TRX 850 master cylinder noise + mushy brakes ?

Gday . I've just lobbed onto this group after buying my first decent bike -
a nice TRX850 with magnum pipes (oh joy *slobber slobber drool* what a
freakin' delicious sound !) . I thought I'd open by nagging youse with a
question . The front brakes tend to pulse as the bike comes to a complete
stop (ie the last few metres) but are fine when doing the main braking . It
feels like they're grabbing and letting go about once a second and is
extremely noticeable . The lever also feels pretty mushy . I also noticed
that as soon as you touch the front brake lever when still at speed , there
comes forth a sound from the master brake cylinder on the bars . A high
pitched sound like water being emmitted from a small hole in a hose - not
entirely unlike the bizzing sound an electric circuit makes when being
shorted out .

Now I took it back to the dealer who reckons the brake line needs to be bled
.. He also claims that "a lot of sport bikes make that noise under braking" .
This sounds extremely suspect to me and I am guessing that he will keep
feeding me this line until the warranty runs out , at which point the noise
will suddenly and uncannily indicate a shagged master cylinder .

Does anyone else have a perfectly good sport bike that loudly buzzes under
front brakes ?

Ta for any info , you selfless , caring , sharing people . Feel free to tap
into my extremely and possibly critically-limited motorcycle experience .

Lee.

 

One or both of your front discs could be warped. It'd be a completely
separate problem to the possibly shite state of your brake fluid, which
should, as a matter of course, be changed every few years at most. If
anything, I'd be beating the dealer about the head to do it under warranty,
as they shouldn't've sold a bike with shit brakes.

This pulsing you describe, is it just a sound, or can you actually feel it
at the lever when you brake?

Get your bike and push it around the carpark at work or up and down the
driveway at home and see if the discs make a sound in phase with the wheel
rotation
(silence-silence-silence-scccchhhhkk-silence-silence-silence-scccchhhhkk...)
.. If they do, and the *sccccchhhkk* is appreciably loud, you're up for new
discs. Sorry.

 

Cheers for the reply . The brakes don't make any pulsing *sound* (it's the
master cylinder that makes the whistling sound) , they just feel as if I'm
letting go and reapplying them once a second , which makes the bike surge
and slow , surge and slow ... I don't seem to recall the discs making any
irregular scraping sound as I pushed it around (it's at the dealer now)
because I deliberately listened to it .

 

X-No-archive: yes
sarcasmatron wrote in message

I've never heard a master-cylinder make a peep so I've very curious about
yours whistling!
Clem

 

I'd take it back, urgent safety issue. Warranty also.

Disc/s are warped.

Dont fancy braking hard in slippery/wet conditions. You'll be on your backside.

 

That's fairly normal (the buzzing sound, especially if the brakes are
wet - like just after washing the bike). Both my Blackbird and the
Busa have done it.

Cheer

 

X-No-archive: yes
Kevin Gleeson wrote in message ...

I've certainly heard callipers/pads buzz (and screech, squeal, whine, grind,
graunch, click, clunk, clack and clatter) but I've never heard anything out
of the master-cylinder!
Clem

 

I am assuming that it just appears to be coming from the master
cylinder, that buzzing pad noise is pretty normal. Unless of course it
is from the master cylinder, then I'd definitely be worried

Cheers

 

You have to have the brakes slightly applied to get the full effect of a
disc warp. It sounds pretty much certain that one of both of your discs are
slightly warped. I've had a bike like this before and it didn't worry me too
much, no big hassle. The holes in the discs to lighten them etc will make a
noise when braking, but most bikes are like that, and it shouldn't be that
audible.

BTW, how did you KNOW it was from your master cylinder?? Sounds bounce
around a bit, so it is more likely to be from your front discs themselves,
it seems quite odd that the master cylinder would be making any noise at
all. It's just a piston pushing fluid .. what the??

Cam
'03 954

 

you know they need new pads every now and again

 

If my discs play up the master gets really agro and yells out, "Don't make me
come down there"

Kim

 

Besides the Seals and the springs scraping in there, there's nothing that
can make that kind of a noise in a master cylinder to the best of my
knowledge. The fluid's not under that much pressure to make such a noise and
if it was, you'd be looking at new paint work on the bikini fairing too..
Sounds very much like a warped disc(s), which could be sending feedback into
the lever if they were warped in sync. I agree with the rest, get it
replaced ASAP. Brakes are more important than engines IMHO..

 

But one quick and useful check/fix:

Grab some spraycan brake cleaner.
Spray into/around every floating rivet on each disk.

As you do each rivet, get to with the fingers and ensure the floating rivet is nice and relaxed and floating.

I had the same symptoms as a warped disc but a dial gauge confirmed all in order.

Some/one of thr floating rivet mounts was not as floating as it should have.

 

I had similar symptoms when I had new front discs put on
my bike. Front end would judder and the lever would pulse
under brakes. You could even see where the warp was from
the blueing of the steel from the friction of the pads.

Took it back and they checked the discs and they weren't
warped in the slightest. Refitted them and they were fine.
Seems some shit made it's way between one disc and the
rim when being fitted so there was a high spot.

 

cheers I'll check it when I get it back

 

You can't notice anything under light braking . It is only when the bike is
pulling up for the last few metres that there is *any* efect at all .
Certainly sounds like it was coming from the BMS . I got my head dangerously
and stupid-lookingly close to it .

 

Yeah , obviously . But over the usual verbal instructions/complaints from
one part to its cohorts , the buzzing can still be heard .

 

Eleven is perfect on a green one.
































(Hey sarcasmatron; how about you leave in the bit of the previous post to
which you are referring... And the "Fred wrote:")
Clem

 

etc


yer disc/s are warped
the sound is from the pad/rotor interface and is fairly normal if rotors are
slotted/drilled
mushy (lever is 'spongy', pumping improves feel) is from air in line
excess lever travel (differentiated from mushy as lever gets 'hard')is from
disc warp as pads get pushed back further than designed for
get it fixed under warranty as discs are expensive...try not to accept
straightening as a solution as disc will most likely warp again after a few
good temperature cycles

 

Are we talking whistling dixie here, or more popular tunes,
or what?

G