Topic: FRONT BRAKE PISTON REMOVAL - HELP

[sniper1]

I am replacing the rubber seal in the caliper. I have the caliper apart but can not get the piston out. Any thoughts on how to remove it???

[Mainerider]

Yes
Take an air hose and place it in the banjo bolt hole, pout a rag over the pistyon and cup it with your hand. Shoot the air in and it will pop right out. A min 30 lbs pressure or so should do it.

[Mainerider]

PS
If you don't have an air compressor go to a local garage and I'm sure they will let you use their hose. Sorry for typos. On my BlackBerry.

[sniper1]

I'll give it a shot and let you know how it goes.

Thanks for the fast response.

[Kong]

Search for "grease gun"

[Mainerider]

Oh it will pop right out. That is the factory method for removal-grasping the piston and pulling on it will only mar the piston.

[sniper1]

Air compressor worked like a charm! Thanks alot!

Now, How do I get the seal out without marring the cylinder up?

[Kong]

Stab it with an awl, and drag that silly $%^&ard out kicking and screaming.  Really, just get something sharp and pick it out, you're going to replace it anyway.  Make sure you clean the groove real well when you go to put it back together.

[Mainerider]

First off Honda says to replace the oil seal whenever the piston is removed. Personally, I think this is overkill if the seal looks to be in good shape. If you do need to replace it your best bet is to use a hook and pick tool.How pitted is the Piston and cylinder? Gently work it out of its seat. As said though, if it looks ok I would try leaving it alone. I have an 80 650 and this front brake is nothng to brag about even in the best condition. Riding one of my sportbikes shows just how far susp and brakes have progressed.

[sniper1]

The piston and cylinder look good, no dings or divots. The problem was the brakes were squealing like hell, and brake drag. The pad would not "retract". The seal looks Ok, but I will replace just in case. Any idea on type of lube to use?

I know what you mean about how far suspension and brakes have come over the years. I have almost the whole lineage......a '67 BSA thunderbolt, '77 cb550, '95 cb1000, '04 VFR Interceptor. I would love to put the vfr brakes on the 550.

[Mainerider]

That's is so true. I also have an 04 Non ABS VFR along with a mint '96 Viffer. Re grease I use a silicone based grease. NAPAs Sil-Glyde is a good example.

[sniper1]

Finished it all up and works good, squeal is gone. Now It seems as though there is brake fluid leaking from the cap of the master cylinder. It's on thight and the internals are all there. Any thoughts on that?

BTW, thanks for all the help!

[dcil]

Glad you got it fixed. For future reference, if the inside of the brake hose is collapsing it will cause drag, since there is no pressure when fluid returns. As far as the m/c leak, could be over filled.

[Mainerider]

Glad to help. Could be a couple of things. First, are you positive that it is the cap? If so, then it is probably on too tight and is squishing the diaphram. If it is actually weeping around the base of the cup then it is your o ring reservoir cup seal. I have a brand new seal and cup on mine and it still weeped. Had to use Seal-All around the perimeter. These MBCs  are known to leak. 

[MCRider]

Glad you got it out with air.

One caution for those trying this, put your hand over the piston, maybe with a cloth, becuase the piston can come flying out at speed.

And since the topic will attract readers, I'll add what Kong alluded to. I had a piston that would not come out with air, 110psi. From a suggestion here, i did the grease gun method. Unthread/remove the tip from your grease gun hose. You'll have a male threaded end exposed. Thread it into the hose entry port of the caliper, with the other port closed off. Its not the same thread, so you'll only catch a few threads before it gives resistance and you should stop there to avoid damaging the caliper. Then pump the gun and to my surprise the piston came outsmoothly and easily, with about 5 pumps!

You'll have a caliper full of grease, but removal of the stuck piston is well worth it.

[Hondawggie]

Air compressor worked like a charm! Thanks alot!

Now, How do I get the seal out without marring the cylinder up?

If you find a store locally or online that sells tools, search on "brass o-ring pick" and you'll be able to buy a pick made of brass that will make it less likely you'll damage/scratch the o-ring groove.

This brass o-ring pick I use is *specifically* designed for o-ring removal.  I got it when I worked as a technician on high-vacuum metal deposition machines that deposit metal on semiconductor IC chips during their manufacture.  The high-vacuum machines I worked on had lots of seals, thus lots of o-rings so we were removing/cleaning/reinstalling o-rings constantly.   

We used IPA (isopropyl alcohol, aka 'rubbing alcohol') to clean the orings.  The brass o-ring pick didn't damage the o-ring grooves in the metal (brass is a softer metal than most others).

[somesuch]

I like McKay hydraulic cylinder assembly lube. (http://www.airosol.com/50600.html)  It is a (silicone?) lube, and works very good. It is a bit thicker in viscosity then Raybestos stuff that I used. i do NOT like the Permatex brand. It comes out like silicone grease, but seems to break down with time and form a crappy looking goo.

McKay seems to retard corrosion in a big way, makes assembly very easy, and is a "must" if you are not filling the brake system with brake fluid right away.

[nokrome]

ive had a couple that were seized really bad, 110psi wouldnt budge it and the grease gun just made a mess so i ended up gripping it lightly in a vice and putting some moderate heat on it from a propane torch and then applying air pressure, pops right out with no fuss.
   just dont have it aiming at your face while your doing it 
      this topic should be in the faq