I know what keeps the caliper pistons from retracting on my bike..

John OoSTerhuis

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FWIW, the only lube I'd ever use on the brake caliper pistons and seals is brake fluid. I do use silicone high temp brake grease on the ST1100's single action (pistons on only one side) caliper's sliding pins, as intended.

David, when you R&R the pistons and seals, be sure to remove all corrosion from the recesses that the seals fit in (the common reason pistons bind/don't retract). Be careful to not score the the aluminum with steel tools. Judiciously touching the corrosion with a torch makes it easier to remove. BTDT (thanks, George)

John
 
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SupraSabre

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I just replaced the front pads on my '04#2 over the weekend. One thing I did this time that I never did before was to remove the pad backing plate (or whatever it's called) so I could get in and really clean up the pistons real good, using a tooth brush and brake fluid, this worked great. I then used a C-clamp and a old brake pad to press the pistons back in.
 
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moddy

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FWIW, the only lube I'd ever use on the brake caliper pistons and seals is brake fluid. I do use silicone high temp brake grease on the ST1100's single action (pistons on only one side) caliper's sliding pins, as intended.

David, when you R&R the pistons and seals, be sure to remove all corrosion from the recesses that the seals fit in (the common reason pistons bind/don't retract). Be careful to not score the the aluminum with steel tools. Judiciously touching the corrosion with a torch makes it easier to remove. BTDT (thanks, George)

John
Thanks. Looking forward to getting in there again, with new pistons and seals. It makes sense if you scored the caliper, fluid could leak between seal and the caliper. If this is the case, why did it take so long for fluid to come out if it was scored from having cleaned it previously. We will see. I will inquire as to a couple sources for used left calipers in case I get the same silly leak again. Just trying to go on a 1500 mile road trip soon, that's all.
 

John OoSTerhuis

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An additional thought -- N.B. "brake cleaner" (acetone) is used to clean contaminants off the surface of brake pads and rotors only, NOT caliper pistons and seals. Acetone applied/sprayed in situ will swell the piston dust seal and bind the piston.

I extend my pistons until I see clean shiny surface, and then clean them with Simple Green and/or brake fluid. A strip of very fine 3M abrasive sheet used in a shoe-shine buffing motion works well. If I want/need to rotate the piston to inspect and clean better, I use my tool (posted above).

John
 
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On my ZRX1200, they have 6 pots per caliper. We use a Suzuki p/n because they are the same as the Kaw and cost less. Right about $100 for both calipers. Them some expensive orings IMO...:eek: I just saw what they cost for the ST....wow what a difference, but the ST uses half as many. So with the grease, they slide right in.:)
 
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Haven't had this issue on my ST, but I was advised by a Honda shop once that my previous Honda (88 GL1500) was likely to experience a build-up of crud behind the seal requiring a cleaning every 40K miles or so. Sure enough, they were right.

It wasn't from contact with anything but brake fluid and riding, but this dry goo, slightly gummy, semi-solid crap would build up behind the outer seal and interfered with piston movement. I had to clean out the grooves that the cups ride in also. It left no damage, no etching, no corrosion, and it's the only set of brakes I've ever owned that had this problem.
 
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Roger that! PITA, but it is one of those things ya gotta do. Cleaning the pots when they are extended is good, but ya brake them down every so often (pun intended), split the calipers and clean them up. I just dread bleeding. I might try to pinch off the rear line carefully, get the rear caliper done and back together.....with I hope little bleeding issues.:D
 
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Caliper gaskets arrived today and I rebuilt the caliper. There is a lot of junk that collects under the dust seal. Will likely have to make that a maintenance item every couple of years or so. Can't have the pistons incapable of retracting, can we.
 
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I will provide you guys an answer to what that crud is, you ready for it? BRAKE FLUID! Seriously though it's dried brake fluid, seems to happen a lot on bikes that spend time sitting over winter. If you boil the caliper in water it usually dissolves, but you still have to disassemble the caliper to allow the water access.
 

SupraSabre

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For my last brake job on the '04#2, I took the rear caliper apart (removed the two bolts holding both side together), then thoroughly cleaned all that gunk off the pistons and caliper body, including between the pistons, since I could actually get around them really nice!

Very easy to do! :D
 
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Don't doubt what you are saying. No seal is 100% fluid tight. You may not be able to see the fluid but it will be there, after all that is what must provide the lube for the pistons free movement. Although this is obviously then contaminated with brake dust, road grime, salt, critters etc. If the seal or any seal for that matter was dry they would need replacing with alarming regularity.
Upt'North.
 

jfheath

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Whenever I have my wheel off, I always give the brake pads and the pistons a good clean. Push the pistons out a tad - as John says, until I can see the shiny surface - a wipe to remove the excess crud and then an old toothbrush and brake fluid. I finish off with the sewn hem of a cotton rag, wrapped around the piston and use a drying-my-back motion to clean it up.

When I put the wheel back in, I put the pads in temporarily and pump the pistons out. Then remove the pads and coat the exposed part of the piston with red rubber grease - a silicon compound designed for use on hydraulic seals. I find this to be much better here in the UK where we have lots of rain, often containing salt and water. Yes, the muck sticks to it, but it doesn't seem to get under the seals and the pistons always clean up nice and shiny.

I've only ever had to replace seals once - and that was on my first ST1100, which I bought at 29000 miles and it had been sitting around dirty for quite a long time. Then it took a good bit of time to get the crystals out of the seal grooves in the caliper with bits of sharpened wood and plastic card. The seals that came out were much larger than the piston bore grooves - clearly they had been exposed to petroleum based greases or fluids.

Having said that, my present ST1300 has some niggles. Nothing I can put my finger on, but something isn't quite as it should be. Brakes work fine and they seem to release perfectly OK, but the rear disk takes longer to cool down after the last application of the brakes than I think it should. So in the next few days, it is going to get overhauled. I have a new SMC, I have new seals. I'm just waiting for Santa to deliver my new Motorcycle ramp lift. That should arrive here before Friday. It niggles me because although it has done just under 40,000 miles and came off the production line in 2013, it is an A9 model (A9 was still the latest model in the UK in 2013), and I have no way of knowing how long the components were lying around before they were fitted to the bike.

So I'll report back here in a couple of weeks with what I find - the bike has been ridden in all weathers and all seasons.
 

Whooshka

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Whenever I have my wheel off, I always give the brake pads and the pistons a good clean. Push the pistons out a tad - as John says, until I can see the shiny surface - a wipe to remove the excess crud and then an old toothbrush and brake fluid. I finish off with the sewn hem of a cotton rag, wrapped around the piston and use a drying-my-back motion to clean it up.

.......
This ^^^^

Put something thinner than the rotor between the pads and apply the brakes. Only clean with fresh brake fluid. Doing all 3 calipers should only take an hour.
 
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I had a lot of problems with the rear brake not retracting.i had to put a new disc on the back and noticed that the disc was supported by about 1/4 inch of some kind of cement mix I just took it all out with a small screwdriver and never had a problem since.good idea to clean everything else up while doing this.when you take the disc of just check what it sits on.
 
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I just ordered new seals for the rear caliper. This winter is the right time for a rear caliper rebuild. I have previously tried everything else to get smooth rear pad retraction,, with mixed and partial success. I have never totally eliminated disk drag,,, nowever,, it is much worse when the rear pads are new,,, and greatly improved when the rear pads are almost done (less piston in the caliper). Time to dig deep and take a look,,, Cat'
 
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clean the groves and a light coat of some silicone brake grease on the groves to help prevent any further corrosion.
:plus1: Doing this has eliminated the corrosion problem, especially under the first seal. I had the same problem with corrosion build-up causing the seal to push harder against the piston and causing rear brake drag.

Gotta be real careful cleaning the seal grooves as to not scratch up the surface. On the second groove, that may cause a leak. I use a broken wooden toothpick held by a needle nose pliers to clean the grooves. Slow going, but no scratches.
 
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