Stainless steel caliper pistons?

[ST1100Y]

Would apply to all mounts, but no distinguished [brakes] section in [general tech]...

Those sets appearing from various aftermarket vendors all over the place...
I'm hesitant over the known corrosion issues of a material mix (stainless vs aluminium, or the steel of the carrier plates)
Anyone gave them a try yet and can provide some long term results/observations?

 

[Oldbikefixr]

I put stainless pistons in the 1978 GL1000 I restored in 1991, all three calipers. We rode it for 78000 additional miles with no issues. I would't hesitate to use them next time.....from a reputable supplier, anyway.

 

[RaYzerman]

The caliper pistons don't actually touch anything, separated from contact by the seals. Most of the caliper pistons I've dealt with look like brass, which reacts with aluminum also.

 

[Oldbikefixr]

The caliper pistons don't actually touch anything, separated from contact by the seals. Most of the caliper pistons I've dealt with look like brass, which reacts with aluminum also.

They are not seeing any/much metal to metal contact so galvanic corrosion isn't a problem. Old/torn seals will allow moisture and whatever else can enter the cracks to cause corrosion on the piston that resides outside the seal. Also.....failure to bleed your brake system regularly will permit absorbed moisture to percolate down into the caliper cavity and.....corrode the 'upper' surface of the piston as well as the inside of the cavity.

 

[ST1100Y]

The caliper pistons don't actually touch anything, separated from contact by the seals.

Figured that, but
- how "conductive" is brake fluid?
- what about the road "brine" (spray) on the exposed side when riding in the rain?

Most of the caliper pistons I've dealt with look like brass, which reacts with aluminum also.

The last Honda ones I'd installed were steel with yellowish coating (zinc galvanized).

 

[ST1100Y]

Old/torn seals will allow moisture and whatever else can enter the cracks to cause corrosion on the piston that resides outside the seal.

I overhaul them as soon as I cannot push them fully back in by hand...

Also.....failure to bleed your brake system regularly will permit absorbed moisture to percolate down into the caliper cavity and.....corrode the 'upper' surface of the piston as well as the inside of the cavity.

Fully agree and state that most premature ABS modulator failures root in sloppy/irregular fluid replacements...
I use like two bottles on my non-ABS for front, clutch and rear brake system, so I figure 3~4 for an ABS/CBS to ensure real good flushing.
Replacing only the equivalent of the reservoir volume is by far not enough to clean all out as good as possible.