rear brakes sticking on 2000 SV650?

Hi All,

i just replaced a leaking rear master cylinder on this bike, and since
then ive had a couple of panic stops in traffic.

both times, the rear wheel locked up, but STAYED locked up even after
i removed my foot from the pedal, then released spontaneously maybe 3 to
5 seconds later.

the new rear master cylinder and pedal appear to be in perfect condition.
the pads are pretty thin and im thinking maybe one of the caliper
cylinders is jamming because its close to the end of its travel?? any
ideas? ive already ordered new pads.

 

thanks, sounds like worn out pads and/or corrosion..

 

Make 100% sure the new master cylinder isn't binding due to being installed
wrong. The only thing you touched is pretty likely to be the culprit if
you haven't changed anything else...

That said, it's not unknown for calipers to jam up due to corrosion,
especially if you've ridden in the winter and gotten salt on the caliper.
I'd take off the caliper, strip and clean and reassemble. If you find any
hint of corrosion, I'd do the same to the front calipers as well.

 

Uncover the relief port and it should be back to normal. Pretty usual
if you screw the linkage in too far.

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'01 FXDWG, NTXNS
"Happy Hour" starts one twist of the throttle past neutral!
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On Thu, 19 Aug 2004 17:15:46 -0500, Page wrote:

huh? whats the relief port? are you describing something on the master
cylinder or on the caliper?

 

It is in the master cylinder. If you noticed when you pulled the
plunger out, there was a tapered spot on the shaft followed by an rubber
seal. The relief port is a tiny hole in the reservoir that allows the
fluid to return to the reservoir when the handle is released. If the
plunger is slightly pushed in because the cable is too tight or the
linkage is screwed in too far, it blocks the hole and doesn't allow the
pressure to release the calipers so the next time you squeeze the handle
the calipers keep getting tighter and tighter until it locks the wheel.
The spring in the master cylinder could also be weak. The only thing
that causes your calipers to retract when you let off the handle is the
seal. When the piston in the caliper is pushed out by the hydraulic
fluid it distorts the seal outward. Since it is rubber, when pressure
is relieved then the seal goes back to its neutral position pulling the
piston back with it. So, if the pressure is never relieved, then the
seals never have the chance to pull back. This will cause the
conditions you described and pre-mature brake pad ware. Left set long
enough, the fluid will slowly be pushed back up into the reservoir.

Take the top off the reservoir, work the brake, you should see a little
spurt of fluid coming back up into the reservoir with each pump as you
release the brake. Be careful though the brake fluid will eat through
any paint it gets on in a hurry, I don't think you can wipe it up fast
enough, unless you are using DOT 5, it shouldn't hurt the paint.

The relief port could also be clogged. Spray compressed air through it
to clear the blockage.

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'01 FXDWG, NTXNS
"Happy Hour" starts one twist of the throttle past neutral!
Remove the 123 to reply.