Removing corrosion behind brake piston seals

[Noxious89123]

I've heard people talk about corrosion building up behind seals causing brakes to stick, because of the extra pressure on the seals/pistons.

What is suitable to remove any corrosion in the grooves the seals sit in? My rear brake is a little sticky, and fancy having a go at stripping the calliper and giving it a good clean up and stick in some new seals, as it's only £11 all in for a set from David Silvers.

Pumping the piston out, cleaning it and greasing it with silicon grease sorts the problem, temporarily, but it soon returns. As far as I'm aware, the bike hasn't ever had them changed in 10 years, and it has seen road salt and the like.
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'06 Honda CBR125RW-6 ~ '00 Honda CBR600F-Y ~ '07 Honda CBR600RR-7 ~ Bikeless
'53 Ford Ka 1.3 ~ '03 Vauxhall Astra SRi 1.8 ~ '52 Vauxhall Astra SRi 2.2 ~ '53 Vauxhall Astra GSi

[Itchy]

Corrosion? Surely you mean dirt and road crud?

That is what causes pistons to jam, you might want to try better dust seals, or a smear of red rubber grease to prevent crud getting into the seals. My Honda ones need doing 6 months to a year. But some Yamaha ones are notorious for jamming up super quick.

Bog roll a bic pen top are pretty much all you need to remove the crud from the pistons. You can lever out the seals with the pen top. Then just use bog roll to wipe them down. Same with the grooves they sit in.

With the piston itself, just rub it against your hand, if you feel it scratch use soft plastic say a ruler to scrape off the rubbish. If it can't be scratched off then it might be time for a new piston. Some brake cleaner may also help but it is not needed.

Put some bog roll on the end of a match and swab the entire inside of the cylinder. Then rinse it with brake fluid, then reassemble carefully. Jobs done.
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[Robby]

No, he means corrosion in the caliper. The alloy corrodes behind the dust seals into white powder, forcing the seal to grip the caliper a bit more. Main cause of brakes feeling wooden. Older bikes need it doing every 5-10 years, I assume modern alloy is better.

Take out the seal, scrape out the corrosion with a dentists pick or a very small screwdriver. Don't scrape too hard, the stuff will flake off with very little pressure. Rinse with brake cleaner and reassemble with new seals.

[Itchy]

[Noxious89123]

Well I suppose the only way to find out if it's caused by corrosion or crud is to strip it down and take a look. Won't be doing it until the weather is a bit nicer, as I like to take my time and it's fcking cold ouside! No fun trying to do stuff with numb fingers.

Cheers guys.
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'06 Honda CBR125RW-6 ~ '00 Honda CBR600F-Y ~ '07 Honda CBR600RR-7 ~ Bikeless
'53 Ford Ka 1.3 ~ '03 Vauxhall Astra SRi 1.8 ~ '52 Vauxhall Astra SRi 2.2 ~ '53 Vauxhall Astra GSi

[evoboy]

[Robby]

My 1997 CBR600 was quite furred up, I assume it hadn't been looked at for 13 years. Both of my 1980 CB250RSAs were very corroded, but may not have been looked at for 30 years. My 1999 CB500 feels like it needs a look at the next pad change.

I know Yamaha RDs can be quite bad for it, but it may just affect some models more than others. A good smear of red rubber grease around the piston will doubtless slow the process down considerably, and they need to be very corroded before the brakes start sticking. Also seems to be more of an issue on bikes that have been standing for a long time with old brake fluid in, and stainless brake line fittings should accelerate the process.

Try stripping your caliper and see. They may feel fine now, but feel much better after having the corrosion scraped out. Far more feel with no corrosion, but you need a lot of corrosion before it feels as bad as a worn pad slider pin.

[DrDonnyBrago]

My CBR was spotless behind the brake seals, dirty as feck behind the dust seals though. Use a ball of tissue pressed into the groove and wipe it hard the whole way round. Use something plastic if required to scrape out any remaining crud.

[Kickstart]

Hi

Seems to happen to most bikes. Charlottes Triumph Thunderbird is really bad for it (but is a doddle to strip down). The ZZR600, FZ750 and FZR600 are quite bad for it. Both the 600 and 1200 Bandits have been fine. Most Italian stuff doesn't seem to suffer.

All the best

Keith
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[chris-red]

I think Sickpup told me to run a dremmel with a wire wheel round the inside to clean it up. Make sure it is a brass wheel that won;t damage the ally. I'd get somebody to confirm this won't knacker your caliper though as my memory is fuzzy and he might have never said this.
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[Kickstart]

[MarkJ]

I find a really small, like 1mm, allen key is good for getting the crud out. The angle of it helps as you don't have to angle a straight thing like a screwdriver in at funny angles to get all the crap out. Just don't press too hard.

[DrDonnyBrago]

[Kickstart]

Hi

Worth trying the nylon brushes (probably easier to get than the brass ones) but not sure they would shift the compressed ally oxide.

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[Suntan Sid]

When I did mine, I got the majority of the stubborn crud off with a bent piece of 2.5mm copper wire, carefully scraped around the groove.
For the final clean I soaked a plastic kitchen scourer in brake fluid and scoured away to my hearts content, came up nice!

https://christianhomekeeper.org/files/2010/04/scotch-brite.jpg

[stirlinggaz]

had this happen on a few bikes. (older ones, different makes)
now i just leave the caliper soaking in some solvent (paint thinners) or scrape out with a set of pick things (poundland, set of 4 or 5, hooked,angled,pointed etc - handy as f*ck),a good spray of brake cleaner & finish off with dremel & brass wire wheel.
the plastic/nylon bristled one started to melt,lol
cheers,
GAZ

[Noxious89123]

Bear in mind this is only the rear brake, the fronts are spot on

It doesn't exactly stick on, but it's as if the seals stick to the piston and pull it back into the calliper body slightly when brake pressure is released. It means that the rear brake lever permanently feels "long" because every time the brake is applied the piston moves out slightly before it applies pressure on the pads.

As I said above, cleaning and greasing solves the problem temporarily, and it feels massively better for it.

Thanks for all the advice guys; it's all very much appreciated. Will post up with the results when I finally get around to sorting it, which won't be for a long while yet!



EDIT: Just another thought:
Does bottled brake fluid have a shelf life. I've got a bottle which is unopened. Probably about a year old. This is ok, right?

When reattaching the brake line to the calliper, should I use new sealing washers and/or banjo bolt? I'd imagine the banjo is reusable but that the washers are a case of "you don't have to but..."
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'06 Honda CBR125RW-6 ~ '00 Honda CBR600F-Y ~ '07 Honda CBR600RR-7 ~ Bikeless
'53 Ford Ka 1.3 ~ '03 Vauxhall Astra SRi 1.8 ~ '52 Vauxhall Astra SRi 2.2 ~ '53 Vauxhall Astra GSi

[Mrs Vale46]

The way in which I clean all the brake calipers on all the bikes at my house is by taking them of and letting thm soak in hot soapy water ( use fairy liquid its the best I think lol) then using an old toothbrush and scrub away to ur hearts content.

I have given this advise to another brake/caliper problem sufferer hopefully its helpful as its the method I use on my nsr, my mum's fazer, my dads blackbird and the race bike. And its proven effective.

Emma-Louise

[Kickstart]

[Noxious89123]

[Kickstart]

Hi

In bulk from a fastener supplier is probably cheaper.

Something like these is also possible (not 100% sure on the size of them though).

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[Robby]

I get my washers in bulk on ebay, usually 2 or 3 quid for a 20 pack. Individual ones are really expensive. Not as bad as buying individual sump plug washers though, particularly when you can buy a big pack of superior dowty washers for a couple of quid.

[Noxious89123]

Good to know, cheers guys
____________________
'06 Honda CBR125RW-6 ~ '00 Honda CBR600F-Y ~ '07 Honda CBR600RR-7 ~ Bikeless
'53 Ford Ka 1.3 ~ '03 Vauxhall Astra SRi 1.8 ~ '52 Vauxhall Astra SRi 2.2 ~ '53 Vauxhall Astra GSi