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Buell Forum » Old School Buell » Archive through July 21, 2012 » Complete Brake Failure « Previous Next »

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Serialk
Posted on Sunday, July 08, 2012 - 12:03 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

riding around like a hooligan in the city and all of a sudden rear brake pedal drops...like the foot pedal pushed the rod completely in and no rear brake. what so ever
I pull over and inspect. My rear caliper was hot as hell as i inspected i pumped the brake and it started to gan pressure. i waited a few minutes and then hit the hiway to cool shit down without using any brakes. 10 minutes later rear brake is back but there is a fair amount of slack in the pedal/piston to the master cylinder.

sooo my question is... wtf happened and what did I break? any guesses?
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Gmaan03
Posted on Sunday, July 08, 2012 - 12:18 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Use your front brake
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Essmjay
Posted on Sunday, July 08, 2012 - 12:28 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Stuck brake pad maybe? Generating heat and boiling the brake fluid? Just a guess. Might be a good time to disassemble and rebuild the caliper.
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Buell_bert
Posted on Sunday, July 08, 2012 - 06:54 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Ejay I think you got it. Though it may be from (riding around like a hooligan in the city)and the brake was overheated. Either way I would rebuild the rear caliper and replace the fluid. The Quad ring probably was damaged also. OH, and dragging your feet like Mr. Flintstone or tossing out the anchor may help too.
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Ratbuell
Posted on Sunday, July 08, 2012 - 08:38 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Make sure the caliper isn't dragging the pads on the rotor, causing it all to overheat.
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Buellistic
Posted on Sunday, July 08, 2012 - 10:32 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

To avoid MYSTERIOUS brake problems, change your brake fluid once a year weather you think you need to or not !!!
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Ft_bstrd
Posted on Sunday, July 08, 2012 - 12:14 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Your rear brake is only able to generate 30% of your braking capacity. Using it for 100%, is over working it.

Bad fluid. Rear brakes out of spec, dragging pads. I'd be willing to bet hour rear pistons are completely gunned up with dust and aren't properly returning causing your brakes to drag.
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Greg_cifu
Posted on Sunday, July 08, 2012 - 09:16 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

DOT 5 fluid may have a high boiling point but, it also does not absorb water. That doesn't mean water doesn't get into the system. It just means that it doesn't absorb the water...so the water stays as droplets, floating around in the fluid. (and this is why I'm not a fan of the stuff, though you can't just switch because of the seal materials).

So you have small pockets of water inside the caliper (it only takes a drop or two). You get the caliper hot, that water flashes to steam and pushes some of the brake fluid back to the master cylinder.

The next time you apply the brake, you get nothing because that fluid got pushed out of the caliper. Stabbing the pedal a few times pushes that displaced fluid back to the caliper but, now it's spongy (because of the steam). Wait for it to cool back down and it all seems normal again. You scratch your head and wonder what the heck just happened.

As already posted: either flush the fluid and bleed it really well or take it completely apart, clean everything and put it back together. Either way, the goal is to get the small amount of condensed water out of the system and get a good bleed.
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Foximus
Posted on Sunday, July 08, 2012 - 09:28 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

haha. First off. Why are you even using your rear brake.


Second off, its not that bad. I had a front pot on my old PM 6pot caliper get crooked once and lock up, throwing me over the front of the bike and into a 3 car collision. I was in front. All three cars were totalled. I rode home.
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Serialk
Posted on Monday, July 09, 2012 - 02:18 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

thanks for all for the input. Well to answer the main question. I was using my rear brake allot because my fronts are squeeking really bad. I am waiting on new pads as they are glazed over and so is my rotor. I tend to use scotch bright and brake clean on the rotors to rid the squeek as i wait for my pads. well after hard riding for most of the day my front brakes got worse and worse. as result i was using my rear more and more.

The complete loss of braking is something i have never experienced before and how it came back in few moments made me wonder more of wtf happened. going to flush the system first and if its not functioning 100% im rebuilding the caliper. new pads all around are called for
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Natexlh1000
Posted on Monday, July 09, 2012 - 05:13 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

I have found that the footpeg/pedal pivot can get tight due to the frame paint getting roughed up and dragging on the pedal.
If the pedal isn't allowed to return back all the way, the caliper will drag.

Sounds like you have to change the fluid now, check to make sure your pivot is OK while you're down there.
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