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-   -   rear brake problem (http://scsportbikes.com/mechanical-technical/7582-rear-brake-problem.html)

loic May 29th 01:10 pm

rear brake problem
 
my rear brake stay stuck after I push on the well.....brake.. i don't mean that the pads are a little touching, i'm talking about, by hand, the wheel won't spin more than half turn. I cleaned the piston, change fluid etc...
the pad shows excessive heat ( they have a blueish color) also they BOTH have uneven wear, one part of the pads is a lot more used up than other part of the pad.
I can push back the piston without difficulty, but when I do , I hear a pffffffftt by the master cylinder ...

idea off what is the problem ?

GoFast May 29th 01:43 pm

hmmm dirt in the fluid, caliper itself maybe?? try flushing the rear brake

loic May 29th 01:48 pm

I took the caliper appart yesterday, cleaned the piston, seal, replaced fluid.

2upFZ1 May 29th 02:09 pm

You are saying that the pedal is returning once you let off, but the pads stay tight on the rear rotor.

If that is it, bleed the brakes. Sounds like you have some air in the line that is staying compressed. Or some trash in the fluid not allowing the return spring to pull the pads off the rotor.

Bleed them enough to replace all the old fluid.

And while you have the tools out and plenty of fresh fluid, do the front too.

2upFZ1 May 29th 02:10 pm

Doh, see what happens when I get started posting, then have to do some work.

2upFZ1 May 29th 02:13 pm

Oh, and if it still does it after flushing, ziptie a 5lb weight to the pedal overnight, that will allow any trapped air bubbles to work their way up into the reservoir.

ars0n750 May 29th 02:14 pm

air bubbles in the system?

Heres what i would do..

1. take off the rear caliper, not totally remove it from the bike, but seperate if from the wheel.
2.remove pads n shim etc
2a-PUMP REAR BRAKE LEVER TILL PISTONS ARE 3/4 out
3. pop off the top of the res.
4. get some brake cleaner and a big container, spray about 1/3 of the container with the brake cleaner, and then fill the rest up with warm water.
5. Soak the caliper in the container for a good hour.
6.get a brush, something that will get in the knooks and cracks clean them calipers goooood.
7.Wash off calipers really good with water.
8.push the pistons back in the caliper with ur fingers (not hard) Must make sure the res cap is off.
9.clean the rotor real well with the brake cleaner.
10. install caliper pads n shims
11.bleed brakes of air bubbles
12. Easiest way to do this.
a. pump lever like 10 times
b open air bleeder (1 at a time) theres 2 on the rear so becarerfull to do both
c. pump lever again but make sure to keep it held down as u tighten the bleeder valve. let go of the pedal after it has been tightened.
d. Pump lever again about ten times
e.cont with other bleeder till all bubbles are out of the system.
13. Fill res. and put cap on
14. good luck!

loic May 29th 02:16 pm

yeah, the pedal is coming back, no problems, i used 1 bottle of fresh fluid yesterday..
what return spring you're talking about?

2upFZ1 May 29th 02:24 pm

There should be one inside the cylinder. When you push on the pedal, there is a spring connected to the lever to return the pedal, but inside the brake cylinder there is a spring to return the piston and pull the fluid out of the calipers. To release the brake.

First off, what bike do you have?

loic May 29th 02:28 pm

Quote:

Originally Posted by 2upFZ1 (Post 66578)
There should be one inside the cylinder. When you push on the pedal, there is a spring connected to the lever to return the pedal, but inside the brake cylinder there is a spring to return the piston and pull the fluid out of the calipers. To release the brake.

First off, what bike do you have?

a ZZR 1200. so maybe my problems is coming from that cylinder.
also when I pushed the pads away I heard some air ( pfffffttt) coming from the cylinder.
I 'm pretty sure my brake are bleed properly, and I used the mighty vac pump , it's a lot easier...


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