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Sticky Brake Problem

Dear All, please read carfuly before replying as one liners proberly wont be helpfull.

Sometime ago i mentioned in at thread that i had been through 3 sets of brake pads in 12000 miles (now nearly 4), it turns out that for about a a year i have has a sticking front brake caliper.

This was flagged up at the yearly motor inspection, before i took it i changed the front pads as they looked a little low and noticed the pads dragging, i do not know for how long before this this problem started. I first thought it was just needing a little time for the pads to wear into the shape of the disk.

As the bike failed the inspection on a dragging front brake, the tester suggested to clean out the caliper grouves where the seals are and lube the pistons with read rubber grease on reassembly.

Well after stripping the caliper down cleaning the near spotless pistons and seal grooves all looked good. The ABS system was a pig to bled, i tried pumping, suction and even back bleeding with a syringe full of fluid, eventually mounting the caliper on a frame so it was higher than the master cylinder helped, but i still think it could be better.

This improved matters but the brake still dragged a little but was good enough to pass the test for another year.

I have disassembled the brake and caliper carrier mounting several time and it appears that the caliper and carrier are jamming on the pins. These pins have been polished and the inside of the caliper polished, and move freely when greased and test fitted, but only jam after use.

There is still slight drag on the disk and it is starting to look a bit rough, after a 10 minute ride the disk and caliper are very hot and on disassembly the pins have stuck so the caliper won't slide.

The pistons can be pushed back in the caliper with you thumbs under moderate presure so i dont suspect a faulty brake hose or seal not raleasing the fluid, however when pressing the brake lever the pistons move out but dont appeare to retract slightly which is the thing im expecting to happen.

Now completly out of ideas, and arbetrellary changing the disk, pads, caliper and carrier is not an option and far to expensive at present.

Please read carefully before replying, currently cant take it to a dealer as i'm paying for my sons wedding and properly for the next few months.

Any similar experience in this type of problem would be appreciated, i don't want to sell it cheap just to be shot of the problem as i still want to use it as a winter bike when the Duke is resting.

Thanks

If you want pictures of anything i'll have to reply after i have taken them.
 

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It sounds like you have covered all the obvious possible causes.

At this point I would look at the master cylinder. Maybe there is an internal issue that is causing pressure to build, not allow fluid to flow back freely, or not allowing the plunger to return 100% when the lever is released. I guess I'd see if there is a rebuild kit available, and clean/rebuild it.

It's also possible the additional ABS equipment could be causing the problem, but I'm not that familiar with the system.
 

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agree on thorough investigation/cleaning etc,
so upstream [jkv mentions master cylinder]
also brake lines,, and perhaps inboard
to disc integrity..
'very hot' would influence upstream
incl fluid etc, also inboard, disc/rotor etc..

at least you achieved some improvement..
now aside from mechanical/hydraulic factors,
'very hot' is itself causative..
 

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@lemmy99 I have a cbr 250r abs version. I just ran into the same problem as u did . I have changed all the o ring, brake pad etc. But i still have the brake dragging. Have u solved the problem?Plz let me know . As our friend @jkv357 said The problem may be the master cylinder. Will try to replacing it.
 

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@lemmy99 I have a cbr 250r abs version. I just ran into the same problem as u did . I have changed all the o ring, brake pad etc. But i still have the brake dragging. Have u solved the problem?Plz let me know . As our friend @jkv357 said The problem may be the master cylinder. Will try to replacing it.
If the piston moves freely, the sliding "pins' are the most common cause of dragging. The pins need to be cleaned and old grease removed, then re-greased with a suitable synthetic high temp grease or caliper lube. Do not use standard grease. Clean all the old grease out of the rubber boot as well. Make sure the caliper halves slide smoothly on the pins before installing.

A problem with the mastercylinder is possible, but the sliding pins and piston/seal of the caliper are a much more common cause of brake dragging problems.
 
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