Front brake help?

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4/13/2018 6:29 PM

So I thought I was finally going to take my freshly built 06 RM 250 to the track but ran into a problem. The front brakes seem to be sticking and the rotor gets really hot just putting around the yard. The brake setup is a CRF master cylinder with Galfer steel line and 270mm rotor. The caliper bracket is sliding free on the pins. I am assuming I need a rebuild kit for the caliper. I took the caliper off and the brake pad out and pulled the brake lever. One piston comes out much farther/faster than the other so I took the caliper apart but the only thing I found was a little dirt in one of the seals(on the sticking piston). So I clean it up and put it back together but still not any better. Any ideas other than replacing the pistons and seals? Thanks!

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4/14/2018 6:36 AM

When i run into this, what i do is tear down the master cylinder and caliper & take it to get vapor blasted or clean it up the best you can if thats not available to you. Rebuild both.

Not sure how “over the top” my process is, but its the easiest way for me to solve brake problems. I dont like trying to chase down issues in the caliper or master cylinder. Re-do it all and be done. Its not expensive by any means.

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4/14/2018 6:58 AM

Too much fluid in the master will also cause this.

Paw Paw

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4/14/2018 7:18 AM

kb228 wrote:

When i run into this, what i do is tear down the master cylinder and caliper & take it to get vapor blasted or clean it up ...more

Master cylinder is new. I will rebuild the caliper. Thanks!

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4/14/2018 7:22 AM

Paw Paw 271 wrote:

Too much fluid in the master will also cause this.

Paw Paw

The level in the cylinder was pretty high but during bleeding of course we let it get down some but it didn't help. I guess I will just rebuild the caliper and fill with correct fluid level. One of the seals had a small tear in it. Idk if this would cause the piston to stick though. Thank you for your reply.

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4/19/2018 11:40 PM

I am having a similar problem with my front brake.
I got hit by a stone off the rider in front of me which left my index finger throbbing and at the same time I lost the front brake with the lever travelling all the way back to the bars.

It definitely reacted like a bent disc, although I have experienced a damaged seal in the master cylinder after a collision previously, and considering it was linked to the hit to hand this was my first assumption. Anyway, on inspection at the track the disc did have a bend to it, so I ordered a new disc and seal kit for the master cylinder just to cover both bases.

I fit both parts last night and this whole thing has me scratching my head, bled the system through but couldn't get a good feel at the lever. When operating it's as if the caliper isn't sat straight as you can see the disc flexing from the bottom.

If I remove the wheel I can get a great feel at the lever, which suggests to me that the problem is either with the new disc or the caliper mounting.

I can improve things by shimming the caliper at the top mounting bolt, but I shouldn't need to do that and the feel at the lever is still not as good as should be.

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4/20/2018 1:22 AM

Mucktub wrote:

I am having a similar problem with my front brake.
I got hit by a stone off the rider in front of me which left my index ...more

Sorry if its a dumb question but did you put new pads on and grease the slide pins when you did the rotor?

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4/20/2018 2:20 AM

It's not a dumb question kb228 I appreciate any feedback whatsoever , but yes I've done all that.

It seems to me that the problem is somehow with the mounting of caliper and it is running at a slight angle. Quite how this can happen by being smashed with a stone at the master cylinder end I don't know. I'm not a big believer in coincidence.

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4/20/2018 2:26 AM

Id take a guess and say you hit something and bent your bracket and rotor. Its hard to say without lookig at it. Can you remove your bracket and check it on a flat table for bending?

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4/20/2018 2:27 AM

When my YZ starter having a front brake hanging up, it turned out to be the brake line. It had either gone bad from age, or a crash. Would allow fliud the to flow under pressure. But would not let it return.

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4/20/2018 2:49 AM

That's potentially not a bad shout truckdriver. The bike in question is a 2016 RMZ450, I also have an 08 RM250 which lives at work at the moment, I'm taking it home tonight and I will see if the master cylinder, line and caliper will swap over. Start your suzuki jokes now.

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4/20/2018 2:56 AM

Mucktub wrote:

That's potentially not a bad shout truckdriver. The bike in question is a 2016 RMZ450, I also have an 08 RM250 which lives at ...more

Its called a slowzuki

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4/20/2018 3:02 AM

cool Not at the moment, no front brake means I get to work on my corner speed.
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4/20/2018 1:54 PM

Just got done working on the bike. New pistons and seals fixed the problem. Thanks for the replies!

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