Manfred
Stuart Brogden
This is the 3rd rear tire I've put on this bike since I bought it. This time, the brake pads do not retract at all when the peddle is released. Could the pins that connect the caliper to the mounting bracket be the problem?
Rear brake drags after tire replacement
- Thread starter Manfred
- Start date
ST1100Y
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- Joined
- Nov 7, 2020
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- 61
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- Vienna, AuSTria, Europe
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- ST1100Y, ST1100R, NT700
Sounds like the pistons are stuck and an overhaul is due...
Over the years the rings swell/crystallization accumulates in the grooves...
Pushing the pistons in all the way during removal of caliper (possible also pushing some dirt in) worsening the issue...
Remove caliper, drive pistons out, remove old rings, clean all thoroughly...
If the pistons show pitting corrosion replace as well, at minimum new set of rings...
Over the years the rings swell/crystallization accumulates in the grooves...
Pushing the pistons in all the way during removal of caliper (possible also pushing some dirt in) worsening the issue...
Remove caliper, drive pistons out, remove old rings, clean all thoroughly...
If the pistons show pitting corrosion replace as well, at minimum new set of rings...
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Manfred
Stuart Brogden
Thank you! I will pursue that course of action.
junglejim
Site Supporter
And inspect the cylinder walls. Maybe polish, or hone, or even replace if necessary.
Upon reassembly replace the brake fluid.
I've seen some so bad I couldn't compress them even with a clamp. Replaced them.
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Manfred
Stuart Brogden
I can push the pistons back into the caliper. See no corrosion on the sides of the pistons. Is compressed air the only way to remove piston? I hate messing with hydraulic brakes.
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Manfred
Stuart Brogden
I removed the caliper, drained the fluid out of it, blew the pistons (had a small board in place to catch them). Everything looks new. Cleaned it all up and put it back on the bike. Now I need to get some DOT 4 and suck air out the caliper.
Replacing OEM bleeders with Speed Bleeders makes brake fluid flush easy. Call them for sizes.
On a recent episode of "The Bearded Mechanic" on YouTube, he used a grease gun, to push the pistons out. Hooked it up to the bleeder valve and kept pumping until the pistons came out. Of course he then had to clean up the grease, but I had to admit, it was very effective.
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Manfred
Stuart Brogden
I have a rubber tip on an attachment for the compressor line. Put that into the hole where the oil line connects and pop-out the pistons with no mess.
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Manfred
Stuart Brogden
I have a device I bought when working on the brakes on my old Honda Sabre. It attaches to the bleeder valve and sucks air and fluid. I add fluid to the master while doing that. Gets air out easily.
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Manfred
Stuart Brogden
Sucked the air out through the rear caliper, added fluid to the rear master cylinder to keep it from sucking air. Have a firm brake peddle (and front brake). The read pistons are still not retracting, causing a serious drag on the disc. I also cleaned the caliper retaining pin.
Attachments
Could the master cylinder compensation port be blocked by debris or the piston not fully returning?
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Manfred
Stuart Brogden
Not sure. I'm thinking I've something not quite right with the wheel and caliper mounting bracket.
Crack the bleed screw. See if it frees up.
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Manfred
Stuart Brogden
I did that early on, to see if a compromised hose was the cause. I ended up removing the caliper from the bike, removing the pistons, and cleaning the caliper and pistons - all of which look new. When I re-installed the caliper, I put a pump on the bleeder valve and sucked air and fluid through the caliper until it was only fluid.
junglejim
Site Supporter
Looks to me like your rotor isn't centered correctly. Check the spacers on your rear wheel. Spacers might be arranged right. .
Another thing is if the caliper slide pins are over greased, the caliper may not center properly. It can maintain pressure to one side. Sort of a vacuum lock. Use just enough grease to coat the pin, don’t pack it.
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Manfred
Stuart Brogden
There's no grease on those pins. I've wondered if they are binding up.
Misc ramblings..... Odd.....you had a working rear brake system before the tire change, correct? Lets assume you put all the pieces back together properly and in the right order and torqued.
So you put on a rear tire and reassembled and now the brakes wont retract, or at least one pad wont retract.
I have always assumed, perhaps falsely, that the way things work is that you remove the rear caliper, take a screw stick, spread the pads slightly, then reassemble.
You get the beast all back together and before you go anywhere, you put the bike on the centerstand and push the rear brake peddle while spinning the rear wheel.
After a few pumps, the wheel should stop turning...then, when you release the peddle, the pads dont really retract....they just dont exert any force. So if one is still exerting force after peddle release, I would try to assertain if it is one or both pads that wont "relax". If its both, the problem has appeared upstream. If it is one, the issue is down stream.
Yes, the pins should be lightly greased. The caliper has to center.
Frosty is right. Speed bleeders are the way to go.
So you put on a rear tire and reassembled and now the brakes wont retract, or at least one pad wont retract.
I have always assumed, perhaps falsely, that the way things work is that you remove the rear caliper, take a screw stick, spread the pads slightly, then reassemble.
You get the beast all back together and before you go anywhere, you put the bike on the centerstand and push the rear brake peddle while spinning the rear wheel.
After a few pumps, the wheel should stop turning...then, when you release the peddle, the pads dont really retract....they just dont exert any force. So if one is still exerting force after peddle release, I would try to assertain if it is one or both pads that wont "relax". If its both, the problem has appeared upstream. If it is one, the issue is down stream.
Yes, the pins should be lightly greased. The caliper has to center.
Frosty is right. Speed bleeders are the way to go.
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Manfred
Stuart Brogden
I'm gonna focus on the caliper bracket and how it interacts with the caliper. These two pins can cause this kind of problem if not functioning properly.