mushy rear brakes

[JustHoward]

While replacing my rear tire, we also replaced the rear brake pads. Immediately after putting the caliper back on, the rear brake became soft, and the travel of the pedal was much more than it had ever been. Thinking that somehow air got into the system (I can't imagine how), the mechanic bled and rebled and rebeld the rear brake system, but the brake pedal still has a long travel and the brakes are mushy.

What's going on? Help, please.

Gen II, 95,000 miles.

Howard

 

[Chuck35]

Bleed the front too, they are linked.

edit: I should say, pump the rear and open the front bleeders, one of them is from the rear (i forget which). Then bleed the front.

My bike had spongy rear pedal when I got it. PO never used rear brake lol. They stayed spongy till I did the front bleeder.

 

[HotRodZilla]

The lower right front is the caliper linked to the rear. However, I'm betting that's not your problem.

It is pretty easy to put the rear caliper on incorrectly so that both pads are one side of the disk. This is usually accompanied by an ugly noise. I would take the caliper set off and reinstall it.

 

[JustHoward]

Both pads are installed correctly, one on each side. The front brakes work flawlessly. How will bleeding the front affect the rear, and why should this occur just at the same tire as replacing the rear brakes?

 

[odot]

Awww.......linked brakes.....the scourge of the "next" generation....oh, wait, they have a whole slew of other scourges....um......scourgi?....um.....nevermind.

 

[wfooshee]

One of the things that has to happen with a pad replacement is squeezing the piston back into the caliper. Then once everything's all buttoned up the brake is applied to squeeze the brake pads back down onto the disc. It takes a few pumps to reseat the pads. Until then, the brake will have no resistance at the pedal, and there will be no rear brake.

That did get done, didn't it?

The other thing that pushing the piston in does is return all the nasty fluid into the line, and back into the master cylinder, stirring up any water that may have been absorbed. A thorough bleed will flush the system with new fluid.

The lower piston on the right side of the front is actuated by the rear brake pedal, thus "linked" brakes. The rear works a little bit at the front as well. If that one didn't get bled at the same time as the rear, then bleeding may as well not have happened. (And you bleed that one by pumping the rear brake pedal, not the front lever....)

Lastly, who made the pads? Are they Yamaha OEM or something else? Different pads can easily have a much different feel.

 

[rbentnail]

Lastly, who made the pads? Are they Yamaha OEM or something else? Different pads can easily have a much different feel.

This.

 

[road runner]

I had the same thing happen this spring, and still haven't fixed it yet. Mine , the travel seems just a little more , but the rear brake seems week, and pushing the pedal kind of has that wooden feel.

When applying the rear brake the bike nose dives like only the front unified brake is working. Both the front and rear are working, just the rear is week.

I bled the system several times and still no love. The ABS is working. I checked the pressure coming out of the ABS pump and it was OK. So that leaves the rear proportioning valve, and the caliper . I'm thinking that when the caliper piston was moved back and forth pushing fluid both ways, maybe, somehow the proportion valve got stuck in the low pressure position. Or somehow the caliper is not working, although it seems to be working just fine.

I'd like to check the pressure at the caliper to see if it's the same as at the ABS outlet. That will tell the story.

 

[JustHoward]

Splurt!

Splurt!

That's what my mechanic said he heard when he bled the right front piston by pushing on the rear brake pedal. The were two healthy squirts of air, and then good clean fluid. Now the brakes work (he tells me).

Once again, the wisdom of the list prevails.

Thanks to all of you for your help.

Howard

 

[wabill]

Same issue with my 2010 and even had a shop check it out while on the road say that it was fine. NOT! After new fluid AND a very thorough rear brake system flush and bleed the rear brake is back to normal. Love this forum.