HYDRAULIC DISC BRAKES

"John Smith" <[email protected]> wrote in message
news:[email protected]...
> Hope someone can help me out here. I have a Trek 4500 Disc, with hydraulic disc brakes. The
> problem being is that the front brake works superb whereas the back one is giving me
constant
> grief! It is stopping the bike OK, but some of the sounds coming from it
are
> beginning to do my head in! Sometimes there is a high pitch ring coming
off
> the disc and other times a deep noise like you hear on v-brakes when one
is
> coming on before the other. Could this be due to the wheel hub needing to be moved further over to
> one side of the spindle to allow the disc to be dead central to the pads??

What make of brakes and hub?

John

On Thu, 05 Jun 2003 19:54:22 +0000, John Smith did issue forth:

> Hope someone can help me out here. I have a Trek 4500 Disc, with hydraulic disc brakes. The
> problem being is that the front brake works superb whereas the back one is giving me constant
> grief! It is stopping the bike OK, but some of the sounds coming from it are beginning to do my
> head in! Sometimes there is a high pitch ring coming off the disc and other times a deep noise
> like you hear on v-brakes when one is coming on before the other. Could this be due to the wheel
> hub needing to be moved further over to one side of the spindle to allow the disc to be dead
> central to the pads??

The ringing sound is probably something to do with the caliper not being aligned correctly. I can't
remember what sort of brake mount the Trek has on the rear so:

If it's a Hayes mount (bolts going directly into the seatstay) try slackening the bolts off and move
the caliper so that the disc is central.

If it's an International Standard mount (bolts going through a mount that sticks up from the
chainstay) then you need to remove both bolts and either add or remove washers from in between the
mount and the caliper until the disc is central. A handy tip if you're doing this is to stick the
washers together with a little dab of grease, otherwise you'll end up with washers flying
everywhere.

The howling sound is usually down to either a bad choice of pad compound by the manufacturer, or it
can often be solved by taking some copper grease and smearing it thinly on the *back* of the pad.

Huw "Bicycle mating calls" Pritchard

"John Smith" <[email protected]> wrote in message
news:[email protected]...

> I have a Trek 4500 Disc, with hydraulic disc brakes. The problem being is that the front brake
> works superb whereas the back one is giving me
constant
> grief! It is stopping the bike OK, but some of the sounds coming from it
are
> beginning to do my head in! Sometimes there is a high pitch ring coming
off
> the disc and other times a deep noise like you hear on v-brakes when one
is
> coming on before the other.

> Could this be due to the wheel hub needing to be moved further over to one side of the spindle to
> allow the disc to be dead central to the pads??

Depends on the discs I would guess - what system is fitted? I have Magura Julies and they do this
all the time; you can adjust the caliper position using shims at the fixing bolts, and you can clean
and refill the fluid, which makes a bit fo difference, but they drag more than I'd like them to.

I'll not say anything too loudly, mind, because the last week or so they've been perfect.

--
Guy
===
I wonder if you wouldn't mind piecing out our imperfections with your thoughts; and while you're
about it perhaps you could think when we talk of bicycles, that you see them printing their proud
wheels i' the receiving earth; thanks awfully.

"Just zis Guy, you know?" <[email protected]> wrote in message
news:[email protected]...
> "John Smith" <[email protected]> wrote in message
> news:[email protected]...
>
> > I have a Trek 4500 Disc, with hydraulic disc brakes. The problem being
is
> > that the front brake works superb whereas the back one is giving me
> constant
> > grief! It is stopping the bike OK, but some of the sounds coming from it
> are
> > beginning to do my head in! Sometimes there is a high pitch ring coming
> off
> > the disc and other times a deep noise like you hear on v-brakes when one
> is
> > coming on before the other.
>
> > Could this be due to the wheel hub needing to be moved further over to
one
> > side of the spindle to allow the disc to be dead central to the pads??
>
> Depends on the discs I would guess - what system is fitted? I have Magura Julies and they do this
> all the time; you can adjust the caliper position using shims at the fixing bolts, and you can
> clean and refill the fluid, which makes a bit fo difference, but they drag more than I'd like
> them to.
>
> I'll not say anything too loudly, mind, because the last week or so
they've
> been perfect.
>
> --
> Guy
> ===
> I wonder if you wouldn't mind piecing out our imperfections with your thoughts; and while you're
> about it perhaps you could think when we talk
of
> bicycles, that you see them printing their proud wheels i' the receiving earth; thanks awfully.
>
> Thanks all for your tips and advice, as the previous poster said "they've
been perfect" on the way home from work just now, so I'll see what the score is tomorrow and if it
happens again, take heed of some of the advice. The bike is due a six week tune up in a fortnight so
i might leave it to "the experts" to sort out! Cheers, once again, John