Baffled by Brake problem (Help?)

The story so far:

Callipers flushed through with brake fluid before taking old brake lines
off.

Problems noticed whilst doing that:
* Not much pressure in the system - It would pump fluid through an open tube
but not through a Motrax 'Little Bleeder' one way valve thing. I put that
down to the fact that the existing line was oozing fluid out round its
joints instead. (I'd slackened them off and maybe not been retightened them
fully. Its not the Little bleeder valve - that was checked today on another
bike and reported OK).

* Only one piston on each caliper seemed to move freely after all had been
pushed back in - Got them all freed off and cleaned up too but can't be
totally sure they're not still a bit sticky if not stuck - They shouldn't be
but I dunno they're not sort of thing.

* TBH Trying the callipers without brake pads in managed (cough, blush) to
eject one piston from the caliper and had to shove it back .... Well yeah
but what else was I s'posed to do with it? I *think* I got all the air out.
...... eventually.


I've now put the new brake lines on.
There are no obvious leaks .....
..... but then again the problem now is there's virtually no pressure.
On an open line pumping the hand lever shoves a couple of centimetres of
fluid up and down the tube but it can't fill the short bit of tube from the
bleed nipple to the Little bleeder's valve.

My best guess is either:

There's a load of air still in the new brake lines - But if so why the ****
won't it pump out?

The lever / master cylinder isn't pumping properly - But I'd have thought it
would either work or fail, not pump feebly.

All ideas from the well informed to the bizarrely possible to a newsgroup
near here please.


--
Nidge
ZX6R J2 Stunning in zit yellow. KX 125 MX 'I'm snot green -fly ME'. A few
bits of CB500S in Norwegian Parrot blue. BOTAFOT#63, BOMB#5

'Just because I don't care doesn't mean I don't understand'.
Homer (Simpson).

 

Because its stuck somewhere.

Here are some things you could try:
1. Beat the calipers with a mallet while pumping the lever. After a
while you should start to see bubbles coming up in to the reservoir on
the return stroke.
2. Tie the lever back overnight.
3. Get a syringe and reverse bleed from the bleed nipple (messy)
4. Give up, you've broken the bike irretrievably. I'll give you a
fiver for the scrap.

--
ColonelTupperware
spouting bollocks on Usenet since 1997
Usenet FAQ at
http://www.its.caltech.edu/its/services/internetapps/news/news2.shtml
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UKRM FAQ at http://www.ukrm.net/faq/

 

I've had this problem before with new lines, solved quickly by deft use of
a Mityvac.
Essential bit of kit for brake refurbishment.

Try taking out the bleed valve completely, see if you can get fluid down
the lines by gravity.

 

Do the job right, strip the caliper back to pistons, seals, body. Clean
the grooves the seals sit in until *all* of the oxide is removed, I use
scouring pads. Clean the seals in brake fluid or (if possible) buy new
ones, clean the pistons with brake fluid until looking new, reassemble
and bleed from scratch, it should only take 30mins max to flush the
entire system.

If there is any noticeable damage to any components which cannot be
removed i.e. rust on the piston, then replace said component at the
earliest opporchancity.

Check for leaks under pressure.

[sniip]

You may not be giving the system time to settle, leave it for an hour or
so and the bubbles should rise to the highest point as one big bubble
instead of lots of little ones.

no, they can be fucked and will generate a lever for a short while then
fade. If in doubt get a new one.

--
Martin:
"For a minute there, you bored me to death."
VTR1000 Firestorm
TDR250 http://ukrm.net/BIKES/Yamaha/tdr250.html
martin dot smith nine zero three at ntlworld dot com

 

i had to do the brakes on my bike only half of the pistons worked. What
happens is your dust and oil seals fail and the pistons start to rust behind
the seals and then become stuck this will prevent your break pads from
wearing out evenly.

Things you need to buy.
break and clutch cleaner.
caliper dust and oil seals for each piston. and any rubber seals you come
across
wd40.
dot 4 break fluid.
new break pads.
copper grees

Take the calipers of the bike and remove the pads pull ur break leaver till
the pistons start to poke out if some are stuck u need to stick something in
there to prevent the ones that do move from moving i stuck a pair of pliers
in there then pull leaver till the stuck ones move out so u can pull them
out later if you have twin disk's do each set of calipers one at a time.
take ur calipers apart remove pistons and the rubber seals get some break
and clutch cleaner and clean and remove any oxide get a wire brush and clean
the pistons get everything clean then clean with break fluid. put new rubber
dust and oil seals these have top be repalced. put them all back to gether
with new pads. dont foregt to put copper grees on the back of the pads where
they meet the pistons and on any screews and bolts etc.

Now to bleed new break fluid. get a short plastic tube and put it on the
bleed niple turn bleed niple half a turn. fill resevour with break fluid
pull leaver put thinger on end of tube release leaver take finger off tube
and pull leaver put finger on tuber release leaver check resevour and repeat
this till break fluid comes out of tube with no air bubbles then tighten
bleed nipple

 

i had to do the brakes on my bike only half of the pistons worked. What
happens is your dust and oil seals fail and the pistons start to rust behind
the seals and then become stuck this will prevent your break pads from
wearing out evenly.

Things you need to buy.
break and clutch cleaner.
caliper dust and oil seals for each piston. and any rubber seals you come
across
wd40.
dot 4 break fluid.
new break pads.
copper grees

Take the calipers of the bike and remove the pads pull ur break leaver till
the pistons start to poke out if some are stuck u need to stick something in
there to prevent the ones that do move from moving i stuck a pair of pliers
in there then pull leaver till the stuck ones move out so u can pull them
out later if you have twin disk's do each set of calipers one at a time.
take ur calipers apart remove pistons and the rubber seals get some break
and clutch cleaner and clean and remove any oxide get a wire brush and clean
the pistons get everything clean then clean with break fluid. put new rubber
dust and oil seals these have top be repalced. put them all back to gether
with new pads. dont foregt to put copper grees on the back of the pads where
they meet the pistons and on any screews and bolts etc.

Now to bleed new break fluid. get a short plastic tube and put it on the
bleed niple turn bleed niple half a turn. fill resevour with break fluid
pull leaver put thinger on end of tube release leaver take finger off tube
and pull leaver put finger on tuber release leaver check resevour and repeat
this till break fluid comes out of tube with no air bubbles then tighten
bleed nipple

 

"Chris Griffiths" struggled to ejaculate:

<sniperoo>

Gibberish, meet ... err ... Gibberish!

 

This is bollocks. If the seals fail, your brakes fail. And many modern
bikes don't have dust seals, unfortunately. Corrosion builds up *in
front of* the seals - where the water can get at the surface.

<snip>

Sounded correct but I sort of lost the will to live while trying to read
it.

 

Take a deep breath, OK?

Right. So you cracked the unions off before you removed the lines,
then flushed the system with new fluid. Strange, but never mind. You
will have introduced air at that point and if the unions weren't
retightened fully, you'll have been losing pressure there as well as
letting more air in every on every return stroke of the lever.

If there is corrosion behind the dust seals then the pistons may still
be sticky. If you cannot be sure, go back and do it again until you
are sure.

You were lucky to get the ejected piston back in, mate. There will
have been a huge bubble of air behind that piston however - did it
push all the way back in, so it is known to be in square?

That's because there's /loads/ of air in the system. Did the level of
fluid ever (at any point) fall to the bottom of the master cylinder
reservoir? If so, then there's *loads* of air in there.

Because you cannot get enough pressure on it to move it. Like a
self-fulfilling prophecy.

It probably is pumping properly, but if it is full of air at the top
you won't get much fluid movement lower down.

There is no quick fix, Nidge. Go right back to basics. I hope you
pulled the lever back to the bar and secured it there overnight,
because that is a good starting point. In any case, I'd start with
the right hand caliper, simply because it is easy to get at both the
nipple and the lever on your own.

Forget all the eezi-bleeder shite. Get a little spanner on the nipple
and pull the lever in to the bar, then crack the nipple 1/4 of a turn
and retighten it before you let go of the lever. Keep on doing that
until fluid starts moving. It may take some time.

What you need to do is get some tiny amount of pressure in the line
before you crack the nipple and retighten it immediately. Take it
steady and do not rush it. If this does not work all is not lost,
however:

Method 1. Re-fill the reservoir to the top and take the nipple out.
Let gravity do your work for you. Fluid should start to ooze from the
nipple hole and then you have a fighting chance. Replace the nipple
and bleed the line through as above.

Method 2. Alternatively, take a long piece of clear tubing (car
windscreen washer gear is good) that fits /tightly/ over the end of
the nipple and jam it /tight/ over said nipple. Check the reservoir
is full to the brim. Get your gob on the other end of the clear tube,
and ...
Suck. Gently. Watch the fluid in the tube, you really don't want a
mouthful of it. You should be able to get enough fluid through to
carry the air with it, without having to buy a Mityvac.
Repeat with the other side/other nipples. You should be able to get a
lever at this point.

Method 3. Many rags required. Bleed the master cylinder by cracking
the banjo attached to it. Repeat with every joint, moving down the
lines one at a time slowly and methodically. Once confident there is
/no/ air in the lines, suck fluid through the calipers as 2.

Wash the front of the bike thoroughly afterwards.

Best of luck.

 

snip

Combining arspeckeds of the above with MB's ideas I:

Tied the lever back overnight. Then, leaving the lever tied back -
Opened the bleed nipples (one at a time), attached a very large (80ml)
syringe that SWMBO had in the kitchen for some culinary purpose [1] and beat
the calipers with a bit of wood whilst using the syringe to suck brake fluid
and a fair few bubbles. Then pumped away at the brake lever again.

And now it works

I've a suspicion Roast Potatoes in our house may never be the same again.


[1] Well, the brakes are on her bike.

--
Nidge
ZX6R J2 Stunning in zit yellow. KX 125 MX 'I'm snot green -fly ME'. A few
bits of CB500S in Norwegian Parrot blue. BOTAFOT#63 BOMB#5

'Just because I don't care doesn't mean I don't understand'.
Homer (Simpson).

 

its not bollocks as it happend to my bike, i did not notice it till i was
having new tyers fitted to my bike and stuck my head in there to have a look
at my break pads

 

pip think ur gay or got a problem you spying on me again

 

Chris Griffiths says...

Listen fuckwit, if your seals fail they leak, your brakes (note
spelling) fail and you end up being a trucks bonnet ornament, even if
you have new tyres (note spelling).

Simple as.

 

Chris Griffiths says...

In English please?

 

ok what if they fail just enough to let water in and carode the pistons

 

if you open anything up that has a rubber seal the seal must be replaced.
dont **** about with your brakes theres no easy way out with them anchors
took me 7 hr's to sort mine out on a sundays morning dint even get to pub
that day pissed right off

 

Exactly what I was thinking.

 

Chris Griffiths says...

Physically impossible, I'd have thought. If something can go in that
easily, then it stands to reason that something can come out just as
easily.

 

In my experience, it's the aluminum behind the first seal that corrodes,
and coats the chromed piston in oxide shit. The aluminum oxide that's
coated the piston is also pressing the seal harder onto the nicely
cruddy piston, so your brakes seize up.

 

Yes it is, fuckwit.