Hello, guys!

My problem is that the brake lever stiffens when I squeeze it slowly, like if I'm driving. When I pull it fast and use more force there is no problem but when I do it slowly and carefully, as if I was stopping on the road, it stiffens and what happens in real life is: When I'm riding and I need to break, I pull the lever slowly and it stops at a point(the stiffening), when I push harder it suddenly works as it should and I get a stopped front tire while doing 60 mph which is close to falling.... I recently changed the brake fluid because the old fluid was very very bad and it couldn't stop properly. After the fluid change the bike stops a lot better.

Also, when I push the lever down or I pull it up and then squeeze it, there is no problem at all...

After the fluid change I let the air out as I should have, I even did that process like a hundred times but still no change... I unbolted the lever, cleaned it with WD and greased it - again nothing...

Please help, guys, I'm out of options...

Here's a video of me showing you what I'm struggling with...

Are you sure you didn't overtighten the bolt that holds the lever in the perch?

Yes, I'm sure. I even did it without the bolt being tightened at all and there was no change.

Squirt some WD-40 in the slot where it pivots.  They get sticky now and then.

If it were me, I'd start from the top and work my way down. Check the lever itself for any build-up. Clean it and lubricate it. Check the master cylinder for gunk. Then make sure the line is nice and clean... no build-up, no mess, no air. If the old fluid was really that bad, you could have some dried up fluid still in there causing problems. Next option would be to check the caliper. If the pistons are having issues moving in and out, that could be your problem. One random tip I heard years back was to tie your lever fully back over night. Pull it all the way in, use wire or bungee cord, or anything to hold it in position. Not sure exactly why, but I've heard it helps.

gsJack, I squirted WD, I actually bathed the MF in it but nothing happened...

Supa, the lever has been cleaned thoroughly and then lubricated but no help... the master cylinder is clean, I circulated the whole system with brand new fluid, 500 ml went through that line... still nothing... the caliper is OK, I think. I squeeze the brake a couple of times and then release it and the tyre spins freely. I guess next thing should be that lever tie over night.

Did you disassemble your MC and clean/inspect it?  It almost sounds like there is a problem with the MC piston moving through its travel. 

You need some snap ring pliers with a very skinny point to get the snap ring that holds the piston into the MC out.  I had to file the end of mine down a little, and then they worked like a charm.

I just tied the lever all the way just like Supa said.

bombsquad83, I haven't inspected the pistons yet, I haven't even detached the caliper from the disc. I think I messed up somewhere because that occured after the fluid change but still I can't imagine what could've happen...? Or maybe it is indeed a piston problem and I haven't had it so far because the old fluid was way too old and I couldn't use all the brake force? I don't know... I will inspect the piston tomorrow.

By the way, the sound you hear in the video comes from the upper part, the lever/fluid bowl.

I was talking about the piston and seal in the master cylinder, not the caliper.

Quote from: bombsquad83 on November 13, 2014, 07:49:38 PM
I was talking about the piston and seal in the master cylinder, not the caliper.

I'm with Bomb on this one. If you've cleaned / greased the pivot bolt and you're still getting a sticky lever, the next possibility I'd look at is either a M/C rebuild kit or an entire new M/C. Sometimes it is actually the body of the master cylinder that causes the piston to stick.

Fwiw, Suzuki used the same piston on plenty of bikes, so the rebuild kits are pretty easy to find.

A friend of mine has a 07' GSR and when I pulled his lever it was the same as mine, not as much but still the same problem... I don't think that's normal in any way but it's interesting that when I pull or push the lever up or down and then squeeze it - it goes smoothly all the way...

PS: I will now remove the lever and lubricate it again and if that doesn't fix it I'll take the master cylinder off and clean it thoroughly, might aswell take the caliper off and clean the piston.

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Based on your description and the fact that pushing or pulling the lever up/down and it works fine leads me to believe the issue is either in your lever or your master cylinder. I would disassemble the master cylinder assembly, clean it entirely (paying extra attention to the piston), and reassemble it making sure that everything is seated properly. This diagram might help you figure out where the issue could be.




Edit: added image...

It's smoother if you push the lever up or down? I'd guess it definitely has something to do with the brake lever pivot bolt. Clean / grease / replace.

Watched the vid... that is Exactly what my lever did when I got the bike.  I had changed the fluid and still had the problem (needed to do that anyway).  I could pull the lever in and out quickly while stopped and it wouldn't show a problem... slow it down like you are actually using the front brake correctly and it would stick at points along the slow pull... that problem out on the road, applying the lever slowly it would kind of catch a little and get harder to pull for a micro second, then I would add more tension to overcome it, and it would force me to jerk past the sticky point and really catch the brakes - very scary as a newer rider.  Looked just like your lever in the vid.  I had read a post from gsJack about the lever kind of sticking at times, and his solution of applying WD40 every so often to it.  I went ahead and tried it, it took a few application and working it in the right areas, but that is ultimately what it was.  Since then, I've done this process at the beginning of each season, and it hasn't occurred since.

- Bboy

Well, I started cleaning my chain today and cut my finger badly.... I just got operated and will be sitting in hospital for 2-3 days, never having nail anymore im so stupid.....

That being done I will not be Able to work on my bike for a while but as soon as i get better i will continue and update you on my case...


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Ouch DD.  Feel better and recover swiftly!

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Thank you!


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Bummer DD hope you recover well. The brake problem sounds like 'sticktion' somewhere in the system. My first step would have to be a complete disassembly and rebuild of the brake system. This might sound like a hassle, but if you've done it once or twice, it's a kitty cat of a job.

I could be that your flexible brake hose has collapsed internally and is acting like a check valve. See if the brake is dragging after stopping.

regards
mech