Caliper cleaning/old brake fluid

[Sarcvicious]

I’ve torn my calipers down, and the pistons are in great shape, but the actual part of the caliper that holds the piston has brown stains from the old brake fluid that was sitting for god knows how many years.

ive cleaned the calipers with brake kleen (enough to where the paint is mostly off), but I can’t get the brown film off. Any suggestions on what to use to get this off or what else I can try?

if I don’t get the brown off should my calipers still be ok since the pistons are in good shape?

[Nessism]

Carb dip?

Important thing is to remove any corrosion or crud in the seal groove and off the pistons. Then install new seals and your calipers should be okay. Use heavy black moly caliper grease for the sliding pins. Replace the lines too.

[Big T]

Wire brush or blasting
Repaint
Be sure all residue is off before Assembly

[KiwiAlfa156]

With new seals make sure the piston and the seal are well lubed up with brake fluid. Too much friction between the seal and piston will stop the piston slipping through the seal to self adjust for pad wear. It will cause excessive lever travel, you'll think it's air in the line, but bleeding will not fix it

[bwringer]

Wire brush or blasting

Yes, but NOT inside the bores!

Just to be clear...

[Sarcvicious]

Thanks for that clarification. The brown spots are inside the bore.... i tried to use sandpaper by hand a bit and it worked... did i totally just mess up my calipers? Having a blond moment here.

[Gorminrider]

The piston surface that contacts the rubber seal is the only one to care about....Immoveable (iron-oxide?)stains in the bottom of the bore are unlikely to hurt anything. It's probably molecular from the old hose fittings....

[Rich82GS750TZ]

I'd have reached for a green scotch brite pad. That and WD40 (right or wrong) have been my go-to for cleaning gunge off/out of aluminum parts: gasket surfaces, brake pot recesses, and lots of other stuff. You have to press super hard to removes anything but the offending crud. If I need to get more aggressive or feeling lazy I go for these on my dremel. Worked a treat on cleaning up the inside of my front wheel that had a lot of corrosion. They wear quickly and a bit pricey, but sometimes I just don't feel like spending hours rubbing with a pad by hand.

[Gorminrider]

yes ^^ handy, but not "harmless"- scotchbrite can do a lot of harm in the wrong place...Whenever polishing. I remind myself water can wear a stone

[Rich82GS750TZ]

yes ^^ handy, but not "harmless"- scotchbrite can do a lot of harm in the wrong place...Whenever polishing. I remind myself water can wear a stone

Yes, I understand that the scotchbrite is abrasive and if you're not careful, can remove aluminum, But with all the gasket surfaces I've cleaned with it, I found if I keep it wet w/ WD40 and let the pad do the work, w/ only a little pressure, I think I do OK. YMMV.

[Rijko]

^^ +1 : using the soft scotchbrite and WD40 i have
never seen scratches created in the bores.

Those are handy too : after most crud is gone i
wrap them thick in cloth and put some Belgom Alu on it.
The bores on my calipers shine like chrome

Did i mention i like shiny things ?
I also polish the brass parts in/on my carbs like plugs,
jets, choke, fuel pipe, etc.

[Rijko]

^^ +1 : using the soft scotchbrite and WD40 i have
never seen scratches created in the bores.

oh wait i have ... the central part of the Dremel tool could damage
the bottom of the caliper bore, so i always use it at an angle so
that won't happen.

Though scratches on the bottom don't hinder functionality
i dislike them as the purpose is a mirrorlike finish, and
improve not damage the calipers.

[Nessism]

The condition of the bore isn't important, just the seal groove. Use a gray scotchbrite pad or brass wire wheel on a dremel, running at low speed, and remove all corrosion in the seal groove. Then install new OEM seals, and make sure the pistons are not pitted. Do this and you will be good.