HYDRAULIC DISC BRAKES

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

Quoted message said:

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

Quoted message said:

grief! It is stopping the bike OK, but some of the sounds coming from it

are

Quoted message said:

beginning to do my head in! Sometimes there is a high pitch ring coming

off

Quoted message said:

the disc and other times a deep noise like you hear on v-brakes when one

is

Quoted message said:

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:

Quoted message said:

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 hidden]> wrote in message
"]news:[email hidden]...

Quoted message said:

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

Quoted message said:

grief! It is stopping the bike OK, but some of the sounds coming from it

are

Quoted message said:

beginning to do my head in! Sometimes there is a high pitch ring coming

off

Quoted message said:

the disc and other times a deep noise like you hear on v-brakes when one

is

Quoted message said:

coming on before the other.

Quoted message said:

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 hidden]> wrote in message
"]news:[email hidden]...

Quoted message said:

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

Quoted message said:

I have a Trek 4500 Disc, with hydraulic disc brakes. The problem being

is

Quoted message said:

Quoted message said:

that the front brake works superb whereas the back one is giving me

constant

Quoted message said:

grief! It is stopping the bike OK, but some of the sounds coming from it

are

Quoted message said:

beginning to do my head in! Sometimes there is a high pitch ring coming

off

Quoted message said:

the disc and other times a deep noise like you hear on v-brakes when one

is

Quoted message said:

coming on before the other.

Quoted message said:

Could this be due to the wheel hub needing to be moved further over to

one

Quoted message said:

Quoted message said:

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

Quoted message said:

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

Quoted message said:

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