rear caliper operation question

[stenky]

i have rebuilt some mk2 rear calipers recently, but the working principle is the same as on mk1.

ok, on one of the calipers, when pulling the handbrake lever, the piston goes outwards, but as I release the lever, piston slides back in. on the other one, after releasing the lever piston stays and doesn't go back. which one is behaving correctly? is this an issue?

[Polypedates]

The first one is operating correctly I would think. On the Mk1 caliper there is a large external spring that serves to retract the piston again when the handbrake is released:

[monkeymax]

It sounds like the piston is sticking a bit on the second one (the first one - from memory, as it's been a while - is operating like it should.
The internals of the caliper are pictured here:
http://www.imoc.co.uk/forums/kb.php?mode=article&k=118
One of my rotten calipers had rust on the outside of the piston which was causing it to stick, so I got a new piston when I refurbed it.

[stenky]

Looks like i haveth to disassemble the second one and check the seal.