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Technical Hydraulic Clutch Question

Discussion in 'The Hokey Ass Message Board' started by thebevman, Jan 30, 2020.

  1. thebevman
    Joined: Dec 26, 2010
    Posts: 29

    thebevman
    Member

    Hello All,
    haven't posted on here for some time. I'm finally getting back into getting my '55 Dodge p/u going.

    My question, in short is, can a clutch's master cylinder be mounted below the level of the slave cylinder? My understanding is they can't, but I'm hoping there's a way.

    The backstory:
    I'm trying to see if its feasible to add a hyd clutch, under the floor next to the brake's master cylinder. The engine/tranny combo came out of a '64 w 200 (318A w/ NP435) that had a juice clutch and when my Grandfather swapped it in he used a 1/2" cable to operate the throw out fork, fork is on the passenger side. It probably worked well 40 yrs ago, but now it's almost scary. Years ago when I had more money than time I bought the master and slave cylinders then life, kids and such took priority.

    Thanks,

    Bev
     
    Last edited: Jan 30, 2020
  2. chicken
    Joined: Aug 15, 2004
    Posts: 164

    chicken
    Member
    from Kansas

    I don't see why not. It'll be a bit different to bleed, but should work fine once bled. I'd have a bleeder on the slave if at all possible,and maybe even have the slave loose and dropped below master level while bleeding it. Then just bolt in place. Really,though, it should bleed in place as well with some care and two people (or a vac or pressure bleeder).

    Terry
     
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  3. ekimneirbo
    Joined: Apr 29, 2017
    Posts: 1,848

    ekimneirbo
    Member
    from Brooks Ky

    I don't see why it won't work as long as it's a closed system. You might need to put a small reservoir somewhere slightly above the master cylinder and connected by a tube so you can add fluid without removing the top of the master cylinder.
     
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  4. thebevman
    Joined: Dec 26, 2010
    Posts: 29

    thebevman
    Member

    That’s for the info fellas. This has been eating me for a while, just plain stalled out on it. I can understand the difficulty I may have with bleeding, chasing bubbles and all.

    Would there be a problem with fluid back flowing onto the master’s reservoir?

    I do like the idea of have the reservoir up higher or at least the fluid level being higher than the slave cylinder.
     

  5. saltflats
    Joined: Aug 14, 2007
    Posts: 10,688

    saltflats
    Member
    from Missouri

    Put a check valve inline like one would use for a brake system.
     
  6. ekimneirbo
    Joined: Apr 29, 2017
    Posts: 1,848

    ekimneirbo
    Member
    from Brooks Ky

    You will have a master cylinder and a slave cylinder. The reservoir I'm talking about will feed the master cylinder and keep fluid at a higher level.
    If you go to a Pull a part and look for a manual trans S10 you can find nice little reservoirs that mount on the firewall. Probably a few bucks. You can see how GM did it. New ones on line aren't expensive. Make a temporary assembly in your vice/ workbench and get it working where it's easy to do. Then install it. Beats climbing under the vehicle over and over.
     
  7. Lloyd's paint & glass
    Joined: Nov 16, 2019
    Posts: 4,257

    Lloyd's paint & glass
    ALLIANCE MEMBER

    Did this on my last sedan, it worked great. No different that the brake master cylinder under the floor and below the wheel cylinders.
     
  8. thebevman
    Joined: Dec 26, 2010
    Posts: 29

    thebevman
    Member

    Damn! I should’ve asked years ago.

    Ekimneirbo, I know exactly what your talking about and that little S10 res wouldn’t be to difficult to mount out of the way. Bonus- I’m 2 mi away from my local pic-n-pull and have some return credits to burn.

    I’d thought about that too but found that check valve manufacturers explicitly advise against using their product in a hyd clutch system. If I recall they’re concern was the 1 lb- 2lbs pressure in the lines would keep pressure on the clutch. Probably mess with pedal feel too.

    Lloyd, thanks for letting me know that you’ve tested it out.
    Thanks again Fella’s looks like it’s a parts gathering weekend.
     
  9. KenC
    Joined: Sep 14, 2006
    Posts: 567

    KenC
    Member

    I happen to be working on a 60 Dodge hyd clutch setup this week. It is a 60 clutch housing in a 56 chassis, but with the later suspended pedal setup planned. The slave cylinder is always fully retracted, with no, (or at least very very little fluid in it), except when the pedal is depressed. So no fluid to flow back, except that in the line. Even if it had fluid, the cup would have to leak, admit air, in order for it to return to the res.
    My master will be elevated so the situation doesn't arise. but, I wouldn't worry even if it wasn't. But as another poster mentioned, a remote fill would be nice.
     
  10. Lloyd's paint & glass
    Joined: Nov 16, 2019
    Posts: 4,257

    Lloyd's paint & glass
    ALLIANCE MEMBER

    Kind of ashamed to admit it, but i bought one of the CNC setups with the pedal assembly and pull type slave cylinder all in one kit. Cheap. Best i remember the slave cylinder had a 1" bore. Fabricated a bracket on the inside of the frame for the slave. But my engine and transmission were mounted solid.
     
  11. ekimneirbo
    Joined: Apr 29, 2017
    Posts: 1,848

    ekimneirbo
    Member
    from Brooks Ky

    The thing to remember is that the master cylinder and the slave cylinder have to be matched to work properly. Don't know if you are using a slave that mounts outside the bellhousing and pushes a fork.......or one of the newer slaves that mount around the input shaft inside the bellhousing. If you buy a master and slave that fit a certain OEM vehicle, you can figure they are matched to work with each other. If you go aftermarket you need to research what you buy. If you get a larger master cylinder, you can always limit travel so you don't over travel the linkage. The ones that mount inside the housing are more expensive and harder to change. You might order a "Day Motorsports" catalog. Lotta Hambers might find this catalog helpful for lots of other things too.
    Day Motorsports 1 001.jpg

    Day Motorsports 2 001.jpg

    Day Motorsports 3 001.jpg

    Day Motorsports 4 001.jpg
     
  12. thebevman
    Joined: Dec 26, 2010
    Posts: 29

    thebevman
    Member

    I've been looking at different master's and such online but since I already have the "stock" master and slave cylinders I'm going to try to use them... Although, I might need to get creative with the cap on the master... but we'll see.
     

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