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Offline DGTrophy

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Rear brake will not disengage
« on: July 30, 2020, 07:17:02 PM »
Problem With rear brake engaging and not disengaging while I am driving for no reason at all!  I had Do you learn install new brake pads about six months earlier. And then I rode the bike with no issues for about 3000 miles.

Offline Coconut

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Re: Rear brake will not disengage
« Reply #1 on: July 30, 2020, 08:59:15 PM »
The usual cause would be the Caliper Piston sticking and not retracting.

Also, but to a lesser extent as reasons for the brake not releasing,
the Caliper should be free to slide on it's mounting,
and the Pads free to move within the Caliper.

Cheers  :821:




Offline rpeters549

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Re: Rear brake will not disengage
« Reply #2 on: August 01, 2020, 07:36:44 PM »
Like the illustrious Coconut said. 

It is good to take the caliper off, remove the pads, gently depress the brake pedal by hand so you can bump the pistons out just a bit (so you see clean silver piston material).  If only one moves, use your hands to press that one in to force the sticking piston out a bit.  Spray it generously with SimpleGreen or similar and attack all surfaces with a toothbrush (not one you plan to use on your teeth again  :017: ).  Then spray with SimpleGreen again to rinse out the mess and dry it all off with a rag.  I usually then GENTLY spray a bit of brake cleaner in there to be sure all the junk is out.  Be sure to also clean the spring/pins and such.  A small bit of grease on the pins and re-assemble.  I did both front calipers last week, sitting on my butt drinking a barley pop, in a little over an hour so it goes quick.

I also hang an old towel or something over the wheel or parts you don't want sprayed or dripped on.

Prior to putting it back together I also use a small screwdriver and clean out the holes in the rotor, then spray a rag with brake cleaner and wipe off the rotor.

Cleaning the piston sides helps insure they can retract after use, and squeezing the pistons out a bit to clean metal helps insure you do not draw dirt in to the bore which can make it sticky and eventually damage the seal.
« Last Edit: August 01, 2020, 07:38:36 PM by rpeters549 »
Year round rider here!

Offline trophied

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Re: Rear brake will not disengage
« Reply #3 on: August 02, 2020, 02:39:01 PM »
I saw a trick somewhere once using dental floss wrapped around the piston after it was force out just enough to see a clean surface then running it back and forth until the crud buildup was removed.  Looked very quick and easy.
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