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Discussion Starter · #1 ·
How does everyone clean the pistons on the front callipers when replacing the brake pads? I am familiar with the process: push the pistons out a little so toy have access and then used a toothbrush and brake cleaner.

But the callipers are mono bloc and there's no access through the top so how do you clean the top (hidden) part of the pistons so that you don't push dirt past the dust seal — and back into the caliber — when you're installing the new, thicker pad?

Much thanks
 

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Methylated spirits and a toothbrush. If there are small tar covered bits of grit I will run the blade of a small flathead screwdriver CAREFULLY around sideways to get those out. Road maintenance thing here, what's used to patch holes is very fine tar covered gravel and DL calipers are magnets for that shit.

You can also push the pads out a little using the brake lever to make the surface more accessible. I usually put a small piece of wood in there or one of the old pads just to make sure the pistons don't push out too far. If they look crusty- scotchbrite and meths again. Used gently it won't harm the piston surface.

Pushing them back, first comment, don't bleed the brakes/change fluid until AFTER you changed the pads :).

Slip the old pads back in (No need for the pins) or find something thin and tough you can put each side (3-ply plywood for example) and lever them back by putting something between the old pads and prying - far enough that the new pads will fit. I have a large screwdriver I use for that. Provided there isn't too much fluid in the system you have around 20 seconds to put the new pads in.

If you pushed the pistons out some for cleaning, just leaning on whatever you used to stop them popping out will get them back far enough to get another old brake pad in there. The tough bit is those last 5mm or so.
 

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With the calipers removed from the forks and the pads / shims / springs removed there is access to the pistons from both the top and bottom of the caliper.

Brake cleaner is fine for this application as long as you used compressed air to remove / dry. You don't want to have the seals soaking in brake cleaner for any length of time because they can swell, but surface cleaning of the pistons then blowing them dry is fine. I normally use a toothbrush to help the brake cleaner do it's thing - but Q-tips are handy as well.
 

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Discussion Starter · #9 ·
Hillsy, one thing i noted the last time i did this is that by the time the pads are worn enough to be replaced the pistons are already protruding enough that it's impossible to get out the springs past them. I had to push the pistons — with dirt on the top of them — back in to get the springs out. Sort of a catch 22. Your solution?

and thanks
 

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My technique is to cut a thin strip of those (fabric like) abrasive kitchen pot scouring pads (in Aust they are usually green in colour) wrap the strip around the extended pistons and clean with a see sawing action.
Works for me and the material does not mark the piston.
 

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Hillsy, one thing i noted the last time i did this is that by the time the pads are worn enough to be replaced the pistons are already protruding enough that it's impossible to get out the springs past them. I had to push the pistons — with dirt on the top of them — back in to get the springs out. Sort of a catch 22. Your solution?

and thanks
I guess for me if it got to that point I would pop out the pistons and clean them out of the caliper. It would take quite a while for the pads to wear down to that point and if you don't clean the pistons regularly the exposed areas would probably have a fair bit of crud on them.

That's probably just me though - I often meddle with older bikes or bikes that have been sitting so I am no stranger to pulling calipers apart. Just another maintenance job for me.
 

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Discussion Starter · #12 ·
Hillsy, I used to go through from brake pads every 50,000 km in Canada. But now that I am roaring up and down the Stelvio pass, front brake pads are lasting about 8,500 km. Can't pop them out every time :)

Thanks for all everyone however, your suggestions have given me some food for thought and a plan is formulating. My many thanks.
 

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I use strands of a unicorn tail dipped in angel tears to clean calibers. When I cannot source the aforementioned I use brake cleaner and a soft brush but mostly brake cleaner. Its not rocket surgery its cleaning brake dust off a caliper piston.
 

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I recently read that the NO CHLORINE brake cleaner is caliper seal safe.

However, my go-to for heavy cleaning the past number of years is Simple Green industrial strength diluted per the label, NOT full strength. I use it in my ultrasonic cleaner for carb bodies and parts, too. Available in Italy?
 

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Discussion Starter · #15 ·
please re
I use strands of a unicorn tail dipped in angel tears to clean calibers. When I cannot source the aforementioned I use brake cleaner and a soft brush but mostly brake cleaner. Its not rocket surgery its cleaning brake dust off a caliper piston.
please read the original post again.
 

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I use a dry, soft, paint brush (the real hair kind) and brush lightly in and around the piston areas while simultaneously blowing the area with an old hair blow dryer. No solvents and no compressed air.

Then strips of t-shirt moistened in brake fluid. Work around pistons where ever they are at extended, don’t move them till cleaned.
 

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Discussion Starter · #17 ·
ST and Perazzi, just saying that the problem is not general cleaning but rather gaining access to the top half of the positions that are not accessible by toothbrush, paint brush or a soft brush. That's why the shoelace soaked in brake fluid and then placed over the inaccessible part of the piston sounds like a solution.
 

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I use a brake piston removal tool to turn the pistons for easy access with brake cleaner on a toothbrush. See my post on this thread......

 

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I use a brake piston removal tool to turn the pistons for easy access with brake cleaner on a toothbrush. See my post on this thread......

Hey, thanks; I never knew about those. That looks a lot smarter than my method of using compressed air, which invariably sprays brake fluid everywhere ...
 
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