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84 Cj7 Hydraulic Clutch Slave

Discussion in 'Intermediate CJ-5 and CJ-6 Tech' started by John A. Shows, Nov 26, 2018.

  1. Nov 26, 2018
    John A. Shows

    John A. Shows Comic Relief Sponsor

    Mendenhall...
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    Guys, I think I've posted this question 3 or 4 times over the past 3 or 4 years and I'm such a stinking lazy bum I never follow through with the repairs.

    I'm sorry but I'm reposting it in hopes that someone might be able to help diagnose my issue.

    Basically, my hydraulic clutch slave cylinder is over extending and blowing out. It'll work fine for a while and then for no apparent reason at no particular time the piston inside the cylinder just pushes too far and comes out. Of course when this happens the fluid just pours out and the piston gets stuck "outside" the slave and my clutch is engaged and I have nothing. I have to climb under the jeep and use a pry bar to move the clutch fork and tap on the side of the piston to line it back up with the cylinder so that it will go back in.

    Then I can start the jeep in neutral and do my shifting with no clutch to limp on home. Then the jeep sits in my garage for a year until I decide to swap it out again.

    This is an 84 cj7 with an NV45 transmission and an Advance Adapter's bellhousing mated to an inline 6 cylinder.

    The slave cylinder itself is just a stock slave cylinder and I'm almost positive that the master cylinder is also a stock master cylinder.
     
  2. Nov 26, 2018
    tarry99

    tarry99 Member Sponsor

    Northern California
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    I thought you talked with Novak about this?.......This has been going on a long time.............This is probably all about having the wrong Bore size in the master vs the bore in the slave. If the bore in the master is much larger than the slave bore........upon full travel the fluid / volume created by the larger bore will blow out the smaller cylinder........

    Why don't you take out the slave cylinder and measure the bore and travel of the piston? And if you can see if the bore is marked on the master cylinder housing or perhaps a part number. Knowing what you have makes it easier to apply a fix...........

    But knowing the travel in most OEM slave cylinders are no more than 1.250-1.500" at best , I think you need a longer travel Slave cylinder.........and that is where Novak comes in as they build a Billet slave that has about 2" of travel....plenty of info here: Hydraulic Clutch Slave Retrofit Kit for Chevrolet Bellhousings

    Get the info on both parts if you can.........
     
  3. Nov 26, 2018
    John A. Shows

    John A. Shows Comic Relief Sponsor

    Mendenhall...
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    Thanks Tarry...yes, this has been going on for a long time. I actually did buy the Novak slave and it sat on my dining table for a few months and I tried to install it this past Saturday. Turns out Novak's kit won't fit because my bellhousing is an Advance Adapters bellhousing and Novak doesn't have a bracket that works with AA's Bellhousing.

    I called AA and they just use the stock slave cylinder.

    I have no idea of the bore size of the master cylinder I'm using, but I've assumed it's also just a stock master cylinder.

    I will measure the bore of the slave tonight and will check the master and see if there's a bore size listed on it, or perhaps a part number.

    I would think however that if the bore wasn't matched between the two that the blow out would occur immediately rather than after driving it for a while.
     
  4. Nov 26, 2018
    Chilly

    Chilly Active Member

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    Is there a way to limit the clutch pedal travel? It's a displaced volume problem: you are moving more volume from the master than the slave can handle. Volume from the primary is:

    (Primary Bore Dia) x 3.14 x Stroke

    Could stick with current master cylinder but limit the stroke. You may be able to limit the stroke at the bottom, or at the top. I don't think it will matter, effect should be the same I think.

    Chilly
     
  5. Nov 26, 2018
    John A. Shows

    John A. Shows Comic Relief Sponsor

    Mendenhall...
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    Tarry, I looked up the stock slave cylinder that i'm using and the slave itself is listed as .88" which is 7/8". Now if I can verify what Master Cylinder I'm using maybe that will help.
     
  6. Nov 26, 2018
    John A. Shows

    John A. Shows Comic Relief Sponsor

    Mendenhall...
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    Tarry, I searched for replacement clutch slave cylinders for my jeep and they have all of them listed as 13/16" master cylinders. I guess you also have to know the throw length too but I'm not sure how to obtain that without removing it and just measuring it.
     
  7. Nov 26, 2018
    John A. Shows

    John A. Shows Comic Relief Sponsor

    Mendenhall...
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    correction...the master cylinder is 13/16"...not the slave cylinder.
     
  8. Nov 26, 2018
    Chilly

    Chilly Active Member

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    Seriously, easy solution is to limit stroke. I don't have a hydraulic master swinging assembly in front of me but the manual swinging assembly from my 73 has a tab that limits the back-stroke. Does yours? Seems like it should if it doesn't. Can you post a photo of your pedals at rest? Maybe a photo shot up under the dash if you can view whatever limits the travel?

    On the manual setup travel is limited by the floor, at least on mine. Stop-gap solution could be as simple as screwing a body mount puck to the bottom of your pedal if it's hitting the floor. But there is my way, and the right way, so I will not be offended if you keep looking for solutions.
     
  9. Nov 26, 2018
    John A. Shows

    John A. Shows Comic Relief Sponsor

    Mendenhall...
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    I'm considering doing just that chilly. Not offended at all.
     
  10. Nov 26, 2018
    Chilly

    Chilly Active Member

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    Before limiting travel do some messing around to see how much pedal you need to release the clutch fully with a little extra margin. You sure don't want to limit travel to where you aren't fully released. If the slave was made properly, and is properly installed, it should be fine.

    If you find it takes up a fair amount of the travel to release the clutch you can still limit down-travel but lengthen your slave pushrod (or move slave closer to the paddle) so it releases mid-stroke or so.

    Wish I was closer, seems like an interesting problem. I'm pretty good at holding a cold drink in my left hand while I offer advice based on the smallest amount of consideration. It's my special sparkle.
     
  11. Nov 26, 2018
    John A. Shows

    John A. Shows Comic Relief Sponsor

    Mendenhall...
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    I'm almost positive everything I have is factory stuff. A 13/16" master cylinder bore and a 7/8" slave cylinder bore. Regarding the pedal travel, the pedal doesn't need to travel far at all to engage the clutch. I'm totally confused on why this will work for a while and then just pop out. It's like the travel of the piston in the slave gets longer over a period of time.

    Will a leak in the line somehow cause this? I'm asking because I think I have a slight leak somewhere. I don't see any fluid on the line, but I've noticed a loss of fluid in the master cylinder.

    I think I'm going to buy both a new MC and a new SC together as well as a new fluid line. If everything is new and everything is stock, it just seems like everything should work as it should. I have replaced the slave a dozen times but I've never replaced that master cylinder. Maybe the wrong MC has been on it since I bought the jeep some 15 years ago.
     
  12. Nov 26, 2018
    Chilly

    Chilly Active Member

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    If stock parts then probably an inexpensive proposal to change the master. Since the problem persists despite changing the slave it's probably not the slave, though if it's popped out a few times maybe it needs to be replaced.

    If mine I'd try a new master and see what happens. If that doesn't solve it don't give up! We'll fix this! Certainly don't let your Jeep sit because of this problem. I think you are going to fix this very soon.
     
  13. Nov 26, 2018
    John A. Shows

    John A. Shows Comic Relief Sponsor

    Mendenhall...
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    That's what I'm gonna do Chilly.

    And hopefully I won't be here next year posting yet again about my dang hydraulic clutch problems.
     
  14. Nov 26, 2018
    John A. Shows

    John A. Shows Comic Relief Sponsor

    Mendenhall...
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    I've heard or read in a couple other places of people mounting the slave on the opposite side of the bellhousing but I can't for the life of me see how that changes anything. Certainly wouldn't change the length of movement of the push rod or piston inside the slave.
     
  15. Nov 26, 2018
    tarry99

    tarry99 Member Sponsor

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    Before you take it apart........see how much travel you have and see if your anywhere near the stops.........and see if you can get the clutch to release with whatever travel that is including some free play................and a 13/16" MC vs a 14/16" or 7/8" slave is normally the opposite way you would normally run those............as a smaller bore slave like a 3/4" will increase the travel.

    Travel at the slave side is always and issue because of the ratio change on the throwout fork that cut's the overall travel inside the bellhousing by 50% ...........I'll send you a PM
     
  16. Nov 26, 2018
    Framer Mike P

    Framer Mike P Member

    Hopkinton, NH
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    It was the 4 cylinder cj7s that came stock with the hydraulic clutch linkage. My father and I used these parts to covert our cj5 30 some years ago. I recall there was a white plastic cone that slipped over the end of the slave cylinder push rod and pushed against the clutch release arm. Is there any chance this piece is missing and the slave is over extending to compensate?
     
  17. Nov 26, 2018
    Framer Mike P

    Framer Mike P Member

    Hopkinton, NH
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    4wd.com lists the part I am refering to as the clutch slave cylinder pivot. Omix-ADA 16919.23 $1.99
     
  18. Nov 26, 2018
    RATTYFLATTY

    RATTYFLATTY I think you need a little more throttle

    Central MN
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    Have you checked to see if the slave is retracting all the way back in the bore? You might have a return action that is not completing the stroke, think 2 steps forward and 1 step back then repeat. Can you get it to pop out by cycling the pedal numerous times with a 10 sec pause between cycles? How close is the exhaust, Heat issue? I run the same stock setup in my 5 on a T18 with about 1.5" added to the clutch fork to get it to line up. Been working great for years. We must not be seeing something simple with yours.
     
  19. Nov 27, 2018
    Norcal69

    Norcal69 Member

    Cottonwood, Ca
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    What year is the NV4500 from? GM or Dodge?
    Both Dodge and GM factory hydraulic clutch setups work great. It would be pretty simple to adapt a factory setup. The Later GM style with internal hydraulic release bearing works flawless. It may be possible to put the later gm bearing retainer on your trans and use the hydraulic bearing.
     
  20. Nov 27, 2018
    John A. Shows

    John A. Shows Comic Relief Sponsor

    Mendenhall...
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    I have no idea what year the transmission is but the guy who built the jeep bout it from Advance Adapters in 2000 along with the Atlas T-Case. I spoke with them yesterday and gave them the number from the T-Case. All they told me was that it was a Dodge and was bought in 2000.
     

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