Rear brake problems on S2R800. Problem Solved.

[corey]

Hello tech gurus.
I just bled my rear brake on my S2R800. I did all the fancy move the caliper around business, got all the air out, etc. etc.
I have plenty of bite, plenty of stopping power... Problem is, now the pedal is SUPER stiff. I have to push really hard, and the pedal only moves about 1/4 of an inch, and it's full-on, lock up the wheel stopping power...

Any thoughts on how to get that nice, smooth, consistent pedal feel back?
I also have rizoma rearsets. could these be leading to some problems?

[Speeddog]

Do you have any freeplay in the pushrod?

The master requires some freeplay so that the piston isn't covering the bleed hole.
Running with the bleed hole covered will lead to bad things.

[corey]

hmm. not sure.
is the bleed hole located underneath the rubber cover that the pushrod slides into?
there seems to be some freeplay.
what sort of bad things could happen?
would these bad things happen if, say, i were to completely bleed rear brake with said bleed-hole covered?

[Howie]

Do you have any freeplay in the pushrod?

The master requires some freeplay so that the piston isn't covering the bleed hole.
Running with the bleed hole covered will lead to bad things.

Eggzakly what I was thinking.  Not enough free play can lead to a flaming rear brake.  I don't know am exact spec, but make sure the fluid returns (spout of fluid when lever is released) and add a little more. 

[corey]

it appears that here is no fluid returning, but my rear brake is definitely not engaged. wheel spins very freely unless i engage the pedal.
what is the solution for the fluid not returning to the master?

[Howie]

Shorten the push rod until fluid returns, then a little more.  Loosen the lock nut on the pushrod and turn the pushrod until you get the free play.  Ah, found a spec.  At least 1.5mm.

[Popeye the Sailor]

Not enough free play can lead to a flaming rear brake. 

I have had this happen! Do as the man says!

[corey]

will do!
as stated, i did put the new rearsets on.
i will re-adjust the push-rod as needed, and might run through the bleed procedure one more time to be safe. it's not that hard or time consuming.
i wanted to move rearsets back a notch anyway
i'll keep you guys posted!

thanks again for the help, i report back with any further problems.

[teddy037.2]

I have had this happen! Do as the man says!

+1!

DOT4 makes a pretty green flame, if you really want to find out for yourself... 

[corey]

Hah. Sounds cool!
I'd prefer to find out by some other means though. DOT4 Molotov anybody?

[teddy037.2]

Hah. Sounds cool!
I'd prefer to find out by some other means though. DOT4 Molotov anybody?

but half the fun of it is scraping the melted speedo sensor's plastic from your rim... and replacing a whole lotta parts because you didn't put enough slack in the MC's pushy-doo

[corey]

still haven't gotten around to fixing this yet, but i haven't been riding.
i'll be sure that my MC pushy-doo has plenty of slack?
hah.

[teddy037.2]

I ended up backing the rod all the way out on mine (out of paranoia)... I coulda sworn I had enough slack when I installed my rearsets.

[corey]

Well. No luck still after an entire container of DOT4 and a whole lot of swearing.
I even drained the entire system and started from scratch.
Once the system is full, i do a final bleed, close the screw, release the pedal. Then i pump it up for pressure, takes only 1, maybe 1.5 pumps.
Perfect, the wheel stops like a make the beast with two backsing ROCK. But then when i let go of the pedal, the fluid does NOT return to the reservoir. Next time i go to pump the brake, the system is already filled to capacity, and it cannot move more fluid in, so i get instant wheel stopping power in about 1/4" of pedal. Not Good.
No matter what i tried, i could not get fluid to return back to the reservoir.
The hose is not crimped, nothing inside it, i blew through it to make sure. The system is clean, all fresh fluid.
Pressure will release off of the rear brake, but fluid will NOT return.
If i push the pads away from the rotor with a flat head screwdriver, the fluid DOES return. But it will NOT when i just simply release the pedal.

Anyone have any thoughts? I am make the beast with two backsing stumped, i have no clue what to do...
I really want to get on the road

[Bill in OKC]

It sounds like your brake is bled properly.  The problem is like stated above - the push rod needs to be adjusted shorter.  When the brake pedal is released, there should be some free play between the rod and the slave piston.  The piston needs to back out far enough to uncover the internal bleed back port for the fluid to return.  I don't think you'll see a lot of fluid return, not like when you push the pads back.  Does the lever move easily?