Brakes: Brake calipers refurbishing

[vlv240]

OK Mike. I will keep you informed.

Many thanks c_lee

[Clifford Pope]

I've never yet come across a sticking piston that I couldn't free off by working it backwards and forwards. I wouldn't use WD40 though, I use a few drops of brake fluid. It is excellent for penetrating and lubricating, and of course guaranteed not to damage the seal.

[dan 244]

I bought two new rear brake calipers from my volvo dealer in 2009, but they had to come from sweden so took about a week to come.

[vlv240]

Many thanks for the advice Clifford Pope and for the info dan 244

[czech240]

Originally Posted by Clifford Pope

I've never yet come across a sticking piston that I couldn't free off by working it backwards and forwards. I wouldn't use WD40 though, I use a few drops of brake fluid. It is excellent for penetrating and lubricating, and of course guaranteed not to damage the seal.

Agreed.....Give everything a good blast off with brake cleaner...then fill a small syringe with brake fluild to apply around the piston...work back and forwards and repeat....

[Clifford Pope]

If the piston is so stuck that you can't lever it with moderate force against the disc, take the pads out, remove the caliper on its hose, remove the disc, then refit the caliper. Now you can carefully drive a suitably packed wedge in between opposing pistons.
After you get a bit of movement, push the piston out again with pedal power, then lever back in again. Keep repeating until you regain full travel. Put suitable old pads or packing pieces in so that you don't blow the pistons out too far.

[Paul240480]

Yes, I've followed the advice of moving the pistons in & out to get them moving again. Once on the 240 & also on the 850 which failed it's last Contrôle Technique due to one being 'seized'. After a clean up it passed

As for bleeding, I'm a fan of the Gunsons Ezibleed kits, if you can get your hands on one, or a similar item I'd go for it

[vlv240]

Many thanks everybody for your advice.
I'll try to get a Gunson's Eezibleed.
And will keep you informed about the progress.

[chesters6]

trouble is if you dont remove the pistons the reason they stuck is still there.
it tends to be a rusty band that forms ,moving the piston could abrade the inner seal .
IMHO its best to remove the piston clean it up and use a new seal.
I tried the mechanical force bit but my pistons were stuck in so there was little to push against and i actually broke a G clamp trying to move it a fraction more to unstick it.
one was halfway out which moved with a thin chisel between the pad and disk.

i eventually refurbed them all and even the free ones had signs of the rusty ring forming and a surprising amount of watery rust in the calipers ,i guess it had been neglected since it was made
i guess if their stuck in its water in the brake fluid if stuck out its water penetration via the dust covers?

[vlv240]

@chesters6: You are right.
That's why I intend to remove all pistons, clean everything and replace all rubber gaskets, and renew as much as possible from the braking system components - that are used and need replacing, naturally.
Most of the braking system components are old, used so this, as far as I think is the best solution.
As I already spent a lot of money on spares (for my possibilities) I will do this on my own (plus I don't have a refurb shop/specialist here)

Any other opinions/advice are welcome!