 WTF's up with my rear brake?!
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Joined: Mar 2010
Posts: 89
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OP
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Joined: Mar 2010
Posts: 89 |
For a while now I've had a crappy rear brake I had to pump 3-4 times before anything happened. Tonight I decided to investigate and found the rearmost piston seized. So I broke down the whole caliper, freed the piston, greased everything up, reassembled it and refilled and bled the system.
Result? ****** all brake worth speaking off... I can pump the lever as much as I want but I never get anything but the slightest brake where I can still push the bike with my feet.
Any ideas? Remember everything's cleaned and bled worse than a halal goat so it's not that. There is a lot more wear than I would have expected from pads only a couple thousand miles old and it is a little uneven but a prawn cracker would give me more brake than I have right now.
HAYULP!
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 Re: WTF's up with my rear brake?!
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Joined: Jan 2005
Posts: 18,825
"Lighten up, Francis."
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"Lighten up, Francis."
Joined: Jan 2005
Posts: 18,825 |
I can't really help but I just love the imagery sprinkled throughout your post.  
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Re: WTF's up with my rear brake?!
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Joined: Apr 2007
Posts: 3,057 Likes: 8
Loquacious
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Loquacious
Joined: Apr 2007
Posts: 3,057 Likes: 8 |
Bleed the brakes again. There is air trapped in the system. Because the master cylinder moves such a small amount of fluid, you might have to remove the rear caliper and make sure the bleeder screw is at the highest position to let the air escape. Make sure you stick a piece of wood between the brake pads. Agree with the Friar about the imagery..... 
12 Rocket Roadster
03 Bonneville America
69 BSA Firebird Scrambler
73 Yamaha TX 750
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Re: WTF's up with my rear brake?!
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Joined: Jan 2005
Posts: 6,308 Likes: 4
Worn Saddle
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Worn Saddle
Joined: Jan 2005
Posts: 6,308 Likes: 4 |
get a bungie and deploy it on the rear pedal so as to keep the brake engaged fully as possible. Leave this on for 24 hours. This will force any trapped air up to the resevoir, er resavoir, errrr res... ah you know what I mean. Then remove the bungie and top off the fluid. If this does not help enough, do it again. If the brake lines and all the parts are good, this will fix it.
A word to the wise is not necessary. It is the stupid ones who need the advice.
Pat
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Re: WTF's up with my rear brake?!
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Joined: Mar 2010
Posts: 89
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OP
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Joined: Mar 2010
Posts: 89 |
I've given up for the day. Battle will recommence tomorrow!
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Re: WTF's up with my rear brake?!
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Joined: Mar 2009
Posts: 12,964
Stickman Yogi
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Stickman Yogi
Joined: Mar 2009
Posts: 12,964 |
Bleeding that brake can be a beech! I had to take it off and let it hang by the line, then do the bleeding. It took a lot of perseverance but in the end, I won the battle! I can only imagine how colourful the language must have been while working on the brake!!
Live to love, love to live.
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Re: WTF's up with my rear brake?!
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Joined: Jan 2005
Posts: 5,262 Likes: 14
Saddle Sore
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Saddle Sore
Joined: Jan 2005
Posts: 5,262 Likes: 14 |
Ok I'll say it, the brakes on these bike sux. But I still love me Trumpets, warts and all 
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Re: WTF's up with my rear brake?!
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Joined: Mar 2009
Posts: 12,964
Stickman Yogi
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Stickman Yogi
Joined: Mar 2009
Posts: 12,964 |
Quote:
Ok I'll say it, the brakes on these bike sux.
How so? I can lock up both front and back on dry pavement... not saying I'd want to do that (I have btw) but the bike will do it.
Live to love, love to live.
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Re: WTF's up with my rear brake?!
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Joined: Feb 2008
Posts: 2,671 Likes: 15
Loquacious
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Loquacious
Joined: Feb 2008
Posts: 2,671 Likes: 15 |
The front brakes on my 07SM can lock without effort. The tire is the limiting traction factor, not the brakes.
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Re: WTF's up with my rear brake?!
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Joined: May 2007
Posts: 5,068 Likes: 1
Saddle Sore
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Saddle Sore
Joined: May 2007
Posts: 5,068 Likes: 1 |
Been discussed B 4 , but there's a void in these calipers that traps air , thus the neccessity to sorta rotate the caliper some to get the bubble out . Since there's some great imagery on this thread , just imagine Jack in the dark bowels of the Titanic breathing a pocket of air trapped in a bulkhead . Now ya get it . 
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Re: WTF's up with my rear brake?!
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Joined: Jul 2007
Posts: 6,060 Likes: 6
Worn Saddle
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Worn Saddle
Joined: Jul 2007
Posts: 6,060 Likes: 6 |
Quote:
Quote:
Ok I'll say it, the brakes on these bike sux.
How so? I can lock up both front and back on dry pavement... not saying I'd want to do that (I have btw) but the bike will do it.
I've never had any complaints about the braking power, either. I test it at least twice a year with the help of a few stinking deer... 
Fidelis et Fortis
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Re: WTF's up with my rear brake?!
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Joined: Mar 2010
Posts: 89
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OP
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Joined: Mar 2010
Posts: 89 |
The colour of my language? Tartan obviously!
Ran out of brake fluid but it's slowly getting better.
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Re: WTF's up with my rear brake?!
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Joined: Jan 2005
Posts: 5,262 Likes: 14
Saddle Sore
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Saddle Sore
Joined: Jan 2005
Posts: 5,262 Likes: 14 |
Quote:
Quote:
Ok I'll say it, the brakes on these bike sux.
How so? I can lock up both front and back on dry pavement... not saying I'd want to do that (I have btw) but the bike will do it.
Sorry guys, didn't mean to upset the masses with my quote. Please step away from the ledge.
Let’s use the “quote” from the Harley vs Triump thread posted in the lounge, “ I DON’T CARE”
Let me rephrase my statement, BLEEDING THE BRAKES ON THESE BIKE CAN SUX !
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Re: WTF's up with my rear brake?!
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Joined: Apr 2007
Posts: 3,057 Likes: 8
Loquacious
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Loquacious
Joined: Apr 2007
Posts: 3,057 Likes: 8 |
Quote:
Let me rephrase my statement, BLEEDING THE BRAKES ON THESE BIKE CAN SUX !
Pheeeeuuuwwww.....that was close....
12 Rocket Roadster
03 Bonneville America
69 BSA Firebird Scrambler
73 Yamaha TX 750
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Re: WTF's up with my rear brake?!
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Joined: Mar 2010
Posts: 89
Member
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OP
Member
Joined: Mar 2010
Posts: 89 |
Been too busy to fight with the brake the last couple o days but I'm fightin fit and ready to go toe to toe with the sob tomorrow!
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Re: WTF's up with my rear brake?!
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Joined: Mar 2010
Posts: 89
Member
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OP
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Joined: Mar 2010
Posts: 89 |
Yep, back to this again. Brake still no damn good... been all over it and there's no leaks and I've put litres of fluid through it and made sure there's no air in there and I STILL have to pump the pedal 3-4 times before I get any bite. I've had an idea though. Can't remember whether I admitted my shame of hastily sticking the rear pads in the wrong way round or not but it had the result of jamming one of them onto the disk. Obviously this created hellish amounts of heat so I'm wondering could the heat have screwed up one or both of the pistons? One of them is determined to stick regardless of what I do. Replacing the pistons, seals and yet another pair of pads is the only thing I haven't done! If this crap goes on any longer I'll be able to publish a saga to rival Lord of the Bleedin Rings! On a positive note, my wrench throwing arm's about ready for the big league  Oh aye, Goldfren pads suck.
Last edited by Ronz32; 08/18/2011 8:58 AM.
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Re: WTF's up with my rear brake?!
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Joined: Feb 2007
Posts: 23,171 Likes: 55
Fe Butt
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Fe Butt
Joined: Feb 2007
Posts: 23,171 Likes: 55 |
Put a micrometer on the rear disc, if you rode it that way and created that much heat you may have worn the rotor too thin. Also check for warping, if warped enough it could be pushing the pads too far back for the throw of your master.
I learned all I need to know about life by killing smart people and eating their brains.
Eat right ,Exercise ,Stay fit, Die Anyway!
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Re: WTF's up with my rear brake?!
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Joined: Mar 2010
Posts: 89
Member
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OP
Member
Joined: Mar 2010
Posts: 89 |
Quote:
Put a micrometer on the rear disc, if you rode it that way and created that much heat you may have worn the rotor too thin. Also check for warping, if warped enough it could be pushing the pads too far back for the throw of your master.
Worth a shot, tried everything else.
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Re: WTF's up with my rear brake?!
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Joined: Mar 2005
Posts: 1,284
Learned Hand
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Learned Hand
Joined: Mar 2005
Posts: 1,284 |
I have been trying to post all morning but work has been hell so I keep getting timed out on my screen. Ian is absolutely right about a warped rotor being a possible cause but that would only cause a soft pedal after you rolled the bike a few feet, your initial pedal would be fine. I don't hear you saying anything about rolling the bike and you were honest enough to admit the buggery of the pads, so I think it's something else. It sounds like your caliper has one piston which is still seized and , if that is so, that is your problem. The pistons only move ever so slightly with each application of the pedal. If only 1 is moving, it is fighting against the other and never allowing the pads to reach their equilibrium possition ,just off the rotor, and ready for the next application. Each time you hit the pedal it is like the first application of a fresh front brake job in an automobile, ( we've all experienced that "Holy Crap" moment when we realize we forgot to pump the brakes back up). Free up your caliper pistons and you'll be good, that's my final answer. Aren't you the guy who referred to our fugly front indicators as "flourescent scrotums"? I'm still laughing. 
Strangler
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Re: WTF's up with my rear brake?!
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Joined: Feb 2007
Posts: 23,171 Likes: 55
Fe Butt
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Fe Butt
Joined: Feb 2007
Posts: 23,171 Likes: 55 |
Paul, wouldn't a seized piston cause the pedal to need less travel to reach full pressure?Needing less fluid to fill the single piston area?
I learned all I need to know about life by killing smart people and eating their brains.
Eat right ,Exercise ,Stay fit, Die Anyway!
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Re: WTF's up with my rear brake?!
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Joined: Mar 2005
Posts: 1,284
Learned Hand
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Learned Hand
Joined: Mar 2005
Posts: 1,284 |
Quote:
Paul, wouldn't a seized piston cause the pedal to need less travel to reach full pressure?Needing less fluid to fill the single piston area?
That would be too simple. It's more about the piston that's moving contacting the rotor and twisting the caliper out of parellel with the rotor since there's still space between the other edge of the pad and the rotor since the piston isn't moving. I'll bet the pads are worn at an angle. If the piston is seized it needs to be freed up anyway, I'll bet a nut that solves it.
Strangler
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Re: WTF's up with my rear brake?!
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Joined: Mar 2010
Posts: 89
Member
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OP
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Joined: Mar 2010
Posts: 89 |
The pad IS worn at an angle but I've freed the piston 2-3 times now. Think I might need new seals and pads at least.
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Re: WTF's up with my rear brake?!
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Joined: Feb 2007
Posts: 23,171 Likes: 55
Fe Butt
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Fe Butt
Joined: Feb 2007
Posts: 23,171 Likes: 55 |
Quote:
Quote:
Paul, wouldn't a seized piston cause the pedal to need less travel to reach full pressure?Needing less fluid to fill the single piston area?
That would be too simple. It's more about the piston that's moving contacting the rotor and twisting the caliper out of parellel with the rotor since there's still space between the other edge of the pad and the rotor since the piston isn't moving. I'll bet the pads are worn at an angle. If the piston is seized it needs to be freed up anyway, I'll bet a nut that solves it.
Makes sense.
I learned all I need to know about life by killing smart people and eating their brains.
Eat right ,Exercise ,Stay fit, Die Anyway!
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Re: WTF's up with my rear brake?!
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Joined: Mar 2005
Posts: 1,284
Learned Hand
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Learned Hand
Joined: Mar 2005
Posts: 1,284 |
Quote:
The pad IS worn at an angle but I've freed the piston 2-3 times now. Think I might need new seals and pads at least.
Generally, a quick hone, new seals and boots and the caliper will free right up. However, if it keeps seizing up, maybe a new caliper is in order. I think the pads are the same front to rear so I wonder if the calipers are the same. Ebay?
Ha, ha, ha, flourescent scrotums, never gets old!
Strangler
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Re: WTF's up with my rear brake?!
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Joined: Mar 2010
Posts: 89
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OP
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Joined: Mar 2010
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I'm hoping not to have to replace the caliper but if it comes to it I might just upgrade both ends while I'm at it.
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Re: WTF's up with my rear brake?!
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Joined: Jan 2005
Posts: 11,124 Likes: 13
Should be Riding
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Should be Riding
Joined: Jan 2005
Posts: 11,124 Likes: 13 |
First, the front pads are different than the rear pads. Second, the calipers therefore are not interchangeable between front/rear wheels.
PinWall Cyles (fleabay) usually has used calipers. I got a rear one for $53.98 delivered and installed it no problem about 14,000 miles ago. Do make sure you either anneal the banjo washers or get some new ones if you remove the caliper. If you upgrade you are looking at the high end of 3 figures. (for one caliper).
Blowing gravel off rural roads
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Re: WTF's up with my rear brake?!
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Joined: Mar 2005
Posts: 1,284
Learned Hand
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Learned Hand
Joined: Mar 2005
Posts: 1,284 |
Don't upgrade, caliper can't be too much on Ebay. My dealer says the pads are the same but I'll bet Moe's correct. The only reason I wonder is because front calipers are a dime a dozen.
Still, I'll bet pistons and seals and a new set of pads will solve your issue.
Strangler
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Re: WTF's up with my rear brake?!
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Joined: Mar 2010
Posts: 89
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OP
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Joined: Mar 2010
Posts: 89 |
OK after some research, screw upgrading. Prices are scary!
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Re: WTF's up with my rear brake?!
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Joined: Aug 2009
Posts: 1,474 Likes: 5
Learned Hand
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Learned Hand
Joined: Aug 2009
Posts: 1,474 Likes: 5 |
'04' Black America
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