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Please school me on hydraulic clutches

Discussion in 'The Hokey Ass Message Board' started by Tugmaster, Feb 2, 2011.

  1. I am putting a manual trans in my new project I am thinking a hydraulic clutch may be the way to go instead of doing with a mechanical linkage. I have never messed with a hyd. clutch before and don't know alot about them. Here is what I "THINK" I know.

    I need a hyd. clutch cylinder. Kinda like a master cylinder. To actuate the clutch I can either use a slave cylinder to actuate the stock clutch fork or go with a hydraulic throwout bearing and do away with the stock clutch fork. If I go with a slave cylinder I will need to fab a mounting bracket for it on the side of the trans.
    Are their and advantages/disadvanteges to either setup? Thanks as always, Todd
  2. RichFox
    Joined: Dec 3, 2006
    Posts: 10,020

    Member Emeritus

    I use the slave cylinder mounted forward of the bellhousing as my clutch linkage was a push rod. I have used the internal throwout bearing type. The thing I don't like about them is if it develops a leak or other malfunction. You have to pull the transmission to get at it. And I have had to. The slave cylinder is right there and easy to get at for bleeding or replacement.
  3. Deuce Daddy Don
    Joined: Apr 27, 2008
    Posts: 5,222

    Deuce Daddy Don

    Been running one out of a 1961 Ford Econoline (Swinging pedals & slave cyl.) for 300,000 miles now, I am a believer, especially for easy adjustments.
  4. jrod60
    Joined: Jul 20, 2005
    Posts: 89

    from Katy, TX

  5. J&JHotrods
    Joined: Oct 22, 2008
    Posts: 549


    Some friends and I have had good luck with chevy S-10 clutch m/c's and slaves by welding a bracket on the bellhousing to mount the slave and use it to push a traditional clutch fork. That would be a real cheap and easy way of doing it. May not look the tidiest though(these were on demo derby cars-made it easy to transfer drivetrains to the next car). On the wagon, we're using the tremecTKO 5 speed with the hyd. throwout bearing. Get your clutch pedal linkage geometry correct too.

  6. JohnEvans
    Joined: Apr 13, 2008
    Posts: 4,883

    from Phoenix AZ

    Match the MC and slave bores. MC is usually about 1/16 larger than the slave.
  7. CutawayAl
    Joined: Aug 3, 2009
    Posts: 2,144

    from MI

    The bottom line is that you want the clutch to fully release with a little clearance, but not to the point that the pressure plate travels too far with the pedal fully depressed. That is especially critical with a diaphragm type pressure plate. With a fully bled system, and the pedal all the way down, you don't want much more than .040" open space between the pressure plate and the flywheel or pressure plate. The linkage ratio of the slave cyl to the release fork can be changed as needed, and/or the size of master cly to slave cly bore can also be juggled as needed to achieve adequate but not excessive releasing of the clutch.
  8. badsco
    Joined: Jun 11, 2009
    Posts: 104


    X2 with the S10 setup. I am using a 95 2.2L master/slave and it is a sealed unit - no bleeding required, but you'll be limited in distance between master and slave as you cant modify the (plastic) line
  9. ClayPigeonKiller
    Joined: Mar 3, 2010
    Posts: 203


    Just buy one of those.

    External slave is the way to go, internals are a bitch to replace. Speedway also sells slave cylinders but we've always been able to find another one laying around.

    There are two types, push type and pull type, the difference is obvious. Which you use depends on your application and mounting system.

    As with any hydraulic system, the pedal pressure and travel distance depends entirely on the size of the bore of the mastery cylinder and the slave cylinder.
    Get the master too big/slave too small and there will be a ton of pressure and little travel.
    Get the master too small/slave too big pressure will be little (usually a good thing) and there will be a lot of travel. But, if the master is small enough it won't release the clutch.

    Kind of Hack-ish but if the pedal it too high or low you cut/add to the rod on the Master.

    Hydraulic clutches work just fine, I prefer them because of the simplicity of the system.
  10. CutawayAl
    Joined: Aug 3, 2009
    Posts: 2,144

    from MI

    :)Right idea but.....
    - big master w/small slave = higher pedal effort and more slave cyl travel

    - small master w/big slave = lower pedal effort and less slave cyl travel
  11. ClayPigeonKiller
    Joined: Mar 3, 2010
    Posts: 203


    Should have clarified, I meant pedal travel. So, we're both right
  12. This is a Tilton set up on a car I'm building for competition, nice stuff but it gets kind of spendy by the time you buy the front bearing retainer that goes with the slave on the internal type.
  13. fleetside66
    Joined: Nov 20, 2006
    Posts: 2,688


    Todd, I did the whole thing for the first time & everything seems to be functioning properly. As far as the slave cylinder bracket goes, I bought one from a company that had all of the geometry & engineering built into it. They only had them for an sbc with certain common bellhousings. It was a bit pricey, however. After all was said & done, I could see myself fabbing one. It's just a glorified bracket.
  14. Shaggy
    Joined: Mar 6, 2003
    Posts: 5,207

    from Sultan, WA

    I'm going 60-62 chev p/u stuff in my T, easy to find stuff and cheap. best of all ansen, or tardel petal assy's take the dual MC's
  15. LIL.TIMMYUser Name
    Joined: Jan 30, 2009
    Posts: 741

    LIL.TIMMYUser Name

    x2 really likes the appearance as well. very easy to work with.

    Attached Files:

  16. On my '38 Ford pickup with 307 Chevy and T-5 trans from an S-10, I used a hydraulic clutch setup from a '70s Ford Courier (Mazda) pickup. I don't like internal slave cylinders because a) it's a pain to have to pull the trans to replace it, and b) if it goes bad, your clutch disc gets soaked with brake fluid. Slave cylinder on outside of bellhousing can be replaced and bled in under a half hour. I wanted hanging pedals in my truck (adapted a pedal assembly from a '55 Ford car). Just a matter of making the slave cylinder mount from scrap steel I already had, Basic Hot Roddding 101 type stuff. Mechanical clutch linkage (especially the bell crank) just takes up space that you don't have to spare on most older cars. If you're making a mechanical linkage from scratch, it's often hard to get the geometry right. With a hydraulic system, you can route the line however you need to in order to get it out of the way of exhaust system, etc. I have a bad arthritic left hip that doesn't work too well with a stiff clutch (of all the things I could have inherited from my father, did I get something useful like his photographic memory? Nooooo--I got the arthritic hip, arthritic left hip, just like Daddy) With the Mazda hydraulic setup, I can drive my truck all day without it making the hip pain worse.
  17. cooger
    Joined: Nov 5, 2008
    Posts: 233


    I just finished putting one on a T5 in a 55 two weeks ago.
    I fab'd the braket using the bottom two bolts on the drivers side of the bellhousing using an s-10 slave (pusher) into the stock arm. The master is a 3/4" Wilwood from Speedway, around $60 I believe. The slave is close the 3/4 bore of the master, its rated in mm-I converted it. Bottom line: its better that the manual stock linkage-which was hell since I used the s10 clutch-but its not really that easy to push down. I was surprised but I can live with it. Main thing is to be sure the bracket is super strong (mine is 3/8 plate) and the rod needs to be grade 8. The master is cool looking mounted on the firewall.
  18. fleetside66
    Joined: Nov 20, 2006
    Posts: 2,688


    Good point, Cooger. That one that bracket I had mentioned (above) was 3/8," with a Grade 8 rod. I was nice to have all of the perfect CNC'ed holes, I must admit. It was the only bracket on my build that I didn't make.

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