Im toying around with an idea.

How much pressure is in a typical clutch line? Im talking about a hydro tranny of course, how much pressure does the slave cylinder see?

 

Just approximate it from

foot pressure(guesstimate) * the clutch pedal arm multiplier ratio(look under your dash) / piston area of the clutch master cylinder.

 

anyone know any numbers? im not around my car.

i see brake pressure gauges are manufactured to go up to around 2000 lbs

 

I can't believe it's any higher than maybe 300 psi. Way lower than 2000 psi. Brakes operate at much higher fluid pressure than clutches.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by B18EG6 &raquo;</TD></TR><TR><TD CLASS="quote">anyone know any numbers? im not around my car.

i see brake pressure gauges are manufactured to go up to around 2000 lbs</TD></TR></TABLE>


Brakes have a booster, clutches don't.

 

I can't answer for any situation except my old DSM. Due to a very common clutch pedal problem on 1G DSM's I actually shimmed my clutch slave cylinder. My first attempt at a shim was to place a penny between the slave cylinder plunger and the clutch arm, the plunger went through the penny in short order. I replace it with a Nickel. The slave plunger put a massive dent in it in very short order. In other words, an ***-load of pressure.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by tjbizzo &raquo;</TD></TR><TR><TD CLASS="quote">


Brakes have a booster, clutches don't. </TD></TR></TABLE>

alrighty, id like a more quantitative answer.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by RevenantAE &raquo;</TD></TR><TR><TD CLASS="quote">I can't answer for any situation except my old DSM. Due to a very common clutch pedal problem on 1G DSM's I actually shimmed my clutch slave cylinder. My first attempt at a shim was to place a penny between the slave cylinder plunger and the clutch arm, the plunger went through the penny in short order. I replace it with a Nickel. The slave plunger put a massive dent in it in very short order. In other words, an ***-load of pressure.</TD></TR></TABLE>

awesome, that gives me a nice(r) idea of the pressure involved...

anyone know a ballpark figure?

 

doubt its much.

With the brakes you are trying to push the pads against the rotor as hard as possible. The more brake line pressure you can apply, the more brake torque will be resulted.

The clutch you are simply moving the clutch away from the flywheel.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by tjbizzo &raquo;</TD></TR><TR><TD CLASS="quote">Just approximate it from

foot pressure(guesstimate) * the clutch pedal arm multiplier ratio(look under your dash) / piston area of the clutch master cylinder. </TD></TR></TABLE>


(~40 lbs pedal pressure)*(~3:1 lever ratio)/(~0.66 sq. in. piston area) = ~180 psi.
There.

 

Actually don't you need to multiply by the master cylinder piston area and divide by the slave cylinder piston area?

Yep.. here it is on p383 of the physics book in fluid statics section
Once you have the force seen at the master cylinder 'F', you multiply by the Master cylinders piston area and divide by the slave cylinders piston area.

 

Um...read the textbook a little more carefully. That's to find the resulting force on the slave cylinder piston. All he wanted to know was the hydraulic pressure inside the line, which is what I gave him. I hope you don't have a physics test soon.

 

ow much pressure does the slave cylinder see
I haven't had a physics test in about 12 years, but I passed them all.

My turn to rib..... Hope you don;t have a reading comprehension test anytime soon

 

haha fock...


whatever, i wanted to see if theres a valve strong enough to withstand the pressure of the clutch line.

i was asking both pressure in line and pressure that the slave cylinder produces, i had two different ideas

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by B18EG6 &raquo;</TD></TR><TR><TD CLASS="quote">whatever, i wanted to see if theres a valve strong enough to withstand the pressure of the clutch line.</TD></TR></TABLE>That might be a little bit different. Depending on what you think you're gonna do...

The reason WHY clutch fluid pressures are so low, is that there's not much resistance behind the clutch. You push it down, & the throw-out fork never comes up against a fixed barrier. Then the pedal hits the floor, but the fluid pressure doesn't get any higher. The fluid pressure is controlled by the pressure-plate spring & it's limited by the fact that the pedal runs out of stroke before the t-o-lever hits something.

Now imagine that you install a shut-off valve in the clutch line. Then close it off. Now when you press on the clutch pedal it's hard like the brake. If you press real hard, you'll be able to develop much higher pressure than normal. A plumbing store valve won't cut it. But there's several companies making valves for high pressures.

Another way of understanding this... Look where the clutch throw-out fork comes out thru the bellhousing. Imagine you're gonna put a steel wedge behind the lever, so it can't move. Again, your clutch pedal will be hard like your brakes. If you stand on the pedal you'll be able to develop real high fluid pressure & high piston force.

If you're doing something like this, use tjbizzo's equation but use 200 pounds or whatever you think your leg strength really is...