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Discussion Starter #1
hey guys i took my bike for a ride today and all of a sudden it felt like i was loosing power and i notice it was my front brakes locking :mad:. the lever also was rock solid and i couldnt pull on it anymore. luckily i carried a wrench with me so i can let some fluid out. i rode to my house with minimal brake power. the next day i bled my front brake system and took it for a ride and see what would happen. after 10 or 20min of riding it happend again. the lever of my front brake is rock solid and its lock. i mustve bled the system at least twice and it keeps doing the same thing over and over. NOW I HAVE NO IDEA WHAT TO DO. if you guys can tell whats wrong with my brakes then i would i appreciate your oppinion and if this problem already happend to you please tell me what you did so i can start riding my 636 again. thanks guys and sorry this is kinna long.

my front brakes only got galfer brake lines and using ebc hh pads.

HELP HELP HELP
 

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did you blead your mc? or just the calipers? do both.... id take the calipers off to see if the pistons are properly working?

when the lever is rock solid can you move your tires/wheel without any excessive slack? if it spins freely then it should poiny you to the MC or lever
 

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Discussion Starter #3 (Edited)
i bled the master cylinder and both calipers. i made sure that theres no air in the fluid. also NO i cant move the bike or front wheel at all when the problem is occuring (so ill get stuck in the road) this had happend for 3 times already and its preventing me from using my bike. i took off the calipers and check if the pistons will push out if i pull the lever and pull back in if i let go of the lever. after checking the pistons it look like its doing its job (working fine) so i dont know whats going on. this sux waaaaaaaa
 

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Discussion Starter #4
anybody else got opinions?
 

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Time to rebuild the Master Cylinder or get another one. Take the lever off and make sure the plunger is fitting into the hole of the barrel of the lever. Also, what type of brake fluid are you using. If you mix Dot 4 & Dot 5, sometimes it will start to crystallize. Get some Motul RBF600 Brake Fluid and flush the whole system with brake parts cleaner first, refill and bleed the system. Ther maybe something stuck or clogging the return of the fluid to the resevoir.
 

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Discussion Starter #6
DOT 5 is not mixable with any DOT brake fluid. Its silicone thats why. i cleaned and used motorex 5.1 to bleed my brake system and same thing still happenin. i did everything and made sure everything should work fine. but this crappy brake system still messin up......i wonder if my pistons is stickin on piston seals inside my caliper.....maybe
 

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Sounds like a problem in the mc.

If both calipers are locked you can rule out a caliper problem, also a hard lever suggests a mc problem. I'm a chicken when it come to fixing brakes so I'd just buy a new mc and upgrade the lines to some stainless.

Well, I guess you can look on the bright side. At least you get an excuse to upgrade your system.

Good luck
 

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Nearly the same thing happened to me just a little while ago. I took my bike out of the storage unit I keep it in and not even a 1/4 mile down the road I went to slow down for a light and when I let off the throttle I felt that my momentum was dying quickly. Dam front brakes locked up. I managed to get my bike over to a parking lot after a few minutes. After about sitting for 10-15 minutes the front brakes released and everything was fine.

This happened once before back in November and the conditions were much like today. Cold then hot with a ton of humidity. I'm thinking some crap from the humidity may have caused my pistons to stick. I'm taking it in my truck to houston this weekend and regardless ofif it happens again or not this may just be the excuse to get those gold pazzos and some ss brake lines.
 

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Discussion Starter #9
how did you fix this problem lonestar? i ordered my internals for the Master Cylinder and all major seals for the calipers and hopefully to put it on next month
 

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how did you fix this problem lonestar? i ordered my internals for the Master Cylinder and all major seals for the calipers and hopefully to put it on next month
Well after the brakes released I just rode around slowly to see if it would happen again and it didn't for 3-4 months so I forgot about it until today. After it happened and released today I rode it about 8 miles home. Luckily a buddy of mine that dropped me off at the storage place was following me. I just got to Houston a little while ago and unloaded the bike from my truck and the brakes feel fine now. I suppose if it doesn't do it again soon I'll probably forget about it until I can get around to getting some levers and then I'll check everything out.

How many miles are on your bike?
 

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Since you are going to be rebuilding the MC might as well take the calipers apart and clean the pistons.

Also when refilling the res don't over fill. When you pump the brakes they are at max extension for the pistons. Some people then fill the res to much and put the cap back on. This does not allow enough room for the fluid to go anywhere and the calipers can not release fully. Only fill just below the full mark.
 

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Nearly the same thing happened to me just a little while ago. I took my bike out of the storage unit I keep it in and not even a 1/4 mile down the road I went to slow down for a light and when I let off the throttle I felt that my momentum was dying quickly. Dam front brakes locked up. I managed to get my bike over to a parking lot after a few minutes. After about sitting for 10-15 minutes the front brakes released and everything was fine.

This happened once before back in November and the conditions were much like today. Cold then hot with a ton of humidity. I'm thinking some crap from the humidity may have caused my pistons to stick. I'm taking it in my truck to houston this weekend and regardless ofif it happens again or not this may just be the excuse to get those gold pazzos and some ss brake lines.
The moisture from the humidity gets absorbed into the brake fluid. When the brakes get hot, the moisture (water) in the fluid starts to boil and causes air bubbles which expand creating pressure in the system which causes the pads to squeeze the rotors..... (pause....inhaling). So completely flush the system with brake parts cleaner, let it thoroughly dry really well (because Brake Parts Cleaner when sprayed is cold, will cause condensation), then refill and thoroughly bleed the whole system. Also make sure your brake lines are in good condition and not dry rotting or cracked due to UV and age. These minute cracks will absorb moisture into the brake fluid. Get some new steel braided lines and always use a New sealed bottle of fluid. As soon as a bottle is opened, it starts to absorb moisture. I've seen water at the bottom of brake fluid bottles that have been sitting on the shelf a while after being opened.
 

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Since you are going to be rebuilding the MC might as well take the calipers apart and clean the pistons.

Also when refilling the res don't over fill. When you pump the brakes they are at max extension for the pistons. Some people then fill the res to much and put the cap back on. This does not allow enough room for the fluid to go anywhere and the calipers can not release fully. Only fill just below the full mark.
Yes, it would be a good idea to dis-assemble the calipers and clean & examine them. Corrosion due to moisture can lead to braking problems.
 

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if both calipers are locking, you need to rebuild the master. crack the bleeder screw on the master to verify this. could be a collapsed line but it's rare on a m/c. mabye whitehendrix will check in & give you some way more useful advice than mine, (or anyone else).
 

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yea that locking up front brake would scare the piss out of me especailly since its unintual(sp?) good idea to stay off till new parts are on
 

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Ive heard of a few people on gsxr's having this problem after replacing brake pads. the two people I know had bad highsides at the track due to a problem similer to this. neither of them have been riding yet so dont know what they did to fix but best to take care of it before something bad hapens
 

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Hey dude, take your brake lever off and look at the piece of aluminum that comes off the bottom of it to trigger the rear brake light switch. I put the same brake lines on and due to the position of the lines, that handle piece hit a line and bent it in a bit when I squeezed the handle, not allowing the lever to fully release (it pushes off the micro switch). This doesn't allow the brakes to fully release. Just a thought because I caught this after I payed a dealer $70 to clean my MC and it didn't do shit. Dealer had no idea what the problem was. I simply bent the handle piece back out a bit. My bike did the exact same thing as yours, problem was simple, but I didn't spot it at first.

Also I was not able to position my lines so the handle tab didn't hit them. I took my MC assembly off and had to remove one of those 2 pieces of metal that locate the stock rubber line (so I could swing the SS ones further over and out of the way).

Let me know if this was your problem. Good luck!

-Brian
 

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Same shit happened again today but they only stayed locked up for a few minutes. I'm gonna check everything out when I get it back up to Shreveport tomorrow.
 

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Over fill of the MC is only thing that comes to my mind to. Fluid gets hot and it will put the squeeze on the pistons cause the fluid can't expand. Mustang90 might have something there too..........don't bring it to a Dealer.....:D
 
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