Here's another (messy) way to extract the piston from
the caliper:
Connect it back up to the hydraulic system (loose, not
mounted), wrap it in towels, and push/pump down on the
brake pedal.
This will create about 1000-1500 psi (the design
working pressure of the brake system), and pop the
piston out.
If the piston will not come out this way, you can
pretty much forget it.
Have you already removed all the other brake
components? No problem as long as the clutch master
cylinder is still mounted:
1) Unscrew the fitting where the metal clutch line
connects to the MC, bend it slightly out of the way.
2) Screw the caliper flex hose end into the hole in
the MC where the clutch pipe was. They are both
5/16-24 threads. Of course, be careful not to bugger
the threads, be CLEAN, and do not overtighten.
3) Thread the other end of the flex hose into the
caliper.
proceed as above, wrap caliper, push/pump clutch
pedal, etc. You may have to add more brake fluid to
the resevoir.
Good Luck!
--- Jeff McNeal <jmcneal@ohms.com> wrote:
>
> Hi again. A special thanks to John C. Smith, a list
> member from Ohio, for
> the many helpful e-mails he's sent me advising me on
> how to extract my
> caliper pistons for a rebuild. If you want to see
> how horrible the seals
> looked, I've posted pictures on my project page:
> http://www.ohms.com/spitfire/projects.shtml down
> near the bottom of the
> page.
>
> My biggest surprise was the discovery that one of
> the pistons had no circlip
> or outside seal whatsoever. No WONDER this thing
> couldn't hold fluid in the
> reservoir! Duh! Is it possible that the clip and
> seal became dislodged and
> lost somehow? Or did someone get sloppy when they
> last rebuilt the caliper
> seals way back when? I couldn't BELIEVE that when I
> saw it. As I stood
> there staring at the missing seal, the importance of
> doing this stuff
> yourself really hit home for me.
>
> Unfortunately, one of the pistons is stuck and I
> can't seem to get it
> dislodged from the cylinder no matter what I try.
> I've attempted to wriggle
> it out using needle-nose vise grips (not on the
> surface that comes in
> contact with the cylinder!), I've tried tapping the
> outside of the caliper
> with a hammer to break it loose and I've given up
> for the day after an hour
> of trying. I've sprayed the edges of the piston
> liberally with WD-40 with
> the intent of trying again tomorrow, after the
> lubricant has hopefully
> penetrated further into the piston cylinder. Now
> that I've sprayed WD-40 on
> there, are there any special precautions I should
> take before refilling the
> system once I DO get that piston out and the new
> seals in place? In other
> words, will traces of WD-40 cause problems with
> either the new rubber seals
> or the silicone DOT 5 that I'm going to use?
> Thanks!!
>
> Jeff
>
>
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