Author Topic: Np Pressure in Rear Brake (Read 6217 times)

Neon Knight · « **on:** 10 June 2015, 05:14:31 pm »

Hello guyz, just like to pick your collective brains. A long time ago I replaced the standard rear caliper on my boxeye with the fazer 1000. I have had no problems with it until recently when I noticed and increasing sponginess and lack of feel from the pedal. I though I should give it a good looking at as the MOT was due anyway. Well I changed the pads, changed the caliper seals and bleed nipples, give everything a good clean and replaced the brake fluid. Should have brakes like newI thought. WRONG. I can get almost no pressure at all in the pedal. have tried adjusting pedal travel and height and re-bled the brakes about 6 times. Nothing seems to be making any difference. Could the master cylinder seals be shot or am I missing something ? Any help would be mucho appreciated. Cheers

anutz · « **Reply #1 on:** 10 June 2015, 08:05:45 pm »

i use a combination of the bleeding from pumping the lever and opening/close the bleed screw but ALSO i took out the pads at one point and then pushed the pistons all the way back in.....then bled normally again....seemed to help mine a lot....but will know in the morning...

Fazerider · « **Reply #2 on:** 10 June 2015, 08:19:02 pm »

The master cylinder seals could probably do with replacement if they're the originals still, but most likely it's just air in the system. The rear is a bastard to bleed because the path the fluid follows goes up and down so air can get trapped easily.
Taking the caliper off can help, as can cracking open the top banjo on the master cylinder to push out the air that gets caught there.

unfazed · « **Reply #3 on:** 10 June 2015, 08:20:35 pm »

Makes bleeding easier if you push the pistons back full and clamp them in place.

anutz · « **Reply #4 on:** 10 June 2015, 08:37:40 pm »

anyone ever reverse bleed i.e. push fluid in from the Bleed Nipple???

I have never done it...

unfazed · « **Reply #5 on:** 10 June 2015, 08:48:11 pm »

Yeah!, had to do it on a guzzi a good few years ago, but was a pain in the arse, the dozy pillock

who was with me was talking instead of watching and the master cylinder overflowed, but we were lucky as the tank and was covered and the mudguard which got most of it was chrome

anutz · « **Reply #6 on:** 10 June 2015, 08:57:21 pm »

...but did it work, was it any more effective than the standard methods?

Aside from your awesome assisant....

sinto · « **Reply #7 on:** 10 June 2015, 09:29:14 pm »

Quote from: anutz on 10 June 2015, 08:57:21 pm

...but did it work, was it any more effective than the standard methods?

Aside from your awesome assisant....

There was a thing about this in a recent RIDE magazine, April edition I think???? I'll need to check it tomorrow as its in my works bag for reading while on my break etc

anutz · « **Reply #8 on:** 10 June 2015, 09:40:03 pm »

well Neon Knight....my rear won't bleed up.....just tried it...

Do not really want to take the wheel out which i would need to do i think to get the caliper above the cylinder....

unfazed · « **Reply #9 on:** 10 June 2015, 10:16:49 pm »

Quote from: anutz on 10 June 2015, 08:57:21 pm

...but did it work, was it any more effective than the standard methods?

Aside from your awesome assisant....

No difference just thought it was more awkward, I never did it again.
I use a Mityvac now which makes the job quicker, just have to remember to keep the master cylinder topped up

anutz · « **Reply #10 on:** 10 June 2015, 10:19:22 pm »

Quote from: unfazed on 10 June 2015, 10:16:49 pm

Quote from: anutz on 10 June 2015, 08:57:21 pm
...but did it work, was it any more effective than the standard methods?

Aside from your awesome assisant....

No difference just thought it was more awkward, I never did it again.
I use a Mityvac now which makes the job quicker, just have to remember to keep the master cylinder topped up

Is the Mityvac good - i mean is it one of those tools you can reliably use the same way each time and the jobs done....no messing with changing heights of cylinders or calipers etc.....

I am tempted with a vacuum kit as i do think i will do all my own work as i am doing, and whilst a spanner will do with some tube i would like to make things as painless and simples as possible

unfazed · « **Reply #11 on:** 10 June 2015, 10:24:36 pm »

I found it to be a great piece of kit, a bit fiddly until I got used to it. Keeping the container upright was a bit of a pain at first

red98 · « **Reply #12 on:** 11 June 2015, 06:49:45 am »

Quote from: anutz on 10 June 2015, 08:37:40 pm

anyone ever reverse bleed i.e. push fluid in from the Bleed Nipple???

I have never done it...

big fan of reverse bleed

......this method has never failed me.....i use a pump action oil can with a snug fitting rubber hose....works for me

Deefer666 · « **Reply #13 on:** 11 June 2015, 07:01:44 am »

Just a thought, Is the pin that holds the pads in good condition? They develop grooves over time and the pads will sit in those grooves and be unable to slide back and forth. So the pistons only half push the pads and then they immediately go back to the outside position once the pressure is released and this gives a spongy feel on the pedal/lever.....

darrsi · « **Reply #14 on:** 11 June 2015, 07:26:59 am »

Sounds like you may have done it already, but if you've never cleaned inside the pivoting part of the foot brake lever that can also make it feel spongy.
Either brake cleaner or WD40 will clean any crud out, then i normally drop a bit of 3 in 1 oil in the joint, about once a month.
It makes a world of difference in braking sharpness in traffic.
Worth doing anyway as regular maintenance.

anutz · « **Reply #15 on:** 11 June 2015, 07:58:07 am »

not sure if Neon Knight has done this but i have not so may take a look at some point.

Quote from: darrsi on 11 June 2015, 07:26:59 am

Sounds like you may have done it already, but if you've never cleaned inside the pivoting part of the foot brake lever that can also make it feel spongy.
Either brake cleaner or WD40 will clean any crud out, then i normally drop a bit of 3 in 1 oil in the joint, about once a month.
It makes a world of difference in braking sharpness in traffic.
Worth doing anyway as regular maintenance.

anutz · « **Reply #16 on:** 11 June 2015, 08:00:14 am »

Quote from: Deefer666 on 11 June 2015, 07:01:44 am

Just a thought, Is the pin that holds the pads in good condition? They develop grooves over time and the pads will sit in those grooves and be unable to slide back and forth. So the pistons only half push the pads and then they immediately go back to the outside position once the pressure is released and this gives a spongy feel on the pedal/lever.....

Good point, also something Unfazed mentioned in another thread to me i got my caliper from the USA and the pins are not in fantastic shape, i did wet and dry them, however they may actually still have enough of a groove to cause issues, so i have ordered some new ones, cheap enough and will put them on as well...

anutz · « **Reply #17 on:** 11 June 2015, 06:15:28 pm »

Quote from: red98 on 11 June 2015, 06:49:45 am

Quote from: anutz on 10 June 2015, 08:37:40 pm
anyone ever reverse bleed i.e. push fluid in from the Bleed Nipple???

I have never done it...

big fan of reverse bleed ......this method has never failed me.....i use a pump action oil can with a snug fitting rubber hose....works for me

i may have to try this but right now my banjo bolt it leaking and i cannot be bothered with the bike!!! argh!

stepping away from it for a little but got my clylinder head back so can do some engine work!

anutz · « **Reply #18 on:** 11 June 2015, 08:10:55 pm »

OK so got enthused again...

Took the torsion bar off - hope thats what its called, the bar stabilising the rear caliper mount bracket

Hammerting that as we speak - and a word of note, cooking oil cleaned up my hammerite bruishes wonderfully....no more hammerite = throw brushes away!

Then could undo the caliper and feed it up through the wheel assembly behind the swingarm keeping the hoses attached...

Then made this amazing little tower from a PC and strimmer box....you might not get the same results if you don't use these exact objects..

Highest point is now the Caliper and the tube letting air out of it...

Began to firm up and lots of air rushed out, now at least it has some nice feel....not rock solid yet but have hung a weight off the pedal for now...

Fazer Forever · « **Reply #19 on:** 13 June 2015, 09:29:21 am »

I did the same with mine. Faffed about for ages at first with no sign of any improvement, then asked a friend of mine who's an ex BSB mechanic.
He suggested this method of taking the caliper off and it worked fine, as you've found.

midden · « **Reply #20 on:** 13 June 2015, 10:23:41 am »

Quote from: anutz on 10 June 2015, 09:40:03 pm

well Neon Knight....my rear won't bleed up.....just tried it...

Do not really want to take the wheel out which i would need to do i think to get the caliper above the cylinder....

turn the bike upside down on to handlebars and seat.

anutz · « **Reply #21 on:** 14 June 2015, 01:01:35 pm »

i these bleed nipples don't stop leaking i might just turn it upside down anyway...

going to use my torque wrench to set them as recommended and check i am not under tightening them ( thanks Sinto.....)

i am not sure with these little buggers, they do not have much feel like a normal bolt...