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Hot Rods Who's running external clutch slaves

Discussion in 'The Hokey Ass Message Board' started by model A hooligan, Apr 28, 2018.

  1. Yeah so a longer fork would be good then?
  2. I don't have these measurements,but now that you have listed it plain as day,I'll need to order a slave and make a new bracket and get those measurements. I can understand that.

    But I'll mention I failed math class hahaha. Autoshop was A++ though!
  3. Yes definitely understand I need to get rid of any slack possible and have the most direct route of pull.
  4. I'm thinking on going with the Cnc pull type. It has 1 1/8 of travel and has lip seal like a wheel cylinder rather than o-rings like the wilwood. I've heard they leak, and the hydraulic throwout bearings leak and both have o-ring seals being the shared design
  5. You sure have more room behind the trans than in front of it. I think you may find some examples here. The topic comes up now and then. How about a cable one? Takes the hydraulics out of the equation.
  6. It makes it easier on the slave then the master then your effort to release the clutch if that's how you wanna see it.
  7. Really?

    I purchased a Cnc 7/8 pull clutch slave this morning. Just gotta wait for it to arrive now. I got the pedal positioned in the car,will report back when I get more progress
  8. Since the rod is inside where the volume of brake fluid is. Perhaps your travel hasn't became less?
  9. Maybe? I've heard that the speedway one doesn't have enough stroke at .88 advertised stroke. The Cnc is advertised at 1 1/8" stroke and has a lip seal and a o-ring,vs most all others are just o-ring.(that was my determining factor over getting the wilwood)

    I've heard something about folks taking out the internal spring to get more movement. But I have no idea if that's true or how much it would gain.
  10. Now you need the bore size of the 1-1/8 stroke cyl to find the volume it requires to move that far.
    Then ,,,
    You need bore and stroke of the master to see if it can deliver that volume required.
    Johnny Gee likes this.
  11. ....and remember to subtract the area of the rod when determining the effective bore size.
  12. krylon32
    Joined: Jan 29, 2006
    Posts: 5,652

    Alliance Vendor
    from Nebraska

    I've used quite a few Willwood 7/8 pull slaves and their recommendation has been their large volume 3/4 master cylinder. That is the MC I've sold with the slave for many years. The large volume MC is the cast aluminum one with the wire bale holding on the top. That's the setup I have on my deuce 3 window and roadster and on my deuce pu I have swing pedals with the Chevy truck MC sleeved to 3/4. All three work great.
  13. So the slave cylinder has arrived. The manufacturer recommends drilling a hole in the fork as close to the bell housing as possible.

    2 questions: 1,wouldn't that make the pedal effort more? I'm assume the say this to get the most travel.

    And 2: they show the threaded rod just going through the hole you drilled. Wouldn't the threads be damaged from vibration just sitting in the hole?

    I'd like to use a heim at both ends but the recommend the drilling a hole and just using the rounded nut on the front of the fork with nothing on the back side. Opinions??
  14. A Chevy rocker arm ball works good.
    slave stuff.jpeg
    Thommyknocker and 40FORDPU like this.
  15. Ended up using brims at both ends. Hope this works. Not sure if the bracket is strong enough or not

    Attached Files:

  16. ^^^^^ I hope the cly rod doesn't flex and bend. :eek:
  17. That's what she said... But it is largely unsupported. Have someone work the pedal and see if it has any flex to it. I mean the rod itself, the bracket might be ok.
  18. ^^^^^ Guess you didn't catch that you can't push on a string put you can pull on it. ;) Yes, mind games :D
  19. What are you guys talking about?? It's installed exactly how everyone else does and exactly how the manufacture suggested it.
    It PULLS
    Last edited: May 8, 2018
    Johnny Gee likes this.
  20. Lol. Read the last three words on post #78. As for pedal effort per your post/question #73. Yes pedal effort is to be expected to become greater. To combat that you can change your pedal ratio or use a smaller master providing enough fluid can still be delivered to the slave for proper slave travel to get things done.
  21. I would check the operation thru the range of motion as the heims are not pivoting radially as they should. Any side load imposed on the cyl will cause grief.

    Other things being equal; the pedal effort will be greater with the 7/8" pull cyl than it would have been with the 7/8" push cylinder due to the smaller piston area.
  22. I think it will be okay. The slave cylinder manufacturer as well as other forums all seem to say the 3/4 master with the 7/8 Cnc seem to be a good combo
  23. I'm using a Cnc pedal assembly. So I'm using their pedal,their clutch slave and a master cylinder that they recommend (3/4)

    They also had listed in the instructions to mount it as close to the bell as possible to reduce needed stroke im
    assuming. Considering I'm doing everything they listed and using their parts.. not really sure what the problem is. May make the trans bracket a bit closer to the trans, but that's only due to the fact it's a studded heim and sticks out farther than I planned (store was sold out of the regular Heims)
  24. I would still watch for flex while it pulls. It my be okay if the heims do their thing and you don't have a bind.
    Joined: Feb 22, 2006
    Posts: 615


    I run some thing sim. Wildwood master3/4
  26. Okay so got the thing done. I thought.

    Rebuild the bracket,it's bulletproof now, bled the clutch system, the pull slave is NOT delivering its full stroke. It only moves about 1/2 inch bs it's 1 1/8 advertised stoke. So it's not disengaging the clutch.

    Also my damn hurst won't go into reverse,though the clutch is a bigger issue.nothing looks like it binds or flexes at all
  27. Ok it's math, all posted before but maybe now it will appear more relevant and earlier post will make sense.

    What is the volume of fluid displaced in the slave for its full 1-1/8 stroke??
    What is the volume of fluid displaced in the master at its as installed available stroke??
    How far does the fork really need to move ??
    get volume =πr(r) h
    Pie (R squared) height ( stroke)

    There's no way out of this without math,
    You'll have to do it or someone is going to have to do it for you.
    I'll wager the master bore needs to be bigger or a pedal re design to stroke further, making it bigger will increase your pedal Efforts required
    Johnny Gee likes this.
  28. How would I know? It's not like they give you that information in the box. I didn't make the master or slave cylinder.

    Can't do anything about the pedal, already is high enough that my knees almost hit the wheel, and it hits the firewall fully compressed
  29. Then the simplest thing to do is try a next size larger master and see what happens. Math is a man made invention so man can have the answer before hand. But!, math does not always give the answer either in some situations. It is then that man has to be willing to compromise. What that compromise is? It's for each to find. But before moving and changing things. Has all the air been bleed out?
    Last edited: May 11, 2018
  30. Master cylinders are not exactly cheap for these.

    Well the fluid comes out with no air so I'd think so.

    The company does say not to use rubber line. I used a small bit at the clutch slave to the floor and a small bit at the master cylinder to the hard line that connects them. I can't get away without it since my master cylinder has to be moved slightly to get my gauge panel in so that's sort of a must. And I figured it had to have it at the slave to body considering the engine vibrates at higher rate than the body

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