Brakes problem

Is a caliper misaligned? Or any pistons stuck?
Pushing a disc to one side can have the effect of making the brake feel
spongy.

Is there a bubble in the distibuter block? Try bolting a caliper direct
onto the braided hose coming from the master cylinder, putting a piece of
plate between the pads.

HTH

 

Zeroaxe was thinking very hard :

You might try clamping the hose then, which would allow you to
eliminate the possibility of it being the caliper end at fault.

 

Once again I find myself in front of the fountain of knowledge, seeking
advise...

I have some problems at the moment with 'spongy' brakes. I have bleed the
brakes before, without a
problem. So I know I know what I'm doing[1]. I then replaced the seals
inside the calipers, as well as the pistons. The problem then began. I
thought that it might be the hoses, so I got steel braided ones.
Nadda. So I took the bike to the dealer close to where I
lived in London. No result. I then thought it might be the master
cylinder. Replaced that with a R1 assembly. No can do. I took it to
another dealer, without any result there either. So we went on a 3500mile
trip to
France, my rear tyre got slashed, so we stopped at a dealer in
Switzerland. They attempted to fix the problem. Nothing. So just the
other day I had my bike at a dealer in France, this French guy said:"I try.
I fix
it!" <me thinks, yeah right!! give it your best shot buddy!>. Guess
what? Yep! No luck either....

I have had the stock master cylinder on an old set of handlebars in a
vise, with a hose on and one caliper(like a single disk set-up), and
_there_ I can get the thing rock hard[2] but as soon as I put it back onto
the bike, I have no luck.
It cant be the slave cylinder cause I made 100% sure that there is no
air in there [I pumped the brakes, tied the lever up and undo the nut
that keeps the two hoses scrwed in into the slave cylinder, and let
all the air breathe out there. so there is no air there]. I even 'pumped the
brakes and tied up the lever
for three days. [repeated this three times, but it turned out not to be the
lucky number]

I now sit with this dilema of parting with my hard earned cash... Do I
pay the garage to replace the seals again with new ones in the hope
that they sort it out? Or do I go and search for some R1 calipers,
make up some brackets, and mount them to match the master cylinder assembly,
in the hope to sort out this
problem? This is one thing that is realy getting to me, as I have
anylised it as best/much I could, but I cant see the logic/problem
behind this. I followed advice provided on a motorcycle mailing list, as
well as
elsewhere, without hitting the jackpot...

Anyone out there that might be able to shed some light on this and how to
resolve it?

TIA,
Zeroaxe.

[1] Although there are always something new to learn.
[2] Referring t othe brakes on this occasion.

 

recheck all the slides , make sure they are traveling smoothly both ways
are not pitted or scored and they are clean

personaally though i would take it in to a dealership , yes its going to
cost you but they have access to specialist testing facilities that you
dont

Last thing you want is brake failure at 100 mph your a long time dead for
the sake of a few quid

 

sounds like a shagged seal to me
that is passing as the pressure rises
as you brake
try a bolt through the banjowrapped in ptfe tape at the caliper end to
eliminate the lever cylinder end
then strip n clean the caliper and fit new seals
but then agin i know nuffin
i spend most of my time falling off the poxy two wheeled things
Dave

growing up is not an option

 

Sorry, I forgot to mention that it is sliding calipers[only two pistons per
caliper]. They seem to slide ok. There are no signs on the sliding pins of
rust that will keep them from sliding.

I have bolted the caliper drictly to the master cylinder assembly like you
mention, with a piece of plate between. It works ok then, but as soon as I
try to put it back on the bike, it fecks up. This problem only stuck it's
head out when the pistons [damage due to road salt], internal seals and dust
seals where replaced.

I'm up in arms, and so where a total of 9 mechanics[in 4 different shops].

Bugger.

Zeroaxe

 

if they are o rings they fit anyhow
oilseals with flanges rely on the skirt being downward of the pressure so
as it blows the skirt open and forms a seal
the pistons should be smooth with no score marks and move over the full
range of travel
and an R6 front cliper is cheaper than an R1 caliper even tho they are the
same so ive found i suspect a fazer 600 caliper will be even cheaper but i
have yet to explore this
Dave

 

yammyr6 wrote

Maybe not in your case but one option that is open to you, which will
endear you to all and sundry in these parts, is to include at least a
little bit of the post you are replying to.

This and other information for the assistance of newbies is contained
within a document called unsurprisingly the ukrm cbt.

 

Harry, thanks for the response. If you are referring to setting up the
master cylinder assymbly with a hose and no caliper on the end, I have done
that again tonight[well, actually I just put the nut with a few washers in
the stock master cyl., tighten it up, and pump all the air out]. That worked
fine. The problem does not appear to be with either the R1 or stock master
cyl.

The thing is this, even with a mock-up one-disk-setup, there are no fluids
leaking anywhere when testing in the vise. And it works fine. I'm at a loss
at this... Someone I know told me that he had the same problem when he
replaced his caliper's pistons and seals. So he hooked up a R1 master cyl,
calipers[with brackets] and he rekons he can stop his 750 Zephyr on a dime.
This sounds like an odd solution to this particular problem though?

Zeroaxe.

 

<c5hft3$fsk$>:

<snip spongy brake problem>

Champ had this problem with the race bike a while back. It turned out
that the disks were 'dished' IIRC.

 

Steve, I agree. I just wonder to what extent they will have to go to get
this sorted? I do have the option[1] to go to work by cage though. The road
here in France to my work isnt that much torture.

This repair couldnt come at a worse time. We just recently moved to France,
which cost more than expected. Plus my pad in London hasnt sold yet, so we
are scraping through at the moment[2].

Thanks again for the input.
Zeroaxe.
[1] Rather not. I would die without my two-wheel-fix
[2] But it will be another story once it _does_ sell ;o)

 

This makes me think about something else... I havent notice any special
design in the seals that would have them installed in a certain 'direction'.
These seals are new, all round(oh yeah, the problem is on the rear brake too
/ ), but it is possible that one/all got damaged when I installed the
pistons. However, they showed no signs of abuse/wear when I removed the
pistons at one point....

Zeroaxe.

 

An edge may be a problem since the lip of the disk will have a ridge.
But disked meant warped... er, like a disk.

Maybe the old ones could be skimmed?

Yes IIRC.

 

Hmmmm, interesting thought. I will have a peek at 'em in daylight tomorrow
afternoon. I assume the I can put a straight edge to it and see if it is
dished/curved? I also assume that the only way to sort his out is get news
disks? At the time I replaced the brake pads, I thought that slight
dish/curvyness would be sorted by the brake pads wearing out in such a way
to counter/fit into the 'curve'. But I get the idea that I might be
wrong.[1]

Champ managed to fix that problem by just replacing the disks, right?

Thanks!
Zeroaxe.

[1] This wont be the first time either!