FAO CS Mechy's - Is it possible for the rear caliper piston to come all the way out ?

[D1CKY]

This afternoon i was pulling away in my car and it sounded like the rear brakes were slightly scuffing when i applied the brakes it went away.

So i thought nothing of it and drove on as the brakes were free and not heating up(wet finger to check) etc etc, then clunk something hits the underneath of the car.

So i stop and there is the brake lining lying on the road from one of my inner rear pads (as both outer pads still, had linings there).
It had parted itself from the backplate which is still in the caliper as we speak (Aint had time to remove it).
What the f**k would cause my pads lining to shear from its back plate as they were only fitted in September and there more than half the pad left ?

Manufacturing fault ?


Needless to say i drove the 5 minutes to get my car home and investigate.

Now i have a brake fluid leak from the rear drivers caliper as my wheel is covered in it.
And its that caliper that lost its inner pad lining.

Why would i have a leak ?

As the hard brake pipe going into the caliper body is fine and as is the bleed nipple and theres no leaks.

Could the caliper piston have wound itself all the way out ?
And the fluid is leaking past the seal ?

If so are these pistons easy enough to wind back in once they've popped out ?


And if i have to bleed them, how simple is it to bleed brakes on a ABS equipped 172 ?
As i have heard the ABS unit can hold air

 

[sideways danny]

Re: FAO CS Mechy's - Is it possible for the rear caliper piston to come all the way o

sounds like the caliper has seized, cooked the pad by being on all the time, and then fallen apart. Might be ok, but sounds like new caliper time

 

[D1CKY]

Re: FAO CS Mechy's - Is it possible for the rear caliper piston to come all the way o

sounds like the caliper has seized, cooked the pad by being on all the time, and then fallen apart. Might be ok, but sounds like new caliper time

If the caliper was seized the piston would still be in place wouldn't it ?
Therefore no fluid leak ?
As it wouldn't move to take up free space..

 

[D1CKY]

Re: FAO CS Mechy's - Is it possible for the rear caliper piston to come all the way o

Problem solved

I removed the pads from the offending caliper and found the piston had wound itself out a fair bit and twisted the piston seal in the process causing a leak.
So i wound it back in with a screwdriver with very little ease and i refitted oem pads with copper slip on both rear sides in place of the pad that had fallen apart on the drivers side.

I checked the sliders under there rubber boots/covers and they had fresh copper slip on them to my suprise and were moving freely.
So next i unhooked the handbrake cables and they were freely moving in there outers as well and the lever arms that they hook into were free moving and screwing out the piston as i pushed them towards the front of the car.
All brake pipes and bleed nipples were intact with no leaks.
So no issues there neither.
So thats both pistons moving with ease on each caliper, handbrake cables moving freely and no sticky sliders.
So that rules out seized caliper and could only be "Dodgy friction linings on the pads" casusing them to part.

Whilst i was there i checked for play in my rear wheel bearings and there wasn't any (shouldn't be anyway as there only a year or so old as are the discs).

I forgot to say my brake fluid returned to the max level after i fitted the oem pads as the pistons were pushed in to fit them.


So a strange scenario i must say.............
The piston must have came out and unseated the seal as it twisted and caused a leak as i braked hard after loosing the lining.

 

[Rob669]

Re: FAO CS Mechy's - Is it possible for the rear caliper piston to come all the way o

Any idea what pads they were (just so I avoid them like the plague!). I thought that copper grease shouldn't be used on the sliders because it is slightly abrasive?