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post #1 of Old 10-01-2006, 03:05 PM Thread Starter
cookiemonster
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why are my front brakes so stiff - 600R

My front brake lever is way too stiff, even on the highest number setting. I just flushed the front brakes. Currently have stock lines, pads and dot 4. The highest setting is just slightly less stiff than the lowest on the brake lever dial. Basically a little squeeze feels like slamming with full force. The bike is a 96 yzf600
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post #2 of Old 10-01-2006, 03:54 PM
rb4123
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Did you overfill the resirvoir? Check the master cylinder too for foreign objects in the valving.
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post #3 of Old 10-02-2006, 08:38 AM
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there is no "setting" on the brakes.. all that does is change how far the lever is from the bar.


sounds like you need to do some maintenance it... what have you done so far?
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post #4 of Old 10-02-2006, 11:40 PM
stive403
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is there drag on the brakes when you don't have the brakes applied at all? Like if you put the bike on the front stand and spin the wheel, does it spin freely?
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post #5 of Old 10-05-2006, 11:01 PM Thread Starter
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Yes there is drag on the front wheel, and the only maintenance was the bleeding.
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post #6 of Old 10-06-2006, 02:13 AM
silverr6
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Make sure you are squeezing them with only two fingers, and do it gently. It sounds to me like you might be just a bit inexperienced, which is fine but new riders need to understand motorcycle brakes are waaaay different from car brakes.
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post #7 of Old 10-06-2006, 11:58 AM Thread Starter
cookiemonster
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^I know how to work the brakes

If there is serious drag on the front tire does that mean the piston seals need replacement or something is wrong inside the master cyclinder?
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post #8 of Old 10-06-2006, 02:22 PM
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Possibly, if there's a lot of drag, that means the pistons aren't pulling back at all (retracting) and you would have instant lever. It still shouldn't seam any more powerful, but you would have pressure right away, which isn't what you really want and will put extra heat into your system as you are dragging the brakes at all times. You should be getting a few rotations out of your front wheel when on a stand.

and as said before, the dial on the lever won't change how stiff the brakes are, but will adjust the reach.

You say the brakes are too stiff... or too powerful? The only things that will effect how stiff the brakes feel are: Caliper retraction, caliper deflection, brake line expansion, fluid compression, seal compliance. The things that will effect brake power are: Master cylinder piston diameter, caliper piston diameter (and of course number of pistons at that point), master cylinder lever reach, friction material (pads).

So seeing as all you did was flush fluid, I'm thinking maybe your old fluid might have been junk and had water/air in it and now your brakes likely feel the way they should... Always hard to diagnose when you don't have the bike in front of you.

If there is drag on the front wheel, try taking the calipers off, push the pistons back into the calipers (be careful brake fluid doesn't overflow the reservoir while doing this), remount the calipers, and pump the lever to push the pistons back out, try rotating the wheel again.
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post #9 of Old 10-06-2006, 03:39 PM Thread Starter
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ok let me go into more detail

When I squeeze the lever with just a little bit of pressure it has the same effect as doing a panic stop, almost to a point of locking up the front tire.

If I gently squeeze the front brake lever at speeds the front end begins to heavily vibrate.

The setting of 1-4 on the brake lever dial has little effect, basically brake lever is always the farthest distance from bar on any setting.

When the front tire is off the ground it will maybe do 1/2 a full spin, even when rolling the bike I can hear the pads pressured on the rotors with no pressure on the brake lever.
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post #10 of Old 10-07-2006, 10:13 AM
fjman
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You will normally hear the pads on the rotor. Not always, but this is really very common.

However, being only able to rotate the tire one turn while on a stand? Your shit is dragging hard, mate. Odds are that the seals on the caliper pistons are 1) shot or 2) full of crap.

Hate to say it, but bite the bullet and rebuild the calipers. You may not need to replace the pistons if you just get them nice and smooth (never sand up and down them, always around), replace the seals, clean the crap out of the housing(s). When you put it back together, use nice fresh brake fluid to lubricate the pistons as you put them in. Rebleed the system and try again.

You also may want to try a different set of pads, as a cheap experiment, while you're in there.

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