Hi Jeff,
I made a tool to help remove caliper pistons on my TR4, might help you
too. It's nothing more than one of those rubber replacement engine
"freeze plugs" that are available at most auto parts store. I welded a
flat steel handle on the large washer that makes up one side of the
"sandwich". When you tighten the nut on the freeze plug, the rubber is
squeezed between two washers & expands. Before tightening, it fits
loosely into the back of the caliper piston. When I tighten it, the
rubber expands and gets a good grip inside the piston. I can usually
then rotate it enough to break it loose and work it free from the
caliper body.
9 times out of ten, it's old dried up brake fluid that "glues" the seal
and piston into the caliper body. Sometimes just drizzling a little
fresh brake fluid around the edge of the piston helps, too.
I've also heard of using a bicycle pump to put some air pressure in the
caliper to pop the pistons loose. Another lister while ago said he used
a grease gun, pumped the caliper full until it pushed the piston free.
Ideally, you could use the hydraulic system itself to pop a piston
loose, by clamping all the others and pumping on the brakes a bit. Of
course, it's usually the last piston that won't come out!
Alan Myers
San Jose, Calif.
'62 TR4 CT17602L
Jeff McNeal 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
--
MZ
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