Why does my front brake drag?

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#1
I have a 2000 YZ-250, the front brake is dragging. I removed the lever and the top of the master cylinder and it still drags. I believe it is NOT a hydraulic issue. I'm going to pull the caliper off and look at it (and thus also eliminate a dragging front wheel bearing or crap in it).

Ok, I pulled the caliper off, it spins fine with no caliper on it. I tried to slide the caliper on and hold it in my my hand, not bolted on, and it drags like crazy, I really had to SHOVE it on there. I cleaned off the disc with contact cleaner and examined the pucks, nothing weird there. It's like they're either too big or shoved in too far.

Thanks
 
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IrishEKU

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#2
Water in the system, more importantly in the caliper. Another issue could be the boots around the cylender are torn and allowing water in. This will then cause the rods to rust and bind, thus not allowing for smoth brake operation. Question, constant or partial? By partial, I mean only at certain points on the rotation of the tire, if it's that you have a tweeked rotor and a sticking caliper.

Phillip
 
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#3
Thanks for replying.

It's constant. I put a piece of tape on stand and got in front of it and spun the tire. The disc doesn't appear to be bent or warped.
 
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#4
I'd bet those pins are rusty. Have your brake pads worn evenly on both sides?? At the shop I work at we get street bikes all the time where one pad is practicly brand new, the other one nothing left, and sure enough the calipers are froze every time.

take the caliper off again and make sure that the piston is free floating...those can also become sticky and not allow the brakes to release properly.
 

IrishEKU

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#5
Sounds good!

Pull your caliper and check it carefully. Bleed the system, change the shoe's and work brake cleaner into the pistons. Keep an eye on the piston covers for holes or tears, that's where your contaiminants will work their way in. Personally I would replace or rebuild the caliper, but buying new doesn't hurt either. Since your bike is fairly new, try bleeding the system and replacing the pads while placing close attention to the boots around your pistons. Also from here on out take close care in checking your rotors, if you ride in muddy conditions your rotors will fill with mud and lodge in the cooling holes, it causes heat build up on the rotors and added grainuals to collect on the surfaces that are susceptible to failure much faster than steel.

Good Luck,

Phillip
 

marcusgunby

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#6
I think there is a return bleed in the master cylinder that can get blocked with crud and this will not allow the pistons to retract.
 
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#7
I took the caliper off and apart and learned a lot. I cleaned it all up, plenty of brake cleaner and cleaned up what I could on the wire wheel. The pin is now nice and shiny. It appears to float freely now (I can grab the caliber and move it slightly left and right. That's good, I hope). The pads were worn evenly and now that I have everything back together, the pads don't drag anymore. I wasn't able to get the pucks to move at all, even after pulling the bleed valve. I'm not sure what that means. I have no compressed air to remove them as the crappy Yamaha manual (need another Clymer manual) instructs. The bike would brake OK before, but it wouldn't release all the way. I hope that by cleaning everything up and ensuring that the pads are ok, I'll be ok after bleeding them. But that's another post...

Thanks
 
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#8
make sure the spring in your lever isnt crooked and still mashing the button that makes your brake close,, are you sure you have the right pad for you bike?
 
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#9
The lever was completely off the bike, there was nothing pushing the plunger and it still dragged. The pads are stock, according to the previous owner.
 

jmics19067

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#10
this is a strange situation that sometimes happens. If someone fills the brake resorvoir while the pads are worn and then changes the brake pads with out letting out the extra fluid they can drag.
 

mhardee

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#11
Originally posted by jmics19067
this is a strange situation that sometimes happens. If someone fills the brake resorvoir while the pads are worn and then changes the brake pads with out letting out the extra fluid they can drag.
I have seen this on cars, so I guess it CAN happen on bikes as well... The inside of the brakeline breaks down and will not release the pressure in the line. It drove me nuts on my son's truck. New brake line and it's back to new.. It's a long shot, but....
 
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#12
The pads really don't retract much if any on their own, they are mainly pushed back by any wobble in the disc. In a good system, this isn't a very strong force, so if anything is dirty, it can drag as the pistons will not be pushed back.

On my roadrace bike I pull the brakes apart before every race weekend and clean everything thouroughly. With the speeds we generate, you can warp a disc in a hurry if the pistons don't fully retract. Plus, it's only 30 minutes of work, and probably drops my laptimes by .000137 seconds due to the extra speed. ;)
 
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#13
The pads really don't retract much if any on their own, they are mainly pushed back by any wobble in the disc. In a good system, this isn't a very strong force, so if anything is dirty, it can drag as the pistons will not be pushed back.

On my roadrace bike I pull the brakes apart before every race weekend and clean everything thouroughly. With the speeds we generate, you can warp a disc in a hurry if the pistons don't fully retract. Plus, it's only 30 minutes of work, and probably drops my laptimes by .000137 seconds due to the extra speed. ;)
That
The pads really don't retract much if any on their own, they are mainly pushed back by any wobble in the disc. In a good system, this isn't a very strong force, so if anything is dirty, it can drag as the pistons will not be pushed back.

On my roadrace bike I pull the brakes apart before every race weekend and clean everything thouroughly. With the speeds we generate, you can warp a disc in a hurry if the pistons don't fully retract. Plus, it's only 30 minutes of work, and probably drops my laptimes by .000137 seconds due to the extra speed. ;)
The pads really don't retract much if any on their own, they are mainly pushed back by any wobble in the disc. In a good system, this isn't a very strong force, so if anything is dirty, it can drag as the pistons will not be pushed back.

On my roadrace bike I pull the brakes apart before every race weekend and clean everything thouroughly. With the speeds we generate, you can warp a disc in a hurry if the pistons don't fully retract. Plus, it's only 30 minutes of work, and probably drops my laptimes by .000137 seconds due to the extra speed. ;)
That 0.000137s fully justifies the 30 minute investment. People would not believe what it costs to gain a full second. Squeezing lap times down is especially hard work on a tarmac tearer :)
 

Mully

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#14
18 year old post