changeing brake pistons how hard?

[bodgeitjo]

right time for the mot again changed spring and shocks( i went with the terrafirma all terrain +2) while they were off noticed the front brake calliper was soaked after examination the pistons were well pitted and rusty so orderd a kit off line is it just  a case of pull out piston clean and replace with new pistons and seals.   cheers  jo

[Range Rover Blues]

Hateful job.  There are 2 seals, the inner hydraulic seal isn't that bad, prise out and flip in the new one, assuming the housing isn't rusted.  The outer is a pain.  It sits behind a retaining ring that you are meant to prise out.  that housing will be rusty so there isn't enough room for the new wiper seal, then you should fit the new piston and finally slide the new wiper and reatining ring over the piston.

Rhubarb.  It never works for me.  I tried al sort of things including leaving the retainer in place.  I figured if  the calliper body has any corrosion it does not work.

Buy new ones, once a decade and look after tem, or fit SS pistond when still new.

[bodgeitjo]

thanx for the reply even if its not quite what i wanted to here oh well it"ll get sorted in the end.

[Hoover]

Probably best to just replace the whole caliper unit, this is what I did when i saw the state of mine!

Sometimes fixing things is just a waste of effort.

[Eightpot]

Mostly it's a straight forward job - get pistons out, remove the seals and then give the callipers a really good clean inside and out till they're spotless.
Fit the inner seals (easy), wet the inside with clean fluid, push the new pistons in leaving quarter inch protruding.
The next bit is the pig - fitting the wiper seals and retainer rings. Do NOT buy Britpart seal kits as the retainer rings just don't fit. They are an utter waste of time. Bearmach are just about passable, genuine ones fit much easier.   
Make sure the groove the retainer rings sit in is totally clean and free from crud - scrape it out with something sharp and pointy.
Buy more seal kits than you need as you will damage at least a couple of the retainer rings.
Getting them in dead square is quite difficult - it's not recommended, but in the end with one particular caliper, I found the only way to get the retainers in was to split the caliper in half giving easier access. 

Once you've finally completed this operation eight times, you may well wish you'd just spent the bit extra on some new calipers .