Dale has said one way of removing the pistons, and it will work.
But w hy waste the brake fluid? DOT3 is made to absorb moisture and it has dried out changing it to a crystallized DOT3 fluid. I use a bucket of clear water and do much the same as he suggested.
Only; after opening all the screws, bolts and fittings to allow the water to get in (for an hour or two). To remove the pistons, I leaving the end clip and washer off the open end and use bolts to cap off every opening but one of the end ones and then just blow it out with compressed air back into the bucket of water. Or, I have used a canvas bag to catch the pistons as they will come out rather abruptly. Digging, picking and banging at things can make a mess and even damage the cylinder or pistons. And, if the pistons come out right I have had some success of using the seals again. (It depended a lot on "IF" the crystals had cut into the rubber).
And don't forget; there is a small bleed-back hole in both of the reservoir inlets (one is larger than the other) that will need to be opened with a sharp object or very small drill.
Always take pictures, notes, draw diagrams of how things go back together. Even the check-valves (I use a small magnet to get them out) are different for the front or rear brake systems. The pistons will have to come apart, measure them to make sure they are the proper length when you put everything back together. When assembling the master cylinder use a lubricant, DOT3 will work, but I like Barryman Assembly Lube.
Contact them at info@...
to ask about it.
Bill
> -----Original Message-----
> From:
> 2cylinderhondas@yahoogroups.com [mailto:2cylinderhondas@yahoogroups.com] > On > Behalf Of > goinhm@...
> Sent:
> Sunday, February 21, 2010 7:28
> PM
> To:
> 2cylinderhondas@yahoogroups.com
> Subject:
> Re:
> [2cylinderhondas] master cylinder rebuild effort
> Here are my suggestions (I'm sure you will see
> others)..... .
> 1) remove as many of the fittings on it as possible (the section > where the brake reservoirs are connected and the stop light switches and > anything else you can remove
> 2) soak in brake fluid (I have seen others mention warm water > but I use brake fluid)
> 3) remove the bolt at the very front (and side) of the
> MC (it has a 10 mm head) and remove the circlip at the rear of the MC > which holds the pistons in place. Try using a small pin driver or > screwdriver through the hole in the front (where you removed the 10mm bolt) to > push the piston assembly free.
> 4) If this doesn't work (and it may not since the piston
> assembly is spring loaded), let it soak for several days and then try > slamming the rear section against a piece of wood. You can also try > tapping on the MC with a plastic mallet to set up some vibrations which may > free things up (don't hit it with a metal hammer.... you don't want to damage > the MC). If you had access to an ultrasonic cleaner, this could be > helpful.
> If it doesn't come free, let it soak some more and every day try > slamming it against the wooden block. You can also heat the MC with a > heat gun or hair dryer (If you use a propane torch, you need > to be very careful).
> If you still cannot get it free, you may need to accept that even > if you do get the assembly to come out, the entire cylinder is going to > need rebuilding (re-sleeve the cylinder, replace all the seals, > replacing any of the other components which are damaged). This is where > it can get expensive. Miles may still be selling the > seals.
> When it gets to this point where nothing is working, you can heat > up the MC until the seals and the dried brake fluid (it turns into a compound > which reminds me of dried rubber cement) are hot enough that everything > slides out. And then you can rebuild the whole thing or pick up a used > one from someone on this post.
> I have found that it just takes patience and persistence to get the > assembly to come apart. At a minimum, you are going to need to > clean the bore and replace the two piston seals. It is very likely the > bore may need to be re-sleeved.
> Good luck,
> Dale
> > I have the MC out
> > and I am having a couple of problems taking it apart. As I said, the fluid > > had gummed up over the course of 10 years sitting. The piston is completely > > depressed within the cylinder and will not budge. I don't want to use too > > much force and mess anything up. How should I go about getting this thing > > apart? Should I soak the whole thing in brake fluid for a couple of days?
> > Can I use something to stick down in the cylinder and pop out the > > piston?
> > Most of the buts/bleeders are stuck on there and I don't want to > > round off the nut. The penetrating oil hasn't done the job quite yet, but I > > remain hopeful. Suggestions on breaking this thing down?
> > Thanks.