The rear brakes on the Superb started squeaking and grinding, decided after nearly 70K it's time to change the discs and pads.

 

I can't wind in the caliper piston, I have (an aftermarket version) of the correct tool (T10165), the hand brake is off but it just won't move.

 

Do I need to replace the caliper?

 

Cheers

Have you used the tool on another vehicle before, do you know how to use it?

 

If so then please describe the difficulty that you are encountering, describe what you mean by the piston won't move.

 

I am not being obtuse, there is a reason for asking.

Edited 25 March, 20233 yr by J.R.

Not done mine yet but does the auto hold handbrake affect wind back of the pistons. Just a thought if a different method is required?

Have you taken the reservoir top off.

I don’t have hill hold as someone mentioned in another comment.

Mines just a straight forward Caliper with handbrake.

I got a Lazer tool from Halfords, it is tight to wind back so just need to be patient and take your time 

The tool was last used on an L reg Passat Estate, it's a sykes pickavant tool but I've checked and it does fit. I've used the tool before and double checked the genuine repair guide to make sure I'm turning it the right way. 

 

It does have hill hold control but the cars been turned off for a good couple of days and the wheels turned before I started. 

 

The tool isn't moving at all, I'm wondering if the caliper has siezed? The car is 13 years old and done 130K miles. 

It may have seized, sorry for my earlier question but at least we have established that you know you have to rotate the piston (as well as applying axial pressure).

 

The pistons move back and forth and never rotate aside from when being withdrawn with the tool, as such they can be very sticky initially and I frequently resort to a pipe over the short Tommy bar to get the initial movement.

 

Some have left hand rotation but even if you were trying the wrong way through say an incorrect manual it would still move but bind the tool.

 

With the caliper ask an assistant to gently push on the brake pedal to check for seizure.

 

I have no experience with hill hold systems (and hope to avoid them), it would be interesting to know if it needs a different procedure because of it.

 

I would think if the handbrake operates OK then at least one of the pistons must be moving freely.

Edited 26 March, 20233 yr by J.R.

Have you cracked open the bleed nipple and attached a tube to catch the emitted brake fluid once you start retracting the piston ?

He hasn't been able to start retracting the piston.

 

I have been winding them back for 30 years now without ever needing to open a bleed nipple, I would only do so if the old pads were worn out and the master cylinder reservoir had been topped up to the brim.

 

In fact i would not then unless I had misplaced my suction syringe.

Does this car have electronic handbrake?

Hill hold will make no difference to the wind back procedure. Hill hold uses the ABS pump to apply the rear brakes using the hydraulic circuit, so not really different to applying the pedal from the caliper's perspective. When the car is off the brake can be wound back normally. If your windback tool has a square drive on it, you could use a ratchet or breaker bar to get it moving initially. I'd also check that the handbrake is off.

Squirt some of our favourite release spray in behind the outer seal and leave it to soak overnight. Grab the piston with a pair of grips and give it a rotational wiggle back and forwards before you put the windback on. 

I had a similar problem with one of my rear calipers recently. It was seized and the brake pipe had corroded. Previous owner was a bit tardy with the brake fluid changes and the fluid was contaminated with moisture, which probably contributed to the problem. If you cannot wind back the caliper it is probably seized. Do check the bleed nipples as three of mine were seized when I tried to bleed the brakes!

It's been to my local mechanics, both rear calipers are siezed.......