Article [13] ST1300 - Rear Brake Piston Cleaning

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Joe
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Joe - I do everything you show but I have one more additional step. I place a piece of wood in the caliper bracket, then pump the pistons as far out as I dare to effectively clean the whole piston. The thickness of the wood is a trick. It's thin enough to allow the piston to extend out a ways, but not too far to allow them to pop out of their seating.
Not bad... so the rotor thickness plus the base of two brake pads should do.. I've seen a bike come in with no pads left and pistons were sticking so maybe add just a hair to that... 1/4 inch..
 
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Joe - I do everything you show but I have one more additional step. I place a piece of wood in the caliper bracket, then pump the pistons as far out as I dare to effectively clean the whole piston. The thickness of the wood is a trick. It's thin enough to allow the piston to extend out a ways, but not too far to allow them to pop out of their seating.
Ditto. And as for the response from CRC, I already got one!! That was quick.

Dear Bernie:

Solvents generally will effect rubber materials so minimizing the contact time is the best way to have the least amount of issue. Solvents that contain the same elements as the rubbers will have more effect than other solvents. E.g. a chlorinated rubber such as chloroprene will be effected by perchloroethylene (Perc) more than it would by methanol. EPDM would be more effected by petroleum solvents than chlorinated solvents. But since brake cleaners are usually fast evaporating they usually do not attack the rubber aggressively because they are not in contact with it unless the solvent is allowed to stay on them for a longer period. The worst case is the solvent will swell the rubber but when the solvent is gone the rubber, being elastic, will go back into shape. Since you do not use brake cleaners daily the effect would be much less.

In conclusion, if the cleaner is used infrequently and the contact time to the rubber is minimal you probably will never be able to tell the rubber has been effected. Please let us know if you have additional questions.

Sincerely,
Melodee Nemeth
Product Development Manager & Technical Support Supervisor
CRC Industries, Inc.
 
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I should have also added that I use Teflon to clean the pistons. A can of Tri-Flo that you can purchase from any bicycle shop.
 
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That was quick though not exactly a ringing endorsment of we designed it specifilcally to be used on pistons and seals LOL.
The brake fluid works for me.

BTW tri-flo contains hydrocarbons ok for o-rings and seals not ok for o-rings and seals that are compatible with brake fluid.

Whohoo! another oil thread. :)
 
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BTW tri-flo contains hydrocarbons ok for o-rings and seals not ok for o-rings and seals that are compatible with brake fluid.
In my 25 years of using it, maybe once a year on each bike, over 6 different bikes, one with 100k miles, never had brake seals fail from it, sorry for all the commas.

Seriously, I think we can get too wound about the interactions of solvents, rubber, plastic, etc. The only time I had something seriously damaged from a solvent in all my life was the inner bits of a chainsaw, including the fuel pickup hose, totally disintegrated when my Father in Law left ethanol gas in the tank for 8 years.

My favorite is when people warn me about using WD40 on my motorcycle O-ring chains. "The lubrication is not good enough for that use" and "the solvents will eat the O-rings" are the two lines I am always dished. Yet I seem to manage to always get at least 25k miles out of my chains. Go figure.....
 
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I pretty much agree with you. It's like an oil thread in that regard but it's good to know at least the reasoning behind the oems recommendations before taking a short cut. My thought is I already have brake fluid that's been open don't want to use it in the hydraulic system but it makes a dang good cleaner. TMI o-ring linky



BTW although off topic Parker, pretty big name in o-rings says your best bet is to call them regarding ethanol in fuel. Below doesn't leave you with a warm fuzzy feeling with the gobment pushing for 15% ethanol.

"For the latest information and test data regarding
this rapidly changing industry, please contact Parker’s​
O-Ring Division."

The gist being how much swell and degredation can your design handle.


 
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That was quick though not exactly a ringing endorsment of we designed it specifilcally to be used on pistons and seals LOL.
The brake fluid works for me.
Agreed.

Seriously, I think we can get too wound about the interactions of solvents, rubber, plastic, etc. ...
My favorite is when people warn me about using WD40 on my motorcycle O-ring chains. "The lubrication is not good enough for that use" and "the solvents will eat the O-rings" are the two lines I am always dished. Yet I seem to manage to always get at least 25k miles out of my chains. Go figure.....
And agreed. :yes:
 
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I place a piece of wood in the caliper bracket, then pump the pistons as far out as I dare to effectively clean the whole piston. The thickness of the wood is a trick.
Mellow said:
... so the rotor thickness plus the base of two brake pads should do.. I've seen a bike come in with no pads left and pistons were sticking so maybe add just a hair to that... 1/4 inch..

Good idea - I'm going to put some wood of the right thickness in my home accessory kit. Got to get the measurements...
 
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I noticed that the brake pad retaining pin that Joe is holding in the 3rd photo is missing the O-ring (or quad ring?) that should be in the groove at the end of the pin. The pin from one of my front calipers is also now missing that item - it was in place until after I wiped the crud off the pin. My question: what is the purpose of the O-ring (or quad ring?), and will certain failure of my brakes occur if it isn't there?
 
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I noticed that the brake pad retaining pin that Joe is holding in the 3rd photo is missing the O-ring (or quad ring?) that should be in the groove at the end of the pin. The pin from one of my front calipers is also now missing that item - it was in place until after I wiped the crud off the pin. My question: what is the purpose of the O-ring (or quad ring?), and will certain failure of my brakes occur if it isn't there?
Good catch, forgot about that.. fell apart a while ago and I just kept forgetting to replace it. Not sure of the use but I have to believe it 'should' be there.
 
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I suppose the only true test of whether the seals are EPDM or rubber is to soak an old set in various solvents..... I have heard of Naptha being used to clean pistons/seals with alledgedly good results. It is a slow-acting solvent that doesn't seem to affect much of anything including paint to any degree..... but I see nothing wrong with the brake fluid idea, brilliant actually. I also agree with pushing the pistons out a bit as there can be a "ring"of build up near the outer seal that you can't get with your toothbrush.....
And, Walmart brand brake cleaner will take paint off.... it has MEK in it. Not recommended for anything by me except paint stripping (it does work for that), and it will destroy most rubber/vinyls as it was intended to dissolve them.
 
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Great info, now that I have cleaned my pistons with the brake fluid I notice some rust build up up on the pistons themselves, mainly the harder to reach larger middle piston. I tried to take some pics but they did not turn out. Any advice at this point? Should this rust be knocked off with some Emory cloth or just let go?

Thanks
Greg
 

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Greg,

I wouldn't want to let that score the rubber (o-ring/xyz-stuff)!
I'd cut a used green scrubbie (used because it'll be less aggressive) into 1" strips and use it to 'buff' (shoe shine technique again) that middle caliper.
 
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Is there a write up for removing the front calipers for cleaning/pad replacement?
Not yet, I might be due some front pads before NatSTOC this year so I may pull the wheel and put something together.

However, the calipers are 'basically' very similar so there isn't going to be much difference.
 
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Mellow, Do you take the front calipers off or the front wheel to clean the the pistons?
It's not difficult to take the front calipers off w/wheel still on. 2 bolts on each side.

It is more convenient to do it when you happen to be putting a new front tire on.

If it were me:

1-remove the pin holding the pads in - covered w/rubber plug
2-remove pads
3-remove two bolts to remove caliper
4-clean exposed pistons
5-install calipers
6-install pads

The reason I would remove and install the calipers while still on the bike is-for me-it's just easier to use the rotor to help keep the pads in place and install correctly.
 
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Nice post, thank you. I've only ever put a pile of rags under the caliper and hosed it down with brake cleaner. The gloves are a good idea as the brake cleaner really burns if you get it on you hands. And I've never lubricated those sliders so I'll give that a go next time I have the tire off.
 
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