Cable or Hydraulic Clutch

 Been looking into a transmission for a custom build. Can someone tell
me if there are any advantages or pitfalls between selecting a cable
vs. hydraulic clutch setup?

 
rricciardi@cfl.rr.com wrote:

How strong is your grip? Do you have big strong hands? Maybe you could
squeeze 40 pounds and with a 10:1 clutch lever ratio, you might be able
to throw out a mechanical clutch with 400 pounds of force...

What is the spring rate of your clutch springs, and how many are there,
and how much preload is on them? An engineer would need to know all
that to select a cable system or a hydraulic system...

Hydraulic clutches have better pressure ratios, that's why they are
used on a lot of motorbikes...

Suppose you have a 5/8th inch diameter master cylinder piston and a
2-inch diameter slave cylinder. The 5/8th inch diameter piston has an
area of 0.307 inches. The slave cylinder piston has an area of 3.14
inches...

3.14 divided by 0.307 = 10.2

So, if you can push on the master cylinder with 40 pounds of force, you
can get 400 pounds of force at the clutch throwout bearing...

The slave cylinder piston only moves 1/10th the distance the master
cylinder piston moves, but has ten times as much force as you applied
at the piston...

And, your clutch lever has leverage over the piston too, so the actual
effort it takes for your hand to squeeze the clutch lever is going to
be a lot less than what it would take to squeeze the lever of a cable
system...

 rricciardi@cfl.rr.com wrote:

It's not a motorcycle, but I have a 1990 Nissan Pickup with a hydraulic
clutch.
The ONLY thing that's ever failed on this truck is the clutch slave
cylinder.
mike

--
Return address is VALID but some sites block emails
with links.  Delete this sig when replying.
.
Wanted, PCMCIA SCSI Card for HP m820 CDRW.
FS 500MHz Tek DSOscilloscope TDS540 Make Offer
Wanted, 12.1" LCD for Gateway Solo 5300. Samsung LT121SU-121
Wanted 12" LCD for Compaq Armada 7770MT.
Bunch of stuff For Sale and Wanted at the link below.
MAKE THE OBVIOUS CHANGES TO THE LINK
ht<removethis>tp://www.geocities.com/SiliconValley/Monitor/4710/

 
mike wrote:


hydraulic

I have a 20 year old Nissan PU, with nearly 157K miles on it, and I've
been wondering when the slave cylinder is going to give out...

(The first car I ever had with a hydraulic clutch system was a 1957
Jaguar.
It was very difficult to get the transmission to go into first gear
when stopped because it had straight cut gears in first and reverse.
Second, third and fourth were synchromesh. I suspected that I could
help the gear grinding problem by making the clutch release better, so
I rebuilt the slave cylinder and bought a new master cylinder, and
changed the carbon throw out bearing but, it was no use, first gear
continued to grind, it was a feature of that transmission. Wizard
drivers could actually shift into first gear while rolling, but I was
no wizard...)

 

Hydraulic clutches were opriginally supposed to be lighter to operate.
Ho ho ho.

Some people like saying that hydraulic clutches are the only way to deal
with power outputs of 100bhp and over. This is pure crap.

A lot depends on the way the thing is designed. Kawasaki's fuel-injected
Z1300, introduced in about 1984, developed 130bhp and had a cable
clutch, whose actuation (at the lever end) was changed from the earlier
carb model.

If you ever get the chance, look at the handlebar lever, the fulcrum
point, the cable attachment point, and marvel - as I did - at such a
simple and elegant engineering solution.

I don't know any modern hyperbike (say 140bhp-plus) that has a cable
clutch, mind you - but the Z1300 example shows that it may not be
strictly necessary.

My Ducati (see sig) produces about 60bhp, and has a hydraulic clutch
designed for someone who delights in squeezing tennis balls in his fist
for recreation.



--
Trophy 1200 750SS CB750F2 CB400F CD200 CB125S DT50MX
GAGARPHOF#30 GHPOTHUF#1 BOTAFOT#60 ANORAK#06 YTC#3
BOF#30 WUSS#5  The bells, the bells.....