Re: Brake Piece

["Joe Zaccaria" <jzaccaria@xxxxxxxxxxxxxx>]

Paul,

Your right.  If the reservoir were smaller than the total system volume
required to make-up for worn pads the resultant effect would be poor or no
braking.  In my case though my bike has only 3K miles on it and I had
complained or marginal brake performance since it was new.  I beginning to
believe the kinked hose theory is the root of all of this.

Zac
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- ----- Original Message -----
From: "Paul Fox" <pgf@xxxxxxxxxxxxxxxxxxxx>
To: <ST@xxxxxxxxxxxxxx>
Sent: Monday, February 12, 2001 1:15 PM
Subject: Re: Brake Piece


> zac -- thanks for the reply...
>  >
>  > There are some basic laws of physics that apply here.  First if there
was a
>  > size mismatch between the master and slave cylinders the brakes would
never
>  > work properly whether or not the pads were worn.  You see one of the
great
>  > benefits of the disc brake caliper system is that they are self
adjusting.
>  > What this means is simply that as the pads wear, the calipers retain a
bit
>  > more fluid so the volume of fluid under pressure required to apply the
>  > brakes never changes.  Therefore the concept of the brakes being less
>  > effective when the pads have worn is an incorrect one.
>
> yes, after sending my question i realized that that would normally be
> the case.  the problem would come if the total volume of the slave
> cylinder with worn pads were greater-than, or maybe even
> nearly-equal-to, the volume of the master.  in that case, pulling the
> lever the whole way in would _not_ yield adequate pressure on the
> pads, right?  the lever would bottom out before the system had
> pressurized.  i'm not saying this is the Sprint problem, i'm just
> pointing it out as a possible design flaw.  this could result from
> a late change in the specification for the pads, for instance -- if
> they had lower wear limits than the system was designed for, the slave
> cylinder would need to be bigger.
>
>  > If you look closely at the reservoir/master cylinder relationship, the
>  ...
>  > ... Any restriction will cause reduced
>  > or inconsistant performance.  Therefore raising the reservoir increases
the
>  > fluid pressure at the inlet of the master cylinder ensuring that only
fluid
>  > will be delivered to the caliper.
>
> this makes sense.  the kinked hose in the stock setup certainly _looks_
> like a bad thing.  i'm sure the designers thought that having the
> top of the reservoir high enough would be good enough, but if people
> find that raising it helps, then it must not be (good enough).
>
> paul
> =---------------------
>   paul fox, pgf@xxxxxxxxxxxxxxxxxxxx (arlington, ma, where it's 25.5
degrees)
>   'oh-oh Sprint RS, '91 VX800, DoD #1462, AMA #545601
>
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