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Old April 16th, 2019, 09:50 PM   #1
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Mushy rear brake even after bleeding

Hi guys,

As you can see from the title, the my rear brake on my Monster 821 has no stopping power. This is my first bike and I have never worked on a motorcycle before, except for maintaining the chain. The brake pedal goes to the bottom of the travel and does nothing, like literally nothing, I can move the bike with the brake pedal pressed all the way to the bottom. So I watched couple of youtube videos on "How to bleed motorcycle brakes" and bleed the brake as suggested in the videos and the service manual, there were no bubbles after using almost half of the brake fluid from a brand new castrol DOT 4 brake fluid. Even after doing this, it didn't change anything. Do you think I did not bleed the brakes correctly or is there issue I should look at?.


Thank you.

Last edited by manoj517; April 16th, 2019 at 09:53 PM.
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Old April 17th, 2019, 02:09 AM   #2
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1.remove caliper....squeeze pistons whilst removing fluid from reservoir

2.put something between pads to keep them open

3.connect tube to bleeder and press pedal to build pressure...open bleeder and close before pedal hits bottom

4.repeat until pedal becomes firm. be absolutely sure the level stays above the min mark in the reservoir and cycle through the fluid faster than a trapped air bubble....keep the bleed valve pointed up and continue until no air appears...than go a little more...be vigilant that the reservoir does not hit MIN and be quick with cycling...pedal down open close pedal up...repeat

if the pedal goes soft at any point there is still air in the system...a helper adding fluid will go along way...the pedal should tighten up rather quickly but don't stop and don't let the volume go below the min mark

with the pedal taught...seal it all up and go for a ride....ride the brake until the abs kicks in...and keep it up until the pedal turns to mush...then repeat
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Old April 18th, 2019, 03:32 AM   #3
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You absolutely have to take the caliper off and turn it all sorts of directions to bleed it. If you leave it on the bike there's no way you'll get the air bubbles out. You might have to cut the zip ties holding the brake line and ABS sensor to give you enough slack to turn the caliper enough - I had to hold mine at the top of the rotor upside down to get all the air out
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Old April 18th, 2019, 05:06 AM   #4
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You need the bleed screw at the highest point
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Old April 18th, 2019, 06:56 AM   #5
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Quote:
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You need the bleed screw at the highest point
And do it last..
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Old April 20th, 2019, 03:00 PM   #6
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I might be missing something here (lord knows I have in the past) but to my understanding, air in the brake lines leads to brake fade. It sounds like you are starting with no brakes. Have you adjusted the rod that runs from the peddle up to the piston?

I got a 2016 monster 821 in '18 that had 3k miles on it. Soon had problems of the back brakes locking up so the bike wouldn't move. This is a result of air in the system expanding and 'applying' the brakes when I didn't push the peddle. Bleeding the brakes took care of this issue. It removed the air pockets (that expand with heat, unlike brake fluid). It sounds like your brakes are not working to begin with.

Do you have good shoes? Do you have movement of the calipers when you hit the brakes? Does the pressure from the calipers slow the wheel? (sounds like a no, if I read your post correctly). If the pads are not touching at 'idle' and pressing with pressure, you don't have adjusted brakes.

Did that make sense?

lop
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Old April 20th, 2019, 03:26 PM   #7
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Mine was the same as you state (15 got it with 1500 miles recently) brake did literally nothing at all. Searching around seems to be a very common problem. I removed all the fluid from the reservoir (was fairly dark brown). Lengthened the pedal to master cylinder rod a bit as I like the engagement pretty high and then got the caliper nice and high with bleeder as the highest point and then filled the reservoir with new DOT 4 and pumped and bled probably 3 or 4 full reservoirs through the system and now have decent pedal feel and good brakes.

Other option is a vacuum bleeder and pull a bunch of fluid through air and all - if you have a compressor, the bleeder is only about 30 bucks.
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Old April 20th, 2019, 03:27 PM   #8
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Actually the locking of your back brakes is because the pushrod didn't have free play...it closed the circuit not allowing the fluid to return....and as the fluid expanded it pushed the pads into the disc and locked it up ...the mushy rear brake is really common because of the abs circuit compounded by an ill placed bleeder screw
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Old April 20th, 2019, 06:15 PM   #9
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Thank you. I now have rear brakes.
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Old April 22nd, 2019, 07:14 AM   #10
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Thanks for all the replies guys. Sorry for the late reply, I had an accident and broke my right thumb while renovating the deck. It's sad that this happened right before the riding season, looks like I won't be riding for another 4-6 weeks. I'll definitely try to bleed it again with callipers off as you guys suggested and see if that makes any difference.

Cheers.
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Old April 22nd, 2019, 07:33 AM   #11
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Quote:
Originally Posted by lop View Post
I might be missing something here (lord knows I have in the past) but to my understanding, air in the brake lines leads to brake fade. It sounds like you are starting with no brakes. Have you adjusted the rod that runs from the peddle up to the piston?

I got a 2016 monster 821 in '18 that had 3k miles on it. Soon had problems of the back brakes locking up so the bike wouldn't move. This is a result of air in the system expanding and 'applying' the brakes when I didn't push the peddle. Bleeding the brakes took care of this issue. It removed the air pockets (that expand with heat, unlike brake fluid). It sounds like your brakes are not working to begin with.

Do you have good shoes? Do you have movement of the calipers when you hit the brakes? Does the pressure from the calipers slow the wheel? (sounds like a no, if I read your post correctly). If the pads are not touching at 'idle' and pressing with pressure, you don't have adjusted brakes.

Did that make sense?

lop
You are taking incorrect info from different sources and trying to make a statement from it. Pedal adjustment and air in the system are separate problems.
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