Article [13] ST1300 - Rear Brake Piston Cleaning

I was putting a tire on the bike and decided to do an article on how I clean the rear brake
whenever I do a tire change.

If anyone has more info to add, please post and I'll adjust this article.

Okay, let's get to it.

1. This article assumes you've already removed the rear wheel
2. Remove the rubber plug that covers the bolt on the rear caliper
   
   
   
3. Unscrew and remove the caliper stopper bolt that holds the pads in
   
   
   
   
   
4. With the bolt removed, remove both pads
   
   
   
   
   
5. Once you remove the pads, the forward clip may fall out - no problem, it's normal
   
   
   
6. Here, you can see the pistons but the bracket is still in the way, let's slide it away from the caliper to have more room to work
   
   
   
   
   
7. Now, you can really see the crud on the pistons. I do this every rear tire change and these have about 6,500 miles since the last cleaning. I also do this whenever I put in new pads as they pistons will be extended about as far as they'll go.
   
   
8. Cleaning - okay, needs some DOT 4 Brake fluid and a soft toothbrush
   DO NOT USE BRAKE CLEANER - IT WILL DAMAGE THE SEALS
   
   
   
9. Brake fluid is very corrosive so use gloves and don't get any of this stuff on your skin, more importantly, don't get any on your paint.
   
   
   
10. LIGHTLY brush the area around the pistons, no need to scrub them hard or push between the piston and the caliper as there's a seal in there and you don't want to compromise that, the brake fluid will take care of a lot of the crud. Finish up with a rag to clean up the area.
    
    
    
    
11. Here's the bracket and the clip and where it should sit - the manual states silicone grease should be used on the sliders that connect this bracket to the caliper - there's a male and female connection on the bracket and corresponding ones on the caliper.
    
    
    
12. Here is the bracket back on the caliper and the clip highlighted, note the nice clean pistons.
    
    

Nice job on making it look easy with some great photos!!

Excellent article and pics Joe..thanks

+3
You can do my tire changes *any* time!!!

Stealth Maintenance: Never even thought of this before, but it seems to make perfect sense.... Thanks very much for sharing.

Good show. Added tip, if you don't have a toothe brush us a microfiber rag and cut it int 1 inch strips. This way you can get the stripes around the pistion and buff it like you are shining shoes.

Yep, nice pics & write-up. I too use the rag shoe-shine method.

Great job Joe. Really appreciate the time you took to explain and illustrate the process.

Thanks for this - great info. Much appreciated.

Scotch brite nylon scuff pads work too, cut to 1/2 inch strips. For the really cruddy pistons. Brake cleaner works well, avoids the issue of brake fluid on paint, dries quickly.

bkra13 said:

Brake cleaner works well

Click to expand...

Not good for anything near plastic so I would say not to use that. Might dry up the seals.

Mellow said:

Not good for anything near plastic so I would say not to use that. Might dry up the seals.

Click to expand...

I think I recall that it makes rubber swell. Which would eventually stop the square one from retracting the piston.

Bigmak96 said:

I think I recall that it makes rubber swell. Which would eventually stop the square one from retracting the piston.

Click to expand...

Thank you sir..

??? sorry, I'd have to disagree. It's used in every shop to clean off rotors, calipers, drum brakes, etc, etc.. I've used it on all my cars, bikes, never an issue. Seals are rubber anyhow, not plastic, and none of the brake cleaners carry any warning about damaging rubber.

Excellent guide sir, I clean my calipers every tyre change also and if they look particularly dirty between services.... or pad changes.

Good pictures too!

The dust seal and piston seal are compatiable with brake fluid duh LOL. So... they are probably epdm sometimes called "rubber"
Manuall says lube dust seal with brake grease not grease. Makes sense as epdm is not compatible with motor oil or grease.
(silicone grease aka brake grease aka dielectric grease)

CRC brake cleaner non chloronated contains toluene. This is not compatiable with epdm.
CRC cholornated (if you can find it) contains tretrachlorethante and trichlorothene. Neither is compatible with epdm.

O rings in other places are likely buena-n also called "rubber" which is compatible with motor oil or grease and not compatible with brake fluid.

brake cleaner is a great degreaser and remover of brake fluid which shouldn't be on your disks or pads.
brake fluid is a great cleaner compatible with the dust seal and piston seal.

Great article Joe! :clap2:

I cleaned my pistons the last couple of times of replacing the pads. Especially when I replaced my pads the time before last and the pistons were sticking due to crud build up which caused me to wear down my rear brake more then I would have liked in just one commute.

The only thing I would change would be the tooth brush...I like Oral B...

Hmm, seems to be another "oil" type topic.. Some use it, some don't. Shot an email to CRC, makers of Braklean, about the subject of Brake Cleaner and EPDM. Curious to see what they say. Most references to toluene causing problems relate to soaking the rubber over an extended time - brake cleaners pretty much evaporate within 10 or 15 seconds.

That will be interesting to hear what they have to say.
Parker, the folks who make o-rings says no. Well their tech info anyway.
But compatibility means differenct things for different application.
swelling, crazing, hardness, elasticity, surface properties etc...

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.