| Author | Message | ||
     Thefleshrocket |
I've seen other people on the forum complain about the brake lever requiring "too much" movement before the brake starts to engage. My 1125R did this as well. I bled the brake with a vacuum hand pump (which usually works great) but it didn't help at all. I also tried the "zip tie the lever to the clip-on overnight" several times. The lever would feel better for a few stops but then revert to its spongy feel. Last week I removed the front caliper and wheel to change out the tire. When reinstalling the wheel, I pushed the brake pads (and therefore the caliper pistons) somewhat back into the caliper so that the caliper would fit over the rotor more easily. After doing so, the brake lever has been noticeably firmer. It's not quite as firm as the lever on my '03 GSX-R1000 (the brake on that bike engages so quickly that it would actually slow the bike down before the brake light switch was tripped--I had to grind down the switch actuator on the lever to fix that) but it is a very noticeable improvement nonetheless. I suspect that there was some air trapped in the caliper itself and that pushing the pistons back into the caliper forced that air back up into the line and eventually out the master cylinder reservoir. So if your 1125 is plagued with a spongy lever or one that takes too much travel to start engaging the brake, try this trick and see if it helps. | ||
| Ratbuell |
When you do the zip-tie-to-grip trick, you do have the master cylinder cover loose, right? You have to break that seal in order for the air to bubble out of the fluid. | ||
| Ysracer |
That's not the cause. The piston to seal interface has a bit of stiction. As the brake pads wear a bit, a gap develops between pad and rotor due to the caliper pistons not sliding thru the seals. There isn't enough movement and the rubber seals pull the pistons back to their original location. When you push the pistons in and then pump them back out you are creating a new neutral point. The excess lever travel will reappear in a few hundred miles to confirm this...... On bikes with single acting calipers it's easy to just push the caliper over while mounted on the bike, pump the lever and go again. New sport bikes require a bit more effort. | ||
| _gdkp_ |
@ysracer sorry my englisch is not the best, could you describe the last statement - or give us a manual how to adjust that? Thank you! | ||
| Thefleshrocket |
Ratbuell, no I do not have the master cylinder cover off. Why would that be necessary for the ziptie trick to work? The ziptie trick just opens the master cylinder up so any air in the line or caliper can float up into the reservoir. The quantity of air and fluid in the system are not changing, just the location of any potential air bubbles in the system. Ysracer, I don't think this issue is due to piston to seal stiction. I noticed this problem from day one when my 1125 had 27 miles on it, and it has not changed at all in approximately 2400 miles, suggesting that pad wear doesn't have a bearing on it. I've logged about 150 miles on the bike since changing the front tire and the issue has not returned. I'll post back in a few hundred miles, but I don't have any reason to think that it will come back. | ||
| _gdkp_ |
@thefleshrocket on my thread "brake-point not the best", you have written a link, but itīs not functionable - please be so kind and update. Thanks! | ||
| Albert666 |
i just had some new tyres fitted when i put everything back together the lever had much better feel thats all i did | ||
| Twintalon |
YSracer: So is there any special lubrication that can be applied to minimize the stiction? I don't what WHAT the problem is, but i'm not a fan of the spongy brake lever, and have been considering options to help firm it up. I've basically reached the point where i'm willing to put a different master cylinder on the bike. With the correct master cylinder swap, I have to believe power and feel at the lever would be light years better than stock. (Message edited by twintalon on July 21, 2010) | ||
| Thefleshrocket |
gdkp, I removed put the bike up on stands and removed the front wheel and the front brake caliper. With the front brake caliper off, I was able to use a screwdriver to gently (to avoid damaging the pads' friction material) push the brake pads back into the caliper. I then reinstalled the caliper and wheel. That was all it took to get the brake lever having far less slack space. | ||
| Thefleshrocket |
gdkp, my link in your "brake point not the best" is actually to this thread. | ||
| Ysracer |
It occurs on every bike, it's just more noticeable on this one because of the small master cylinder piston diameter (small change at caliper = big difference at lever). I use a Brembo 19 RCS master cylinder on mine and it's less of a issue. Then again, I have the wheel off about every 150 miles for tire and brake pad replacement since it's a track bike. (Message edited by ysracer on July 21, 2010) | ||
| _gdkp_ |
@theflesh but i have to open my master cylinder and will suck out a little brake fluid right? so if i going to press the brake pads in the caliper, my fluid will get on top... so i will buy ebc pads and remove the caliper, open the master cylinder, suck out little fluid, press in the brake pads, change them, but back the caliper to my rotor, and pump the brake lever... is this the right order? Thanks! | ||
| Thefleshrocket |
gdkp, have you ever added any brake fluid to your front brake reservoir? If not then you don't have to worry about draining any out when you compress the pistons back into the caliper. When your bike was new, the pads were the same thickness as the replacement pads you plan to install, so even if you push the pistons back in all of the way, the brake fluid will stay below the top of the reservoir. However, if you have added fluid at some point, you may want to suck some out of the reservoir to prevent it from overflowing. Your steps are correct except that you will have to remove the front wheel in order to get the brake caliper off. Also, I personally think there are better pad choices than (any kind of) EBC but I won't go into that here. | ||
| _gdkp_ |
So i have an 08 Modell and my bike was standing for til 2 years, i bought it this year with 0 miles on it! So for my own security, my Dealer changed the brake fluid .... i live in austria, so for me its the easiest way to buy ebc pads... so on why i have to remove my wheel? Normally i mount the caliper off... orgen id it Not possible on buell bikes? | ||
| Thefleshrocket |
The caliper on the 1125s is wedged between the fork and the wheel, and it's BIG. I don't think there is any way to remove the caliper without removing the wheel. When I removed the front wheel, it took a bit of wiggling to get the caliper off even though I'd already taken the front axle out and could move the wheel around. | ||
| Ratbuell |
Flesh - the reason I pop the lid on the m/c is so the pressure is released. Pressure keeps the air trapped in the liquid. Coolant systems don't boil because they have pressure, that keeps the oxygen imprisoned in the liquid. Release the pressure, and you get boiling (oxygen being released from the liquid). Granted we're not talking boiling here...but the theory sounds valid. Pressurized liquid is "harder" than air, so the liquid in the line will "hold" the air down if you have pressure in the system. Beyond all that...well, with the lid popped loose (but still in place to keep dirt out), it works for me every single time. Loosen lid first, then squeeze the lever slowly so you open the valve without splashing fluid everywhere, zip tie in place, and leave for the night. In the morning, remove the lid, cut the zip tie so the lever returns to normal position, top off fluid as needed, and button the lid back up. Presto - new brakes again. | ||
| 1125rcya |
Whats the chances it could be a spring or a piston inside the clutch lever? They make rebuild kits. Its a shot in the dark but worth looking at? | ||
| Dannybuell |
This sounds all too familiar on something my 95Kmi S1 (original caliper) likes to have done to it. pushing those pistons back always seems to bring the response level up. You guys just explained why my CR may be so spongy. | ||
| 1125rcya |
This is a video for a back break master cylinder, but its the same concept as the front. http://www.youtube.com/watch?v=o1KlBme_ye8 Happy hunting  | ||
| _gdkp_ |
hi guys, so on today i will try the zip-tie trick, so i just pull with 3 fingers on my brake lever (open lid @ m/c). Now if i look trough the fluid into the m/c i see a little slot/port, then i pull the lever slowly - i see for short time that the port is closed (very low brake feeling), then i pull the lever more nearly to the throttle-grips the slot/port is open, so if i press agressiv on the lever (unusual hard) - i also get the slot/port open. If i understand, that if i press the lever stronger everytime, more fluid is pressed into the brake lines right? So should i press the lever if i see the open slot/port - for doing the zip-tie trick? Thanks a lot! | ||
| Thefleshrocket |
gdkp, when I do the ziptie trick, I pull the lever back so it's about 3/4" to 1" from the grip. I've never looked into the reservoir to see where the piston was in its travel. | ||
| _gdkp_ |
@fleshrocket So itīs really tight you pull the lever right? Cause 1" is really near (very hard braking level) at the grip (i think...). | ||
| Nukeblue |
mine always feel much better after collapsing. but it usually gets spongy again pretty quick | ||
| _gdkp_ |
@nukeblue so i tested it over 10 hours, and at the beginning after the zip-tie procedure the brake was really nice, so i drive 3 kmīs and this "spongy" or not so hard is coming back very fast  ... | ||
| Reepicheep |
Just to elaborate on a few things here... When the brake lever is all the way out, air coming up from the calipers and lines can bubble up right out of the master cylinder and up though the fluid. When you start to push the lever, the piston closes that bleed hole, and air can no longer come out. So, for example, if you put a straw and blew into the opened bleeder valve, air would bubble up out the master cylinder if the lever wasn't pushed. As soon as you pull the lever, the piston in there blocks that path, and you couldn't blow air through anymore. So if you have air in the system, and it can keep moving up, it will self bleed to some degree. I think the "zip tie" trick (I use a big velcro strap) works because the bubbles that are in the system will shrink dramatically under pressure. Open a new 2 litre of sprite and watch the bubbles form and expand when you release the pressure... they go from invisibly small to 1/4 inch big. Squeezing that lever, and leaving it squeezed, does the opposite. So it takes any 1/4" sized bubble and reduces it to some micro bubble. That micro bubble might be dislodged in the process, and work its way up to the master cylinder. Or it might get small enough that it can make its way through some narrow passage that it "stuck in" before. Then you release the lever, and the bubble goes right back to it's 1/4 inch size, but hopefully it is higher in the system, and eventually right at the master cylinder, and it just pops right out. For that reason, when I release the lever after an over night squeeze, I let it slam open, hoping to dislodge bubbles (they are expanding and being whacked at the same time). It won't work if there is a perfect little bubble trap in the caliper somewhere, but I'm guessing brake designers work pretty hard to avoid those. (Though my old Yamaha Radian had one half way up). | ||
| S21125r |
Question... what is the theory behind the zip tie trick? My understanding is the bleed hole in the master cylinder piston is only exposed to the res when the brake lever is not engaged (to vent excess presure/fluid as the fluid heat and expands.) When the brake is engaged the bleed hole is covered so that proper lever pressure can build. One thought on the original post though... possible that one of the pistons has some crud (or nick) between it and the seal. There are 8 of em so you may have look closely. Pushing the pistons back may temporarily fix it as the crud/nick will be in a different spot relative to the seal but could return once the piston return to their original location. Had the opposite of this happen on my old s2 - brakes worked fine but the area of the pistons "exposed" were corroded. When I did a pad change, those corrodes surfaces were now interfacing with the seals... not so good. Good luck, but if several bleed sessions aren't doing it then you may need to rebuild the caliper and or master cylinder. | ||
| S21125r |
Sorry reep - didn't see your post... | ||
| Nukeblue |
really nothing to worry about. i used to race with the spongy lever all the time  they never failed | ||
| Thefleshrocket |
S21125R, the spongy lever problem has existed since I got my 1125 with 27 miles on it and it hasn't changed over the 2500 or so miles I've put on it thus far. Your idea could certainly be possible if this was something that had crept up on a bike with a few more miles, though. gdkp, try removing the caliper and pushing the pistons back in--I am confident it will help, maybe permanently. | ||
| _gdkp_ |
i will do if my ebc pads arrived, cause i think these are really crappy OEM pads ... i like rough braking, and dont need too much feel... So on is there any possibility to change the pads without removing the front wheel? - Cause i donīt want to buy a front stand/holder, just for that "normally little" thing, and our dealers / motorcycle companies want to have more than 70$ for changing brake pads *HUH* |
