Shitmano XT squish brake
Ok, so I posted this up before but here is the quick run down of the issue. I installed some prebled XT on my bike. They worked great! Loved them. Wondered why I stuck with BB7's for the time that I had them. Then I snagged the rear cable on the stupid handrail bringing it up from the basement (long story). Bottom line is that it caused a crack in the light up near the lever.????? What ever, I had already ordered new pieces so that I could trim them down anyway as they were a little long. I clipped the cable, installed the new end pieces and bled the system. It has never been the same! I got fed up with it after doing battle with it over the course of 2-3 days and took it to a local shop. The mechanic bled the thing for an hour while I stood there. It kicked his @ss as well. I opted to leave it the way it was as I had a race coming up. The brake worked though the first pull was 60% squish. Each successive squeeze of the lever results in greater pressure being required to squeeze the lever but the brakes don't generate any more power. So, I then found and picked up a stock Shimano replacement line. I looked up a how to on Ebay which is by far one of the best how to's I have seen as well as printed out the tech manual if you will directly from their site for how to change the line/bleed the system. Now, I don't have the shimano bleed kit so I simply did the over flow technique and strapped a large coffe can under the lever to catch all the excess fluid. Worked great, it all went in the can. Once there was no more air bubbles, I did it from the opposite end as directed, no bubbles, but the lever action still felt like crap and was slow to recoil once you let it go. I have been dealing with it since!
So, what do you think? I tell you I followed Shimano's directions to the T. Could their be something wrong with the lever? All my seals are in place and I have no fluid leaking anywhere out of the system. Like I said, it will work but no where near the way the front one does. I have since been to a couple of shops squeezing brake levers and every single one of them regardless of price/quality that has been a hydro set up has felt better than mine! WTH??
I figured I would run it by you guys to see if there have been any others with a similar experience out there. At this point, I have held off from taking it to a shop and leaving it as I would not have a bike to ride if I did. However, I am going out of town for a week on 10/9 and if I don't have it working right by then, it will simply get dropped off there while I am out of town. Hopefully some miracle will occur, the planets will line up and the powers that be will unite and BOOOM, a rear brake that works as good as the front!
Bleeding the brakes while they are still attached to the bike or removed? Front or rear? M775s?
I've experienced similar problems while bleeding Shimanos when I was trying to just do it quickly. And I've found that even though I thought that all air bubbles were gone from the lines, I would find more once I removed the brakes from the bike and bled them again. I also think that the M775 levers can be a little tricky and allow bubbles to somehow get trapped.
On the bike.
How do I bleed them off the bike? I mean, I understand that the lever/resevoir needs to be higher than the caliper but what are you hooking the lever to to keep it level if you will?
Bleed procedure not clear to me
I do the bottom up as well...Syringe full of fluid squeeze it into bleed nipple...watch bubbles come out of the reservior.
If cooked fluid, or bubbles come out keep going, I generally push about 100 ml through the reservior.
When the reservior is full, if the fluid is clean with no air, I just suck some out with the sryinge and keep going.
Takes about 15 mins and all is good.
Be sure you keep the reservior port submerged in fluid...
I just put the bike on the stand...postion the reservior so it is horizontal...
If it's the rear, try leaving the lever attached at the bar, and detach the caliper and allow it to hang to try to get as straight a brake line as possible. I've done this successfully several times by tilting the bike up in a repair stand. Tap the caliper and lever to try to free up all the bubbles. I usually only need to do a standard top-down bleed.
I have bled top down and basically made sure there was always fluid in the res and also pushed fluid from bottom up.
Maybe I will give this one more shot from the bottom up again. It does suck without the stupid bleed kit though. I really think I might have to take the plunge and buy one. It just amazes me how much that stupid thing costs for what it is. It would certainly save me from having to constantly stop pushing so I could suck fluid out of the res or having to clean the whole bar area due to the overflow technique described above in my first post.
I tell ya, I have thought about completely draining the whole thing as well and just starting as if the line was empty.
Originally Posted by 1SPD
If the price is bugging you just get two big syringes from the drug store and a foot or so of tubing that fits over the bleed nipple....
Still need the fluid of course.
For a bleed kit (for the top down bleed), all you should need is new fluid, a catch bottle and hose/tubing. Do you have the yellow "block" to go between the pistons once the pads are removed?
Another tip that I read years ago and use now, is to find a split compression olive (I think maybe Jagwire makes them) from your LBS. And use this slid over the length of tubing where it is attached to the bleed nipple at the caliper. It will really help in keeping the hose in place.
And I use an old Shimano mineral oil bottle with the center inner cap/seal drilled to match the diameter of the bleed hose. Makes for a tight fit and very little mess.
my guess would be that there is air in the lever. I found that if i rapidly pulled and released the lever (bleed screw CLOSED) that tiny bubbles would flow out of the lever. I did it for about 3-4 minutes until bubbles stopped flowing. BAM, perfect lever feel. I also heard of people that rubber band their levers open over night to get bubbles to float out. give either of those two methods a shot?
EDIT... btw, what fluid did you use. the slow rebound sounds like either a. the return spring isn't right on the pads or b. you used far too viscous of mineral oil.
Odd, I posted up last night after taking yet another butt woopin on this but the post is not here. hmmmm.
In any case, I will admit that I used off the shelf mineral oil from CVS but will add that the shop that tried bleeding them for an hour the last time was using Shimano mineral oil and had the same sort of luck.
So, I started from the bottom up last night and flushed about 40cc's through them. No bubbles were vissible at the 10cc point but I kept going. I tapped the caliper, the hose, and the lever during the process. I over flowed it and then stuck the seal and cap back on. First pull was squish. Second pull had more pressure, Third pull was pretty hard. let it sit for 15 seconds and the first pull again was squish. I'm done! The bike will simply be going to a different shop i n my area that I know has more experience in dealing with shimano brakes (hydraulic brakes that is). I'm am sure I am probably over looking something simple here but I just can't take it any more.
I have the same problem as you, prebled XT (from ebay, seller was september_19 IIRC), rear brake has been annoying me for the past 6 months or so with that squish feeling. I get plenty of power after the second pull on the lever though. I had a pro mechanic bleed them last month, made no difference. I've never been successful in bleeding a brake so I haven't even tried.
Now I'm thinking we may both have a lemon on our hands :/
Well, that very well may be the case. But both my brakes worked like a charm when I got them. Once I cracked the cable on the rear one, it has never been the same. Perhaps this is why they sell them prebled. They must know some trick that they are not telling anyone or it is a one time deal and once maintenance is needed you can kiss them goodbye.
Originally Posted by 1SPD
1spd... did you try purging bubbles from the lever? If there is air built up in the lever it will feel just as you describe. With the servo wave it tends to pressurize/pump up even if there is air in the system. Also, medical mineral oil is not going to work for you, you will need to get some proper mineral oil to get correct lever feel/actuation.
btw, where are you located, if your in the SF bay area, I'll put my money where my mouth is and help you get them set up properly.
Last edited by markj2k4; 09-22-2010 at 08:34 AM.
Ok, I have given up as I stated before. I am not going to tinker with them any more and will simply take it to the shop in another two weeks.
I also went ahead and picked up a complete set of Avid BB7's on ebay last night. They are used but are complete with new pads, rotors, levers, and Gore cables. I had BB7's before I got the XT's and plan on just sticking them back on. I will then put the XT's on my other SS bike that I am working on building up. It is sort of being built with all my older/cheaper stock parts that came with the one that I have so it will be nice to have decent brakes on it (even if they still work as they do now, they are better than the stock Aquila's that came with it).
I did ride the bike last night and it was no different than normal. They work well enough to ride but the rear just isn't as good as it could be. Oh well.
For next time....
Try removing the calipers and rotating them while tapping it may be that so air is stuck in there somewhere.
1SPD, did you push the pistons back as far as they will go into the calipers and keep something in between the pads to hold them in? If not you'll never get all of the air out.
If you did then air must be in the lever piston bore and as others have said you'll have to pump the lever a few times while you bleed, also roll the membrane on when you replace it to ensure that it has no trapped air under it.
I had the block in there but I can say that the pistons move ever so slightly. Perhaps that is part of it. But since it is the only block I have there isn't much else that I can do at the moment. I may try to play around with it this weekend. But will make sure I have some beer or something stronger on hand before I get started. I was definitely unprepared the last go around!
Oh NO NO NO! That's the wrong oil to use! Use Shimano oil or the Pentosin CHF 7.1.
Originally Posted by 1SPD
BTW, I bleed by detaching the caliper and having it higher than the brake lever. That gives bubbles a chance to float UP. I also occasionally tap the line and caliper and turn the caliper in different orientations.
It also helps to push the fluid thru rapidly in order to dislodge bubbles.
One other trick I have used is to have the bleed valve fully open, and quickly actuate the lever back and forth between the partially pulled and fully pulled position. That causes fluid to slosh back and forth and also helps dislodge bubbles. Don't return the lever to the unpulled position, or you will suck oil out of the master cylinder.
When I replaced my hoses, I thought things were good, but after about 2 months, the rear wouldn't work at all. What had happened is that the hose was kinked just at the compression fitting, such that it was affecting things and apparently letting air into the system. The shop cut the hose just after the fitting, replaced the fitting, and rebled- voila, works great!
Originally Posted by jeffscott
.... Make sure the reservoir is the highest thing in the system.
On my geared bike I put a Titec H-Bar on there with some odd hose routing. A bit of the hose actually stuck up slightly higher than the lever. This made for some weird bleeding issues. Whatever tiny amount of air left in the reservoir would somehow migrate into the hose and ended up in the line. The fix for me was to shorten the hose so it didn't stick up, and to try and chase all of the air out of the system I could. I would set the pistons with the goofy yellow block thing and fill the reservoir to the brim, then add the bladder membrane and cover, spilling some fluid out the top before snugging the cap down. I also sometimes angle the bike so the lever points slightly up, forcing air out that way. Pump pump pump bubble bubble. Make sure you don't fill the reservoir up with the pistons all the way in (open) or when they move out, it might run the reservoir dry. Set it with the yellow plastic pad block thing.
I've bled the systems from the top down, or bottom up. Both seem to work for me. I do them like car brakes. Pump it up to work the bubbles loose, then squirt them out either the bottom or the top. The only bleed issues I ever had with Shimano was because of my weird hose issue the one time.
You can also try removing the pads and pumping the pistons out and closer together (but carefully not all the way together) and then push them all the way back in. Sometimes that will push some air out of the line.
Yeah, and second sticking to Shimano brake fluid. Funny, I didn't know about the Pentosin CHF 7.1 being okay to use. I have a liter of that stuff I picked up for my Audi's power steering sitting in my garage unopened. I mean, every lever or brake caliper I ever bought from Shimano seems to include 2 or 3 small bottles of their brake fluid. I still have like 3 unopened bottles... so it hasn't really been and issue for me.
Yeah, you can get that stuff from CVS for $3 or whatever, but you can get a liter of the Shimano stuff for $28, which is a may times over lifetime supply. You might save a few bucks, but if you have brake issues, you will never know if its the fluid or not. I mean, you really aren't going to miss $25 in your life, but you will miss all that time of potentially dealing with issues, and possible ruined bike rides. I'm sure you can get the automotive stuff at any Kragen/Checker kinda place (if that really is okay to use). Every Audi and VW since 1993 at least uses that stuff for PS fluid.
OP: you sure your new replacement hose is good? It doesn't have a tiny crack or something to get tiny air bubbles in or something? Air molecules are way smaller than brake fluid molecules.
Last edited by pimpbot; 09-23-2010 at 04:37 PM.
Just a quick update to my brakes.
I manned up and decided to clean my brakes, discovered that the front had major piston dominance (so that one piston was moving much more than the other) and the rear had one stuck piston. Cleaned the front brake pistons, pushed pistons in and it was perfect after that. Maybe it needs a bleed sometime in the future but it feels great now.
Bled the rear brake since I accidentally removed one piston and some air got in. I cleaned both pistons, pushed them in, unstuck the piston and my rear is pretty much 100% now. Oh and my pad was 80-90% worn down so I put a new one in there, the worn pad may have exaggerated the stuck piston effect.
Pretty simple procedure, I used bleed instructions that i found on the nsmb boards. My brakes have had a lot of use in the 18 months since I got them, so it's not surprising that they needed a quick overhaul.
Yep, I am done dealing with them myself! I switched back to BB7's and am quite happy with their performance at this point. The simplicity is there as well.
Glad you were able to get yours to work.