xcdhboy

Just bought a new bike late last year with these brakes...this is the integrated brake/shifter model. I noticed recently that the lever travel for the rear has increased considerably. Braking power is fine, just longer lever travel. That leads me to believe that fluid is not leaving the reservoir to fill the system as the pads have worn down. I spent hours working on the system to troubleshoot. I tried bleeding first...couldn't force fluid through the system from the open reservoir and out the bleed valve by pumping the brake lever...gave up after a ridiculously long time of squeezing the lever. Finally just disconnected the line right at the outlet of the master cylinder, filled the reservoir, and pumped the lever over and over...nothing comes out the exit of the master cylinder! And the fluid level in the reservior doesn't move!

I have to assume this is a defect in the internals. Has anyone seen this before? Is it easy to get at the internals in the lever housing or do I need to just send the unit back to Shimano.

Thanks for help!

xcdhboy

Another question about my brake job. The rear rotors seem to be pretty torn up with uneven wear, even though I've been careful to replace pads. Should the rotors be ground down at a certain point to maintain a flat and smooth braking surface?

veteran_youth

As long as the uneven wear in the rotors is occuring in concentric circles.....DO NOT mess with them. If it bugs you that much, or if the grooves are looking like they might compromise the rotors strength, get some new ones. As far as the MC goes.......that sounds really weird. How is it that the brakes could engage at all if fluid is not being pushed out of the MC?

Anyway, I know from working with Deore 525 hydraulics that working on the MC is a huge pain, and can only assume that it would be way worse with dual control levers. How are you with snap ring pliers in tight spaces? I would recommend taking it to a shop for a look. If they are as confused as you or I (yes I do work in a shop) then send that sucker out.

Andrew

F4iGuy

Did you ever get any help on this issue? I'm having the same problem on the exact same equipment though we've bled the lines, the brake handle is still "mushy" therefore the stopping distance has decreased. Please let me know if you have this one figured out or can point me in the right direction.

tzracer

I have run into a similar problem with motorcycle brake systems.

Without seeing your system it is difficult to tell if the cause is the same.

In order for more fluid to enter the system, the plunger in the master cylinder must be able to fully extend after being pushed inward by the brake lever. I have seen brake levers that did not allow the piston to extend fully. These were fixed by grinding the part of the lever pressing on the MC piston so that when released, there was a gap between the lever and the piston.

The piston in the MC must fully extend to allow fluid to enter the system. An o ring on the piston moves past the bleed hole and seals the system so the brakes operate. If the o ring does not move back past the bleed hole, fluid cannot enter the system.

I would check to see that the piston is allowed to fully extend or you may have blockage in the bleed hole.

F4iGuy

Anyone else?

Az B

It could be a seal in the master cylinder. Those pod shifter/brake lever sets are on sale at Performance for something like $55. If you like them, it might be time to try another set. At that price I wouldn't bother trying to rebuild them... that looks like an exercise in frustration.

Az