Author Topic: Brake pedal low  (Read 1513 times)

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Offline Sunchaser

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Brake pedal low
on: October 08, 2019, 04:37:33 PM
My rear break pedal is suddenly way low.  It will still apply some force, but way down at the end of the stroke.  Reservoir is low, but above the ďminĒ line.

Bike is a 2016, 6,500 miles, always garaged, never down or abused.  TIA for thoughts...
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I am NOT a Biker, nor a Hooligan, Iím a Motorcyclist.

#1

Offline starpower

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Re: Brake pedal low
Reply #1 on: October 08, 2019, 04:53:17 PM
I would top off the res. for starters, check pads (would be odd at this mileage). Past that it could be a bad seal.
"The most beautiful things in the world are those from which all excess weight has been eliminated" - Henry Ford I, 1893

#2

Offline Sunchaser

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Re: Brake pedal low
Reply #2 on: October 08, 2019, 08:59:56 PM
Topping off will be the first thing I do, as soon as I get my jacks out from under my sonís Fireblade.  Heís replacing his tires and my garage is a mess.

I have a 911 and will review any error codes etc. too.

Thanks
2016 BMW S1000R, I likes 'em naked.
"BMW - The Ultimate Driving Riding Machine!"

I am NOT a Biker, nor a Hooligan, Iím a Motorcyclist.

#3

Offline Sunchaser

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Re: Brake pedal low
Reply #3 on: October 14, 2019, 07:45:23 PM
Also, while up on the jack, the front lever had no effect while the wheel was spinning and lever applied.

Turns out the fluid level was plenty high, but ugh!  Brake fluid very dark and ugly.

Drained the reservoir and removed the cylinder.  Researching what to do while waiting for a Haynes manual.   Must be a rotted seal or something in the cylinder.  Kinda disappointing, never had a rear cylinder issue in 50 years of riding.



2016 BMW S1000R, I likes 'em naked.
"BMW - The Ultimate Driving Riding Machine!"

I am NOT a Biker, nor a Hooligan, Iím a Motorcyclist.

#4

Offline starpower

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Re: Brake pedal low
Reply #4 on: October 15, 2019, 04:27:57 PM
It is amazing that the fluid could get that contaminated in just 6500 miles. A disintegrated seal?
"The most beautiful things in the world are those from which all excess weight has been eliminated" - Henry Ford I, 1893

#5

Offline Swampwhore

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Re: Brake pedal low
Reply #5 on: October 16, 2019, 09:13:20 PM
I just had the same issue. Flushed with new fluid and now all is good.  I think the humidity in Florida is part of the problem. Usually the front brake lever goes soft on me before the rear. A quick bleed at the master cylinder fixes it, but shortly after I start noticing water droplets in the reservoir (I have a clear Rizoma reservoir).  If I just do a manual bleed I get maybe 6-8 months before I get a soft lever. A full flush per the manual using the GS-911WIFI gets me about a year before things get spongy again.  I have two other bikes I use regularly and I havenít touched the brakes on either of them in several years with no issues.  (Guess I should flush both of them this weekend)  Just the R gives me issues.
Twist the right grip until you see G*d....then back off...just a little bit.

#6

Offline Sunchaser

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Re: Brake pedal low
Reply #6 on: October 16, 2019, 09:49:08 PM
Thanks for the input. 

Flushing and reloading is basically my starting plan.  That rear reservoir is impossible to access, someone at BMW needs to go back to design school.  Always fun learning a new bike.

You ever get West to the coast, look me up.
2016 BMW S1000R, I likes 'em naked.
"BMW - The Ultimate Driving Riding Machine!"

I am NOT a Biker, nor a Hooligan, Iím a Motorcyclist.

#7

Offline Swampwhore

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Re: Brake pedal low
Reply #7 on: October 17, 2019, 12:54:38 PM
I take out the bolt holding the reservoir in place, pull it out, then tie it to the frame when I bleed. 

I got to thinking about it, and I have been using high dollar Motul fluid in the BMW.  In mother bikes, car, truck, I use whatever is cheap at the parts store.  I'm guessing the Motul (higher temp) is more likely to attract water than the other stuff.  Next time I flush, I'm going to give theater stuff a shot and see if it buys more time for me.  I probably don't get the brakes anywhere near hot enough for it to matter most of the time.
Twist the right grip until you see G*d....then back off...just a little bit.

#8

Offline Sunchaser

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Re: Brake pedal low
Reply #8 on: October 17, 2019, 04:10:50 PM
*Originally Posted by Swampwhore [+]
I take out the bolt holding the reservoir in place, pull it out, then tie it to the frame when I bleed. 

Presactly what I had planned to do.  Good to know it works.  My average speed is about 18mph since I donít stray too far from the beach anymore, so I donít worry too much about fluid temps.
Last Edit: October 17, 2019, 04:15:40 PM by Sunchaser
2016 BMW S1000R, I likes 'em naked.
"BMW - The Ultimate Driving Riding Machine!"

I am NOT a Biker, nor a Hooligan, Iím a Motorcyclist.

#9

Offline beech

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Re: Brake pedal low
Reply #9 on: October 19, 2019, 06:18:50 AM
SC, one of the guys above hit it, the high humidity in your location contaminated your fluid. I suggest you change it annually. Even though you only had 6500 miles, you have 3 years on that stuff, way past due. Now change the front. Don't forget to press the pucks back to allow for fresh fluid to go in there. You can see the brake line has the bleed nipple on top and it is a straight bypass if you don't follow the shop procedure.