Topic: Are my caliper pistons shot?

[Motoguy23]

I'm doing a dual disk conversion and both of the calipers I have were stuck so I dislodged them and this is what I found.

Can I wire wheel these or do I have to bite the bullet and get new ones?

[TwoTired]

You CAN use them.  They will safely stop the bike, won't leak.  I've re-used them in far worse condition.
The only issue those may have is proper retraction.  If the square section seal gets into the corrosion pits, it  may not do a proper .004 retraction.  Then you may have some unwanted brake drag, which may or may not be significant.

If you are not afraid of doing the work twice, you could just try them, and if they drag, get new ones, or the phenolic types from Kevin400F.

Cheers,

[florence]

I would say replace them.  They will chew up the seals and let air in.  Why take chances with brakes, new pistons aren't too expensive.

[Brown Bomber]

     Equally important is the groove in the caliper where the seal resides. Like TT said, it is a square section seal and the groove in the caliper has a small ridge in the middle of it for the seal to rock back and forth on. It's not much of a ridge to begin with, and being aluminum, it tends to oxidize under the seal and eat up the ridge, so be careful not to scrub too hard when cleaning that out. If that little ridge is shot, the seal won't retract the piston. (I had to learn this the hard way )

[bryanj]

Only question i got is how much is your life worth

[Kong]

Well, failed seals don't let air in, they let fluid out.

Go ahead and use them but keep a new set in mind and search.  Before you put them back so to your local hardware store and pick up a sheet of emery cloth, the fine stuff if they have it.  Rip off a ribbon of it about an inch wide and in a see-saw motion, with the ribbon of cloth wrapped half way around the piston, you can clean that down to a smoother surface.

I've seen some composite pistons for sale as replacements that are much less expensive than their plated steel counterparts.  They are what I will be putting in both of my calipers when the bike goes back on the road.  I believe the things can be had for less than $30 each off of E-bay, but that's just off the top of my head, I haven't bookmarked any sellers.  I've got one of the seals setting on the dash of my truck as a reminder to stop at a hydraulics shop and see if I can find an inexpensive standard ring for replacement purposes - I'm pretty sure I can, and that too will save a good bit. 

[Duke McDukiedook]

That sidewall looks severely pitted/rusted and will just cause you woes.

PM Kevin400F about phenolic pistons and worry no more about corrosion.

[nokrome]

at least clean them up and see what they look like first before you drop money on new ones,
  i wouldent use a wire wheel though, red scothbrite will remove that corrosion whithout affecting the o.d. of the piston

[Toxic]

a new rubber seal can be had from Honda for $5.00

[Kong]

That sidewall looks severely pitted/rusted and will just cause you woes.

PM Kevin400F about phenolic pistons and worry no more about corrosion.

These are the replacement I was thinking about, I didn't realize they were being made (machined) by one of the folks from here.  I had the cost off by a little bit, they are about half the price of one new one each.  These are what I will put in my in-progress dual-disk front system.  To my mind this upgrade is almost mandatory, offering both outstanding dimensional stability but also being immune to corrosion.

[TwoTired]

at least clean them up and see what they look like first before you drop money on new ones,
  i wouldent use a wire wheel though, red scothbrite will remove that corrosion whithout affecting the o.d. of the piston

That's a good point.  The stock piston is plated to achieve proper diameter.  I suppose if you used a brass wire wheel or a really soft one gingerly, it would be ok, though.

Cheers,