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Hydraulic Hand Clutch

Discussion in 'The Hokey Ass Message Board' started by ChopHoliday, Jan 28, 2009.

  1. RichG
    Joined: Dec 8, 2008
    Posts: 3,919

    RichG
    Member

    Okay, I see what you're saying now. I guess I keep thinking about the '77 Celica that I had with its tiny master cylinder and even tinier slave. It pushed its rod at least 2". Maybe the pressure plate and clutch was lighter than what we are talking about here. I realize that I would also be losing the swing on the master cylinder from the floor pedal too.
     
  2. Goztrider
    Joined: Feb 17, 2007
    Posts: 3,066

    Goztrider
    Member
    from Tulsa, OK

    This is about 1/16 of an inch? Is that all? Wow!

    Don't get me wrong, I'm not trying to contradict anyone here, but I too am learning through watching this thread. The thing I'm sort of thinking - and it may be too complicated or something along that line, but the image of movement I have in my head is that of a compound bow. Lots of pressure, but drawn over a distance. I wonder if through using a cable and pulley type setup if you could essentially turn a shorter throw into a longer action? Perhaps even a bellcrank type setup? And possibly a spring assist once it moves to a certain point - both negative to help release the clutch and positive to help with clamping? Hell, I may even be thinking of a counterweight type setup.

    Bottom line is that I'm just trying to think this through, and expose my ideas to those who know more about it than I do. If I kick the idea out there, and someone else refines and uses it, then its been a useful exchange. If not, then we're all just spinning our wheels.
     
  3. budd
    Joined: Oct 31, 2006
    Posts: 3,478

    budd
    Member

    the canadian diesel smart car has an auto clutch, you put it in gear and step on the throtle and the clutch ingages, i have seen an engine and trans that was removed from a smashed one and its looks like a single clutch setup, i didnt see what operated the pressure plate, they have a 6 speed trans and you can run them by shifting yourself or have the car shift for you, there may be something in this setup that could be transfered.
     
  4. http://www.youtube.com/watch?v=Izc2oTImyjc

    ^ auto clutch for motorcycle, Works well on take off, shifting?? released in 2006 Should be able to replicate the system in a automotive preasure plate, there is a pattent on the automotive aplication in 1999, however I was unable to read all of it.

    http://wiki.answers.com/Q/How_does_...rivers_work_in_a_LHD_car_and_how_is_it_routed
    ^ a wiki answer to handi cap clutch.

    http://www.tbucketeers.com/forum/f18/4-speed-thoughts-2501/
    ^been talked about before.

    http://www.tbucketeers.com/forum/f9/hand-clutch-2523/
    ^and again.

    http://www.patentstorm.us/patents/5996752/description.html
    ^ pattent, uses computers and servos to operate pedal. ( my opinion is that the mechanical advantage gained by the throw of the pedal is greater than a direct elecrtonic servo slave could manage. IDK just an opinion)

    Most handi cap setups utilize the pedal.

    http://www.patentstorm.us/search.html?q=hand+clutch&s.x=12&s.y=6
    ^43000 + hits for hand clutch.

    If There was room in this particular hotrod, Perhaps the Hand operated master could operate a slave > that operated a booster > that operated a second larger bore master> that operated the slave at the clutch. Thats hard to follow read it twice.
    You could put it under the seat, and it would be slow for shifting.
    A Vacume clutch was used many years ago, slow actuation.

    http://www.youtube.com/watch?v=FCfjFUxymSw&feature=related
    one the road improvise but shows the amount of effort needed by the human body to over come the preasure plate on a MINI CAR in a 1-1 ratio.

    Ok I would like to see this work because there are people who would be so happy if they could bang some gears!!! Plenty of coverage on the subject so obviousley there is a need for this application.
    If the mechanical advantage of the pedal is eliminated, it needs to be replace by some sort of booster , motor, Full computer electronis ans servos or linear actuaters,

    I havent seen the application yet, But obviously I'm looking for one.
    Steve
     
  5. RichG
    Joined: Dec 8, 2008
    Posts: 3,919

    RichG
    Member

    See this? This is why I love the HAMB! People working out their ideas, coming to solutions, or at least closing in on them! Who needs engineers, we're car freaks, get the hell outta our way!
     
  6. krooser
    Joined: Jul 25, 2004
    Posts: 4,583

    krooser
    Member

    Old modifieds used a hand clutch...usually an old Ford M/C mounted to the left roll bar upright with a simple steel lever to operate it...
     
  7. The bottom line is this. You cannot get something for nothing. It takes a given amount of force to disengage a clutch. The human hand can exert a given amount of force. Both of these factors are variable according to the pressure plate and the strength of your, individual, pud puller. Even with the lightest clutch and the strongest grip, there is no way to operate an automotive clutch, by hand, without outside help. By hand, I mean with a M/C style clutch lever. You can monkey with linkages and levers all day long, it doesn't matter. Take a gear train, as an example. You have two gears with the same number of teeth. If you mesh them together, the driven gear will turn at the same speed as the drive gear. Now add some gears in between. It doesn't matter how many gears or the number of teeth. The original driven gear will still turn at the same speed as the drive gear. Gears, linkage, hydraulics, it's all the same. Ratios.
    Some type of mechanical booster is necessary, be it hydraulic, vacuum, air, electric, mechanical or nuclear. Some of the V-8 biker guys that I've been in contact with have tried air and electric servo setups. They were not very sucessful. They both lacked the tactile feeling needed for a clutch. Certainly they could have been made to work, but at what cost? Air isn't free, you need a compressor. There are valving issues that would be an engineering nightmare. Electric is no better. There would be a tremendous amount of heat generated by a resistor large enough to vary the speed of an actuator heavy enough to operate a clutch.
    I have a friend that is an avid V-8 biker and a retired NASA engineer. He is, perhaps, the most brilliant man that I have ever met. He has stuff that is on the moon. he has been working on this problem for some time. There are ways to do it and do it well. It's no problem at all. He explained how it could be done, but it went over my head and I was on an 8 foot ladder. The problem comes in at the cost. It's not for Po'Boys like me or the faint of heart. Technology, particularly at the developmental stage, is like speed. I costs $$$. How fast do you want to go?

    The question that I've had, from the beginning is "Why?". I've seen deeply channeled cars and "T" buckets with three pedals. There is room in the car in question for a conventional clutch, brake and accelerator setup, so why mess with sucess and try to reinvent the wheel?
     
  8. HEY ChopinHoliday, are you still around?

    I hear nearly 500 lbs of force on the throwout bearing?
    Some folks are saying its been done but no pics come with the claim?

    If there is no room for a clucth pedal i'm assuming there is not much room anything else.

    What if, only Thinking out loud here,
    the lever hand clutches require two hands shifting or knee steering/driving, or no cluth shifting.
    I've had to do that on an old yard crane not fun at 8 mph.
    Sure that will work.

    Thinking out loud,,,,,
    Three speed trans Correct?
    Two Shift rods Correct?
    Floor mounted shifter Correct?
    Need some kind booster, or mechanical advantage over that clutch

    How about if the shifter becomes the lever needed to operate the clutch, either cable, hydraulic, or mechanical Z bar, Set it up push or pull what ever suits your needs.

    On the trans, loose shift mechanism, and the rods, mount 2 electric linear actuators to replace the rods, Adjust linkage as needed.

    On the shifter grip two buttons, one for up and one for down,

    Pull the clutch lever that looks like the shifter, hit the up button, relase slowly, Pull, tap up button 2nd gear, Pull, tap up button 3rd gear, Pull, tap down button to down shift.

    Will need a few simple limit switches, a few relays, Pretty simple analog control board just lots of steps, Could set it up on a computer board with micro switches. Its only six positions you need to control and should be lightening fast. needs fail safes buit into it.

    Definatly not traditional build by any means, But it does use the same traditional ingenuity and imagination.

    EDIT: Might not be correct for a hot rod, but it might be right for somebody who wants to bang some gears.

    Reinventing the usage of the wheel !!!!!!!!!!

    sure would like to see some pics of that race car a few posts back.
     
    Last edited: Jan 29, 2009
  9. That's thinking outside of the box!!!
    Cord and a few other used an electric shifting mechanism years ago. They didn't work real well when new, but restorers have refined them and made them work reliably. Still, it's a challenge, but probably an easier one. Two small actuators a coupla switches and there ya go. The Cord was a preselector. You could preselect the next gear and it would shift when you stabbed the clutch pedal. A micro switch on the new clutch lever would do the trick.




    What if, only Thinking out loud here,
    the lever hand clutches require two hands shifting or knee steering/driving, or no cluth shifting.
    I've had to do that on an old yard crane not fun at 8 mph.
    Sure that will work.

    Thinking out loud,,,,,
    Three speed trans Correct?
    Two Shift rods Correct?
    Floor mounted shifter Correct?
    Need some kind booster, or mechanical advantage over that clutch

    How about if the shifter becomes the lever needed to operate the clutch, either cable, hydraulic, or mechanical Z bar, Set it up push or pull what ever suits your needs.

    On the trans, loose shift mechanism, and the rods, mount 2 electric linear actuators to replace the rods, Adjust linkage as needed.

    On the shifter grip two buttons, one for up and one for down,

    Pull the clutch lever that looks like the shifter, hit the up button, relase slowly, Pull, tap up button 2nd gear, Pull, tap up button 3rd gear, Pull, tap down button to down shift.

    Will need a few simple limit switches, a few relays, Pretty simple analog control board just lots of steps, Could set it up on a computer board with micro switches. Its only six positions you need to control and should be lightening fast. needs fail safes buit into it.

    Definatly not traditional build by any means, But it does use the same traditional ingenuity and imagination. Reinventing the usage of the wheel !!!!!!!!!!

    sure would like to see some pics of that race car a few posts back.[/quote]
     
  10. Hackerbilt
    Joined: Aug 13, 2001
    Posts: 6,250

    Hackerbilt
    Member

    If you only have room for two pedals...use a hand throttle.
    Over 10,000,000 Model T's had one so it can't be wrong!!!

    Just to add to the thought process...there was a beautifully designed LeMans type car from the teens or 20's...can't remember the name...that had power mechanical brakes.
    The power assist was actuated by having a spinning brake drum driven by the engine and a semi-floating backing plate that could rotate between stops.
    The foot brake actuated the internal brake shoes on the floating backing plate, which caused the backing plate to twist within its range of motion and pull on the cables or rods to the actual 4 wheel service brakes. POWER mechanical brakes!
    I thought it was brilliant...but how long the actuation shoes lasted might be an issue.
    Maybe not if it were just used for clutch actuation.
     
  11. ChopHoliday
    Joined: Nov 5, 2008
    Posts: 40

    ChopHoliday
    Member
    from P-Town, VA

    31Vicky,
    3-speed, 2 shift rods, and on the floor correct. There is enough room on the floor if I really had to use a pedal. However, driving my old man's '32 and having to take my shoes off so I don't hit the brake at the same time sucks. (and because he'd freak if I got it dirty) Coming up with a hand clutch is an idea I got one night drinking beer with one of my boys. After talking with a few people we realized it CAN be done but only a matter of how. This website is absolutely amaizing because all you guys have come up with some really great stuff. I like the idea of using the shifter for clutch and buttons to shift but think I'm going to stick with the hand lever on the shifter. Finishing the floor and steering now and plan to get started on the shifter in a couple weeks. I want to say thanks again to all who posted and I'll be sure to post once we get moving on it.
     
  12. yoyodyne
    Joined: Nov 26, 2008
    Posts: 856

    yoyodyne
    Member

    Quote:
    <table border="0" cellpadding="6" cellspacing="0" width="100%"> <tbody><tr> <td class="alt2" style="border: 1px inset ;"> Originally Posted by yoyodyne [​IMG]
    ... A motorcycle throwout bearing only moves about .065".
    </td> </tr> </tbody></table>

    That's all the pressure plate needs to lift to disengage the multiple plate clutch. I build them, that's why it's on my mind. A car clutch needs less, because it's a single disc. The throwout bearing in a car moves farther than the pressure plate pressure ring moves because of the leverage ratio of the fingers in the pressure plate. I don't have those figures in my head, but it's about .030 movement of the pressure ring, and about 3.5 to 1 ratio. anyone have those exact figures?
     
  13. SPEEDBARRONS
    Joined: Aug 23, 2004
    Posts: 1,248

    SPEEDBARRONS
    Member

    I did it, do a search "BONESHAKER"
     
  14. This is frikkin' IMPRESSIVE!!!! At first I was reading this thread and thinking that if there ever was a place for an automatic trans, this is it. But as I read on I starting seeing what makes the HAMB the greatest forum ever. It doesn't matter that a slush box would be easier, BY GOD WE WILL FIGURE THIS OUT !!!! Just can't beat the folks on the HAMB!!! Keep it up guys!! Thanks, Mike
     
  15. Ok here is is !!

    http://www.jalopyjournal.com/forum/showthread.php?t=160307&highlight=boneshaker&page=3

    Never finished, never driven, you still didt know if you could shift it.

    The left hand lever to pull the clutch is well ove 24" long

    "nothing ventured, nothing gained. The clutch lever still ratchets and locks, just shift fast enough everything should be fine " post#20

    you claimed you did it when you said "I DID IT""refering to a building a working drivable hand clutch in front of 65,000 hambers.

    Over three years in the build and you didnt do it! Take 30 years if you need to finish but you did not build an operable system.

    Excuse me Speednazi I need to call someone !!

    http://www.jalopyjournal.com/forum/showthread.php?t=222275&highlight=boneshaker

    Sold it un finished

    http://www.jalopyjournal.com/forum/showthread.php?t=37470&highlight=boneshaker

    Never could and never did answer all the questions about how you plan on shifting and driving that thing.. I counted at least ten questions about and that subject and the closet thing to an answer was "it should be fine"
    Again i need to call some one !
     

    Attached Files:

    Last edited: Jan 29, 2009
  16. SPEEDBARRONS
    Joined: Aug 23, 2004
    Posts: 1,248

    SPEEDBARRONS
    Member

    Hey smart guy, the car is still up here.....its also not the first one.....and that was an old race car with existing workings....I also went by Barron in the early years, go dig some more
     
  17. i will get to you in a just a moment
     
  18. oldtime
    Joined: Oct 18, 2008
    Posts: 27

    oldtime
    Member

    About forty years ago, I seen a set of hand controls on a '37 Ford. It had a lever for the throttle and a brake on the right side of the column. The clutch lever was on the left, the wild thing was that when you pushed the brake lever it disengaged the clutch, this thing had a virtual jungle of linkage under the floor. The guy that had it had bought it from a guy that had Polio. To shift, you clutched with your left hand and shifted with your right hand, in looking back I wonder if the thought was that the person driving it would short shift so the car would go straight without steering input, so it has been done.

    One way to gain leverage is to offset the center of a sprocket and use a length of roller chain, by doing this, it's possible to vary the pressure or force neede to move the throwout lever.
     
  19. http://www.disabilitymuseum.org/search_lib.php?from=kwlist&q=hand_controls

    ^^^Old disability hand controls that were designed for older vehicles . If duplicated would fit with the period correct ideals. One of them shows two very large actuators mounted under the seat with cables running up front. Most of the others use the clutch pedal.

    http://www.tiltonracing.com/content.php?page=list2&id=30&m=b
    ^^master cyl's need to stroke about an inch
    http://www.tiltonracing.com/content.php?page=list2&id=13&m=b
    ^^pedals give you a 6-1 ratio advantage
    http://www.tiltonracing.com/content.php?page=list2&id=206&m=d
    ^^throw out bearing has a piston area of 1.22 and a max stroke of .77
    http://www.online-calculators.co.uk/volumetric/cylindervolume.php
    ^^cyl volume calculator.
    http://motorcyclebloggers.com/tech-talk-articles/brakes-101/master-cylinders/
    ^^ a very good read and explanation of master cyl sizing and bore and stroke vs effort and hand fatigue with some rebutal and conformation comments from engineers, the theory is the same

    http://www.roadraceengineering.com/clutchpressure.htm
    You can get an idea of the pressure on the throwout bearings here .
    Depends on the lenghth of your pressure plate fingers from the pivot.

    YoYoDyne has some good info here, still not sure,

    "The throwout bearing in a car moves farther than the pressure plate pressure ring moves because of the leverage ratio of the fingers in the pressure plate. I don't have those figures in my head, but it's about .030 movement of the pressure ring, and about 3.5 to 1 ratio. anyone have those exact figures?"

    ChopHoliday, do you have a measurment of how far the bearing moves on your application ? Also need to know the total lenght of your pressure plate fingers and location measurement of the pivots on those fingers to calculate ratios
    Anybody have a number?

    If Yoyodyne's number are correct the bearing moves 0.105 to move the preasure ring 0.030. Its been a while since I watched one move but I think that bearing move closes to 0.50. That makes a huge difference.
    Do we need to move 350-500 lbs 0.105 or five times that 0.50?

    The hydraulic throwout bearings are manufactured with a 0.7 stroke, That would be 7 times the above mentioned amount if we use the numbers we are guessing at. I dont know why they would build them like that if they didnt need to be so. This is another reason I believe that the movement is closer to 0.50.
     
    Last edited: Jan 30, 2009
  20. A few years back I designed and built a machine to test clutches for a firm called ClutchAuto in India, the typical figure for throw of the release bearing was 0.275
    to go from full engagement to disengaged.
    If it takes 500lbs at the bearing, a 10 to 1 ratio means a hand lever which moves close to three inches and requires 50 lbs to squeeze, which pretty well the max you can comfortably apply to a lever.
    As I said before in this thread the only way I have ever got hand operation to work is to fit a race style clutch which has zero marcel and hence requires less than half the travel of a street item, which allows a better ratio and hence brings the force required at the lever down to something which is still heavy but at least is not on the limit of human ablity.
     
  21. gnichols
    Joined: Mar 6, 2008
    Posts: 10,989

    gnichols
    Member
    from Tampa, FL

    Holiday,

    My favorite dirt cars were little modifieds raced in Wisconsin in the 60's. Most had hand operated clutches and from what I gather ran in either 2nd or 3rd only. The MC for the clutches was most often low on the frame and depending on driver preference, either pulled back for neutral and let "fly" to drop the clutch, or vice versa. But they were only used for starts, not driving in traffic.

    Here are a few pix. I hope they load in order so you can make sense of them. On a street car, you might put the MC under the floor near the kick and make the clutch lever in an S shape so you can exit / enter under it. Or perhaps a short lever near the left seat edge down low on the floor so you can get in over it?

    Hope these pix help, Gary
     

    Attached Files:

  22. bump for fresh eyes
    some new thoughts
    a few answers
    and the weekend
     
  23. gnichols
    Joined: Mar 6, 2008
    Posts: 10,989

    gnichols
    Member
    from Tampa, FL

    Forgot to add.... you might want to try this hand clutch idea ICW something like the old Mopar semi-auto trans. My folk's old 53 Desoto had one. You used the clutch between reverse and drive, but when in drive the car shifted up and down thru the forward gears automatically without the clutch and you could stop the car without using the clutch and leave it in drive and then resume forward like a modern automatic, using just the brake pedal (great for stopping on hills, too.) Still, working between reverse and forward gears while parking or backing the would be the big hassle (without power steering or 3 arms) Gary
     
  24. Bump for some info
     
  25. yoyodyne
    Joined: Nov 26, 2008
    Posts: 856

    yoyodyne
    Member

    OK, here's some back of the envelope calculations making some assumptions until we have accurate figures from a long style pressure plate to work with.

    On a motorcycle (e.g. Harley) style clutch hand lever, measured 4" from the pivot on a 6" long lever, the lever moves 2.5". That's about maxed for a normal to large human hand. Measured at that same point, 22 lbs effort is pleasant, 35 lbs is a little heavy, and 50 lbs is geezIhatedrivingthisthing stiff. So lets pick 30 lbs effort as a target, and hope we can get it lower. If you are going to shift and clutch with the same hand, the effort needs to be reasonable, if not downright low, for proper control.

    Supposing (assuming) the throwout bearing needs to move .105", the needed leverage ratio from the lever to the bearing is 2.5/.105 or 23.8 to 1. If you can apply 30 lbs to the lever, you can create 714 lbs (30X23.8) force at the TO bearing. That's the total of all the linkage, hydraulic cylinders, etc. between the hand lever and the throwout bearing. If the leverage in the pressure plate is 3.5 to 1, that means the maximum pressure plate spring load can be 714 X 3.5, or 2499 lbs which is a lot. That makes me think that the 3.5 to 1 ratio and the .105 distance are not correct, judging by what the Boss Hoss riders have to do with power boosters and etc.


    With .275 movement at the bearing, the ratio works out to 9.1 to 1, meaning 30 lbs produces 273 lbs.

    So we need better numbers on the clutch itself to work this out. If you can get the pressure low enough with the dual disc clutch and a reasonable engine, I think you can do without power boosting.

    If the lever is arm actuated, instead of hand actuated, like the frame mounted race car levers, or a lever mounted to the steering column like in a handicapped driver car, you can move the lever a lot farther and the ratio can be considerably higher.

    A lot of the excess movement is to allow for differences in flywheel thickness, pressure plate design, bellhousing variation, etc. I would not read a lot of meaning into that large amount of travel Concerning what the PP actually moves. Just my thoughts.


    BTW, I had a customer with a bonneville streamliner cycle actuate the clutch with an air cylinder. It was nitro fueled and had tremendous spring pressure on the clutch, and very little room to work inside the fuselage. So he mounted a regulator on the tiller which operated the air cylinder and he turned the regulator down to engage the clutch.

    He only used the clutch at the start of the run - not much traffic out there. :D
     
    Last edited: Jan 31, 2009
  26. Yoyodyne, I had alot of those same thoughts and conclusions.
    Comfort and control are paramount as they will lead themselves to safety.
    As extencive as my research has been on this subject, I do not believe this has not been done as of yet.
    However I do believe it is possible.
    We just need some info and hard #s to work off of.
    You are spot on with the theory of your calculations, but as you also have concluded something is fundementaly wrong with the #s we are using, but thing are close enough to potentialy work.

    The info from Thunderace was great. I do not know what the motor specs were for that pressure plate application.

    The links i have included in the post are quite usefull and worth exploring.
    I also have created a new thread to request the needed info, but there is very little activity.
    Thanks
     
  27. rustdodger
    Joined: Jan 17, 2009
    Posts: 275

    rustdodger
    Member

    I had a similar issue when built a sprint 100 (read limited midget) a few years ago. A buddy suggested using an old truck emergancy brake handle. They have a button on them that releases a rachet similar to current hand brakes. you could pull it back and set the lock,move your hand to the shifter to shift then return to the clutch lever relesae the button then move the lever and roll off. For the race car I left in the gear I was going to run so didn't shift under way often. It's pretty busy but not as bad as it sounds it worked in my application. The lever was a couple of feet long and the clutch was hooked pretty close to the pivot so leverage was good enough that it was pretty easy to pull.I think the lever I used was from a '40s dodge 1 1/2 ton if memory serves me right. Everything you needed came off as a unit with a few bolts. I can't speak for your application but for what I wanted it worked great.
     
  28. It's definately possible to hand control a clutch.
    however street clutches have typically 0.065 Marcel,
    which means that the amount of momment required coupled with the force of the diaphram is too great to be operated by a motorcycle style lever mounted on the shift.
    So ether you have to have a longer lever, which is arm operated rather than hand, and can not be mounted on the stick,
    Or you use a race clutch which like a motorcycle clutch has zero Marcel, which reduces the travel, and can just about be operated on a motorcycle lever, bit like an on /off switch till you get the hang of it, but it does allow hand control on a motorcycle style lever, and it's still heavy.
    Only other game in town is servo control, which I would say is probably the way to go, I would just go for a simple motor and lead screw with a couple of limit switches to drive the clutch arm, use a drive board out of a radio controlled toy to control the motor ( big model boats run 20 amp rated boards ) and you can have the clutch finger light without a whole load of hydraulics and complicated stuff.
    Means all you have to run up the shifter is a couple of wires so it would keep it all neat.
     
    Last edited: Feb 1, 2009
  29. sickboy13_1975
    Joined: Feb 25, 2007
    Posts: 1

    sickboy13_1975
    Member

    Just thought I'd throw out some numbers and ideas......

    I like the thought of using
    a hand control master cylinder from a motorcycle on the shifter, but I don't see it working as a stand alone unit, but what if you were to use a two part system, (bike)master/(car)slave and a master/slave (car) system together?
    The bike m/c
    to supply fluid to a primary slave cylinder that would in turn be used to work a "stock type car" master/slave setup. I say this because I don't think the bike m/c would be nowhere close to supplying the amount of fluid needed to move the t/o bearing the needed +/- 3.-.5" to fully disengage the clutch. but thats where the "stock system" would come in.


    lets say a typical bike m/c has a bore of .629

    0.629 inch MC: 0.629 inch master cylinder piston and a 7/8 inch diameter slave cylinder piston so the area ratio is (.629/.875)<sup>2</sup> = .516 This means the slave cylinder piston moves 51% of the movement of the master cylinder piston. Conversely, the force ratio is (.875/.629)<sup>2</sup> = 1.93. This means that the force on the slave cylinder piston is 193% of the force on the master cylinder piston.

    0.629 inch MC:
    0.629 inch master cylinder piston and a 1.0 inch diameter slave cylinder piston so the area ratio is (.629/1)<sup>2</sup> = .395. This means the slave cylinder piston moves 39% of the movement of the master cylinder piston. Conversely, the force ratio is (1/.629)<sup>2</sup> = .251. This means that the force on the slave cylinder piston is 251% of the force on the master cylinder piston.


    I don't have all the numbers and I don't know for anything for certain but I would imagine that on a newer hydraulic clutch the pedal pressure would be around 30lbs??? figuring that it's on a 6:1 pedal ratio, the pressure to depress the clutch master without any lever would be 180lbs. and would need to move the m/c piston around 1.5" If that's the case using a .629 m/c and a 1" slave it would take 71lbs of outlet pressure at the master to disengage the clutch right? not sure how to correct how far the m/c must travel though.......my numbers may be WAY off (which never happens :rolleyes:)



    If the pressure is too high at the hand lever could something like this be used to decrease it and increase line pressure?

     
  30. unfortunately if you read the last line;
    [FONT=Verdana, Arial, Helvetica]A slight increase in pedal travel is required for operation.

    [/FONT]so as usual there is nothing for free.
    Numbers wise 500lbs force, and 0.275 movent at the thrust are good ballpark,
    which what ever you do with cylinder sizes and lever ratios at best gives you a motorcycle squeeze type lever which requires at least 50 lbs force over nearly three inches, which is upper limit for human effort, sure you could start bootstraping vacuum operated servo boosters in the line to try and reduce the effort at the lever, but it's a load of unknowns, at best it's a bodge way of doing things, might work, but the odds are not stacked in it's favour ( how much power can be derived from vacuum ? ) verses a dead simple electric motor driven actuator which can be sized to give plenty of spare power and a neat little control which can mount up on the stick with just a few small wires which could be hidden down the middle of the shifter.
    Or if you are real fixed on doing it hydraulicaly, use a steering pump to provide some oil at pressure and just work the valve that connects that to the clutch slave with a bowden cable from a lever on the stick, that would work out easier than trying to do it with hand effort.
     

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