Dismantling rear brake calipers

[radek at istar.ca]

Hello Group.

I've had no luck getting responses to my question about  brake fluid resistant O-rings.  I
keep looking
for a supplier.  If I find one, I'll post the coordinates.

Another question to those who had dismantled their rear brake calipers:  is there an
internal spring under
the piston?  In the caliper I'm working on, there is just a threaded rod but no spring.
Is this OK or did
the rebuilder forget to put one in?
TIA

Radek
88
90Q