Brake issue: common or uncommon?

[J.Moto]

Last weekend I installed new lines, pads and fluids for the front end brakes. I bled the system out and everything was real firm and solid. 3 days later the firmness may have decreased just a tad.

Yesterday on the way home, I had to use the brakes fairly vigorously (~120mph - 0 mph). After that run, the brakes got really soft, as in I pulled the lever in all the way and received no response. After a couple more pumps there was some response, but then I noticed a chatter in the front end at low speed. After speeding up, the chatter disappeared and with a few more pumps the brakes response was mostly there and mostly firm.

This morning when I jumped on the bike to head to work and got that chatter right away and no brake response. After some pumping of the lever they firmed up, the chatter dissapeared and the response was mostly there.

My guess is there is still air in the lines and the chatter resulted from not enough pressure behind the pads which allowed them rattle around between the caliper and rotor. But how common is this? The brakes were really solid when done so I don't see them softening up so much. I didn't see any fluid leaking.

[ADRATH]

I'm hoping to get braided lines my next paycheque. I would try and change the fluid and purge the system again.

[harbiho]

When you bled the system, did you start with the master..........then the calipers?

[curley]

a) fail to top off the master cylinder's reservoir ?- so after the pads bed in - the level of the master cylinder's reservoir drops far enough to get air in the system and you have to start all over again.
b) Leaky master cylinder ( soft lever)
c) banjo bolt "gaskets" ( washers) worn out or dirty
d) Ooops left the bleeders loose

[J.Moto]

The brakes were bled only through the calipers. How would you bleed from the master cylinder?

Curley:
A) I'm pretty sure that didn't happen
B) Hmmm, prolly not. How do you test?
C) Brand new parts
D) I don't think that happened either...didn't see anything leaking.

[agirls]

I would have guessed A, but you say that is not so. It's gotta be air bubbles. I did the same stuff (lines, pads, etc.) the day before a trackday (probably not very smart since I'm a new) and had no problems. I did do A though (by myself), and went damn it, and started over. PIA. Oh no, never mind. I thought A was failed to refill the reservoir while you were bleeding the brakes before the level was low enough to allow air in. That is what I did. I realized the level was pretty damn low when I stopped bleeding to refill the master cylinder and thought to be safe, I'm gonna start over (bleeding). Did you bleed the brakes by yourself, or did someone keep the reservoir full while you bleed the brakes?

[curley]

b) testing master cylinder -
back in the old days ( before Banjo bolts) - we had flare nuts and some soft copper tubing - you make a "brake line" that goes from the output of the master cylinder and back into the reservoir (a "loop"from the output to the input" ) but the end of the line ( going into the reservoir) was below the brake fluid level and visible - If after pumping the lever several times you continued to see air bubbles coming out of the line - you had a leaky master cylinder - air was somehow getting in the circuit - this is also the fastest way I know how to "bleed" a new master cylinder. If you have replaced your old rubber band lines with nice new stainless steel braided lines - use a short rubber brake hose and try the above procedure - or cut up a long one and save it in your tool box for the next time

another tip - but you have to be careful - take the bleeders all the way out and wrap the threaded area with teflon tape - be careful NOT to get tape on the bullet nose where the bleed hole is - just on the threads - thread it back into the brake caliper - as you bleed the brakes - the tape will keep air from "sneaking" back in before you get a chance to tighten the bleeder.
Concerned about Teflon and brake fluid? - well most hi performance brake lines are Teflon hose with a stainless steel overbraid - the braid works like a Chinese handcuff - not letting the hose grow.
good luck!

[MotoDave]

most liekly you have air trapped right at the end of the master cylinder, by the banjo bolt. Either get a banjo with a bleeder in it, or just crack the banjo bolt a tiny bit (will get messy). Or you can have a friend help you lean the bike over on its side until the reservoir is above the outlet of the mc, and just work the lever for a bit. Air will usually bleed itself out this way.

Another trick is to get a large syringe, stretch some hose over the outlet of it, and onto the bleed screw at the caliper. Then you can fill the syringe up with brake fluid and push it through the system from the caliper to the master cylinder. Be careful to "burp" the syringe first to avoid pushing more air into the system.

[racinteach]

The the whole system was bled with a speed bleederand the good ole fashin way.....master never went dry...that I remember...this bike has a story behind it as well. could ithave air of course...try this trick first...tongiht ziptie your front lever tot he bar and leave overnight. by morning it should have forced any air to the top of the master...if it continues give me a call Jay

[harbiho]

I guess it pays to switch to Galfer SS brake lines. They come with a bleeder at the Master Cylinder banjo.

[J.Moto]

The bike has a story, but the front brakes worked perfectly (it's the back brake that was fucked). The original bleed must have not released all the air. I did have help so not to re-intake air into the lines.

Teacher, I'll be in L.A. tomorrow for an interview but will probably come back up to the high desert Saturday morning (after helping a friend with his car tomorrow night). Maybe we can try to re-bleed the system.

Originally posted by harbiho
I guess it pays to switch to Galfer SS brake lines. They come with a bleeder at the Master Cylinder banjo.

I didn't see a bleed at the MC banjo (I did just put Galfer lines on)...

[soulofadra6o]

my speed bleeder didnt fit my SV..but i am having the same problem as you supaphatty...my brakes firmness goes off and on, usually when i first start the bike they are rock hard

[malkey]

Originally posted by soulofadra6o
usually when i first start the bike they are rock hard Nobody asked you about your nipples. :p

[SVNerd]

My money - based on your description supaPhatty J - is first on air in the line and/or caliper, if for no other reason, the most likely/common culprit.

I use both a speed bleeder at the master cylinder, and a MityVac to get ALL the air out.

Based on what 'teach describes however , I'm going to assume your bike has a lot of miles ...

If you're absolutely convinced at some point that you've got all the air out of the system, AND there's no sign of leakage anywhere (check the calipers' pistons too), its possible that the problem is with the master cylinder itself.

I've had near identical issues with both brake and clutch master cylinders, where their seals were simply worn out, or their cylinders were damaged (some can be re-honed) from too much wear (dirty fluid ...). Even a little particulate can also block (or partially block) orifices, causing similar effects.

Bottom line: vacuum flush and bleed thoroughly again (at the master cylinder too). If no leaks anywhere, AND the problem persists, I'd start looking at the master cylinder.

Good luck !

[soulofadra6o]

maybe take apart your calipers, reset the pistons and check your seals to see if any air is getting in them

[harbiho]

Maybe Galfer stopped providing those Master Cylinder bleeders? :confused:

Either way, do what Robert suggested and ziptie the lever to the bar and leave it engaged overnight. That should allow bubbles to be released throught the reservoir.

[chrissilverm]

robert beat me to the zip tie trick......he tought me that. it works.

[Rick Dub]

I don't think anyone has mentioned brake fade.....Is that a possibility? He said it happened after a hard stop.

nevermind.... I just read that he had the same problem the next morning.

[Knaapie]

How can you bleed the stock SV master cylinder? I know there's a bleed nipple on the radial GSX-R cylinders, but haven't seen one on the SV ones.

[Mohawk]

Galfer made bleeders for the master. I don't know if they still do or did for 2nd gen bikes. Heck, I don't even know if there is a diff between 1st gen and 2nd gen masters. I have one on my 1st gen.

[codzilla70]

There are banjo bolts with bleeders on the end. Really helps if your master doesn't have one. Maybe thats what you guys are talkin bout?

[soulofadra6o]

ok, i have a brake problem....my brother took my bike to the shop to get the valves adjusted (while i was still in phoenix) and they installed new rear brake pads...so when i rode my bike while in cali it was fine, and even the ride back to phoenix everything was fine...but the day after i got back they started squeeking...it was a lot, i figured it was the brakes breaking in because my fronts did that when i changed them out a while back. now it's been about a week and they're still squeeking...it's really irritating me because it makes me look like a stupid squid...i took a look and the clearance is very tight, any tricks of the trade to stop it?

[Darth Lefty]

Originally posted by soulofadra6o
ok, i have a brake problem...
Are you or are you not the one going to motorcycle mechanic school?

[soulofadra6o]

yes i am, but just because i am going there doesnt mean i know everything right away

[Dante]

Not sure this will work, but...

take the new pads off, loosen the cap on the master cylinder. Use a wooden block and a pair of vice grips to squeeze the piston *all* the way flush with the surrounding metal. Reinstall pads, wipe off excess brake fluid from around reservoir, see if you still have a problem. Sounds to me like they didn't back the piston back in all the way and now they may be dragging or just not moving correctly.

[Knaapie]

Did they use copper grease on the back of the pads when they installed them? My rear brake also squeeked a while ago, so I took out the pads and applied some copper grease on the back of both pads. After that they stopped squeeking, so perhaps that will work for you as well.

[mother]

I have a similar problem to supaPhatty J but my brakes have gotten very squishy

I have bled the brakes... how do I check the pads...

what gives?

[J.Moto]

Hey man, I can tell you what the result of my problem was.

The pin that holds the pads in untorqued itself and fell out. It took me a couple times of looking the brakes over to realize the pads were freely floating around inside the calipers, something that could have resulted in a bad incident. It kind of messed up the pads for that rotor, too. The loss of brake feel was because one end of the pad was drooping below the piston.

Now if your brakes are installed correctly, it's a different issue.

[mother]

from what I can tell that seems not to be the issue

[mother]

no?

anyone?

I'm not gonna die am i?

[Knaapie]

Perhaps you have a lot of dirt on the pistons and dirt seals. That could cause the brakes to feel squishy. The piston is automatically withdrawn as it sticks to the seals.

[mother]

changed all the hydrolic fluids this weekend...

man what a difference

a spoon full of sugar helps the medicine go down