.
Srs **** this is...

Kristoph · 30 Jun 2013 at 19:37

The seal is there but it's folded on itself.

The discs and pads were changed less than 5,000 miles ago annoyingly!

I'll price up new calipers discs and pads. Expensive week for driving, having just insured and taxed it.

Clarkey · 30 Jun 2013 at 19:38

Was that photo taken straight after? If so, that isn't binding, it isn't working at all!

Jono8 · 30 Jun 2013 at 19:43

Thats broke.

rodenal · 30 Jun 2013 at 19:48

I wouldn't go replacing the other side though (if that's what you're suggesting in the post above) - unless you've inspected it and it's actually got an issue

TaKeN · 30 Jun 2013 at 20:00

Pretty simple really.

1. Both calipers off the rear. Contact brakes international, get yours exhanged for Refurb. Pay moneys.. get new calipers.

2. New discs and pads for rear.

3. Sorted!

rodenal · 30 Jun 2013 at 20:47

There is absolutely no point in replacing the other side unless its suffered a similar fate. Its entirely possible for that caliper to be the only one that's buggered

Housey · 30 Jun 2013 at 20:54

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Good indication too

Kristoph · 30 Jun 2013 at 21:11

The other side is fine, loads of life left in the pad, disc/wheel move freely, the dust cover on the piston is intact.

It's just this one that has seized up. But yes, the other side couldn't be any more fubar.

Fuzz · 30 Jun 2013 at 22:14

Ha, something's not right that's for sure.

If the piston winds in freely then you have some other issue.
Could be the piston, could be the slider, could have been the pads seized into the carrier.
Either way it's FUBAR. Good effort that

the_r_sole · 1 Jul 2013 at 11:08

had a caliper jam on mine before but you could feel/hear it and was replaced with no damage - how the .... did you not notice that?! amazing picture tho, take a bow

Dogbreath · 1 Jul 2013 at 12:05

Are the slider pins jammed? If so then it puts a lot of force into the disc that can cause cracking.

pepsilol · 1 Jul 2013 at 16:10

How can it even get into that scenario within 12 months? ( MOT )

Fireskull · 1 Jul 2013 at 17:08

pepsilol said:
How can it even get into that scenario within 12 months? ( MOT )

In the OP he states its been off the road, no idea how long though...

For the price of a replacement I would just replace it, wonder what condition the sliders are in too!

Kristoph · 1 Jul 2013 at 17:56

the_r_sole said:
had a caliper jam on mine before but you could feel/hear it and was replaced with no damage - how the .... did you not notice that?! amazing picture tho, take a bow

It has to have been rubbing for some time, but before I took it off the road I hadn't heard or felt a single thing - and I'm a fairly paranoid driver when it comes to listening out for odd sounds. I just neglected to check this disc/caliper in the time since I replaced the discs and pads, which was September last year, MOT October, and SORN'd Feb.

Dogbreath said:
Are the slider pins jammed? If so then it puts a lot of force into the disc that can cause cracking.

Will take a look, I've got some brake cleaner and silicone grease, I'll give it all a clean and grease up, wind the piston in and out a few times and see where I am.

pepsilol said:
How can it even get into that scenario within 12 months? ( MOT )

Discs and pads were new September, had an MOT October, and SORN'd Feb. So it's a few thousand miles of driving.