I think there are at least two reasons you need hydraulics for brakes:
1. Mechanical advantage. A relatively small pressure applied by you
to the brake pedal results in a relative large pressure at the brakes.
2. As pointed out below, it's easier to get equal pressure at four
corners with hydraulics.
Note that clutch action does not require either 1 or 2. Also note
that A LOT of cars used cable-actuated clutches at least into the
mid-90s, maybe even up to today. And these were not considered wear
or maintenance items. Heck, until recently, even Porsches used cables
(though those apparently did need maintenance).
At 3:00 PM -0400 7/9/01, GreenBugeye@aol.com wrote:
>In a message dated 7/9/01 1:48:34 PM Eastern Daylight Time,
>Tommy_Samuels@markivauto.com writes:
>
>
> > I've done some digging and a lot of era cars come equipped w/
>cable clutches
> > I'll admit, there are a lot of trucks and SUVs w/ hydraulics (my Isuzu
> > Trooper
> > among them), but I've had very good service and no adjustments required
> > from a
> >
>
>Both of my VWs had cable-operated clutches (85 Scirocco, 95 GTI VR6), as did
>my first car, an 80 Audi 4000. Replaced the cable (along with the clutch) in
>the 4000, but the others were bulletproof. I'm pretty sure the 93 S4 has a
>hydraulic clutch, but I don't open that hood very often. Also, all the
>motorcycles I've had (all Hondas) had cable-operated clutches -- no problems
>there, either.
>
>It always kind of seemed to me that hydraulic clutch operation was just a bit
>unnecessary -- why add a relatively complex system when a cable works just
>fine?
>
>Brakes are a different matter -- I'd guess it's mighty hard to keep four
>cables adjusted to get optimum braking synchronized at each wheel. Plus,
>those cables would almost have to run down the underside of the car, where
>they'd be exposed to the weather and (here, anyway) salt and snow. Yikes!
>
>Chris Eck
>59 Bugeye
>59 TR3A
>93 Audi S4 TQ
>91 Honda CB 750
>
_____________________________________________________________
Jeffrey H. Boatright, PhD
Assistant Professor, Emory Eye Center, Atlanta, GA, USA
Senior Editor, Molecular Vision, http://www.molvis.org/molvis
mailto:jboatri@emory.edu
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