Nick wrote:
> Henry Frye wrote:
> > am afraid I don't get the logic here. If the rear doesn't lock
> > up, you suggest going with the _smaller_ cylinders.
> > Am I missing something here? I would think you get more stopping
> > power from the 3/4" cylinders...
That's right. Assuming that the travel from the 3/4" cylinders
is sufficient to cause the brakes to engage, you will get more
braking power from the 3/4" cylinders than the 5/8" cylinders.
There are two ways to think of this:
1) The maximum pressure exerted by the brake pedal via
the master cylinder brake line is constant. Since the
3/4" cylinder has a larger surface area in contact with
the brake fluid, more pressure is exerted against it.
2) As Nick points out, the 5/8" cylinder moves farther
than the 3/4" cylinder for the same displacement. Thus,
less force is applied over this greater distance. This
is the "lever effect" that we are all familiar with when
using a longer wrench to free an over-torqued bolt...
The above all assumes that the 3/4" cylinder moves far enough
to engage the brakes. (Which it should, since the amount of
motion required in the brake system to engage the calipers and
shoes is actually quite small for properly adjusted & bled
brakes.)
(Of course, what makes this really confusing is that for better
brake leverage, one wants a *larger* wheel cylinder or *larger
caliper*, but a *smaller* master cylinder...)
--ken
PS: What makes this really confusing is that for better
brake leverage, one can't simply say that a bigger cylinder
gives more leverage. Indeed, a larger wheel cylinder or larger
caliper gives more stopping ability, but one would want a
smaller diameter in the master cylinder, assuming that the
smaller cylinder moves sufficient fluid to engage the brakes...
(Think about it!)
--
Kenneth B. Streeter | EMAIL: streeter@sanders.com
Sanders, PTP2-A001 |
PO Box 868 | Voice: (603) 885-9604
Nashua, NH 03061 | Fax: (603) 885-0631
|