sloppy Z bar linkage.....probably pilot error

Manual Transmission & Clutch Discussions

  1. clementine

    clementine Flight risk FABO Gold Member

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    Hey FABO!
    Doing a shake down on a friends new 67 Dart and smoked the clutch pretty good. Dual disc Mcleod (diaphram) and quick time scatter, A833 and Z bar. It seems like not enough travel in Z bar and it hits the starter when the clutch is fully engaged although I believe it prevents full engagement. Right now my goals are to make the pedal come all the way up and get engage/disengage in the middle of throw of the pedal vs at the bottom where it is now. The linkage that goes through the fire wall and the bottom of the Z bar to push rod has mucho slop on both ends due to the holes being slotted. Are there bushings on the ends? Should there be this much play in the system? I feel like grinding the starter on the corner it hits on a little bit/ tightening up that slop with rod ends for adjustment and possibly playing with the pivot of clutch fork along with a longer throwout bearing are my solutions to consider.....

    What do you think?
     
  2. AJ/FormS

    AJ/FormS 68 B'cuda fb, Form S clone ... 367/A833/3.55s FABO Gold Member

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    The peddle assembly comes in two ratios; one for slantys and one for everything else.
    The TO-fork in the window, should be almost all the way towards the rad with foot off the clutch, and, going to the rear, should have some room for adjustment as the friction material wears off.
    The fork should be about 10.875 long, and for an A-body, almost dead-straight.
    Adjustment is with the pivot bracket.
    The Z-bar has nylon bushings, that ride on balls, that are attached to the end-brackets, one of which is bolted to the bellhouse and the frame-end ball-bracket should be welded and reinforced.
    The Z-bar has to be positively located so it cannot move laterally. It should be parallel to the ground and at about 90* to the centerline of the car.
     
    Last edited: Sep 19, 2019
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    • clementine

      clementine Flight risk FABO Gold Member

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      1568936566325724478374.jpg
      Thank you for quick reply sensei....

      Sorry....
      "the rad"?
      Which end of the TO fork is towards the radiator? I think the "push" side vs the bearing side should be closer to radiator with foot off clutch. Ya?

      I see the nylon bushings for the Z bar tube. The linkage has these long.......hold on ill send a picture.....

      This is the push rod from bottom of Z Barr but similar play in two spots on both ends of the rod through for wall off pedal.
       
      Last edited: Sep 19, 2019
    • clementine

      clementine Flight risk FABO Gold Member

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      It adds up to at least 1" Of end play... necessary?
       
    • MOPAROFFICIAL

      MOPAROFFICIAL Well-Known Member

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      Yes there are nylon bushings in the z bar.
       
    • toolmanmike

      toolmanmike FABO Staff Staff Member FABO Gold Member

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      I adjust the throw out bearing 1/8"-3/16" away from the pressure plate fingers. Make sure the bushings are good and in place. The holes in the linkage are not supposed to be round. There is supposed to be slack in each one. All the slack added together gives you the free play.
       
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      • clementine

        clementine Flight risk FABO Gold Member

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        Im supposed to remove the return spring on the pedal when using a diaphram clutch .....right?
         
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        • SSG_Karg

          SSG_Karg Hillbilly Hellraiser

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          Correct
           
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          • clementine

            clementine Flight risk FABO Gold Member

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            Danka...
             
          • dano

            dano Evil Handy Man

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            You mention a scatter shield, it is designed for the 71-down ball pivot or the 72-up? They both bolt to the bell but one correctly places the z-bar inline with the ball stud on the frame. If wrong the z-bar will be canted at an angle. This would make for some functional issues. I only mention it because my aluminum TKO bell was designed for the 72- up.
             
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            • clementine

              clementine Flight risk FABO Gold Member

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              Good info..

              Thank you.
              Investigating
               
            • AJ/FormS

              AJ/FormS 68 B'cuda fb, Form S clone ... 367/A833/3.55s FABO Gold Member

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              Should read;
              The TO-fork,
              in the window,
              should be almost all the way towards the rad-side ( the front side,or clutch side,or left if viewing it from the driver's side of the car)
              of the window,
              as opposed to the transmission side, or rear bumper side,
              with foot off the clutch.
              As for the long slots, they have to be there to get over the pins, and the linkage is engineered to work with them, they'll be fine.

              If you get this right, it should all work out right.
               
              Last edited: Sep 19, 2019
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              • mopardude318

                mopardude318 Well-Known Member

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                You make a good point... I have a new QuickTime scattershield, and when I hook up the linkage that is proper for ‘71 and down, it’s not quite perfectly in line... I wonder if the ‘72-up ballstud would line up better... I should call QuickTime and ask what they designed the bell to use...
                 
              • AJ/FormS

                AJ/FormS 68 B'cuda fb, Form S clone ... 367/A833/3.55s FABO Gold Member

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                No you can't swap one for the other if you are already close, cuz the wrong one will be waaaay outta line, hence what I said; parallel to the road and at about 90* to the centerline of the car.
                Furthermore the wrong one will not bolt on; the holes are in the wrong place. If your Z-bar does not fall in at parallel to the road and at about 90* to the centerline of the car, because the BH end is in the wrong place, then the BH will also have to be changed.
                I guess you could move the frame-end ball, to get the Z-bar to be parallel to the road and at about 90* to the centerline of the car, but then you would have to re-engineer the downrod, as it may no longer operate in the firewall window, as it was designed to.
                Alternatively, you could re-engineer the Z-bar lever lengths and angles to work in it's new location. Which with the diaphragm clutch,and the removal of the overcenter spring, is doable.............. right up until you install the headers and everything wants to occupy the same real-estate.
                Happy HotRodding
                 
                Last edited: Sep 20, 2019
              • clementine

                clementine Flight risk FABO Gold Member

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                This car is close. The fork is parallel, it is about 90* to centerline. It's just that it starts to engage right off the floor and it is 1.5" below the height of the brake pedal. If I took out the slop and put a throw out bearing that is 1/8"+- from diaphragm, it would put engagement towards the top of the throw of pedal and put the pedal higher.

                I think i can meet all of A/Js criteria of fork positioning, but the slop seems to be screwing with my pedal height and engage/disengage height.

                I'll keep you updated to the progress...or lack there of.

                Thanks for the input!
                 
              • AJ/FormS

                AJ/FormS 68 B'cuda fb, Form S clone ... 367/A833/3.55s FABO Gold Member

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                the slop is NOT the problem! and you can't do anything about it anyway, cuz the only way to get those ends over the pins is if the sloppy holes are there. That slop is on the backside of the hole where it doesn't matter if it's there.
                The clutch pedal always sits lower than the brake pedal, mind you not usually 1.5 inches but more like half of that.
                Also, on the factory system;
                you never have to push the clutch all the way to the floor to get the departure required. With the freeplay properly set, departure usually comes about half-way to the floor.

                Are you sure your pedal set is from a V8 car. The V8 pedal when parked, will pull the downrod up higher, which pulls the TO fork closer to the engine side of the window, which pulls the TO bearing further off the fingers. Then when you readjust the freeplay, the V8 pedal has more available travel, and gets things moving sooner.

                Parallelism refers to the Z-bar... not the fork!
                 
                Last edited: Sep 20, 2019
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                • clementine

                  clementine Flight risk FABO Gold Member

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                  Thank you !
                   
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