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Folks Of Interest Any Advice on a broken Merc-o-Matic

Discussion in 'The Hokey Ass Message Board' started by Mitch Perry, Apr 29, 2021.

  1. Mitch Perry
    Joined: Apr 29, 2021
    Posts: 4

    Mitch Perry

    Hi all, long time reader, first time writing...

    I’ve run into an issue with the Merc-o-Matic in my ’52 Mercury. Last fall, the transmission stopped shifting, and would occasionally slip while in reverse. Over the winter, I dropped it out and took it apart to try and identify the issue. I found lots of dirt and brass shards, so I cleaned everything very well and replaced all the seals, bands, clutches, and steels. No hard parts appeared to be broken or worn, and when it was reinstalled, reverse works great but still nothing shifts automatically. Does anyone have any idea what I may be missing?
     
  2. adjust the kick down rod on the carb linkage
     
    Nailhead Jason likes this.
  3. Make sure that your band is adjusted properly. It’s been a while but I seem to remember an external adjustment on the case accessed through the trans cover in the floor.
     
  4. Marty Vanin
    Joined: Feb 22, 2017
    Posts: 74

    Marty Vanin
    Member

    Like hudsonmand said,adjust the kd rod first. Did you disassemble the valve body and governor and clean all the trash out of the bores? You can get to the governor by removing the plate on the side of the tail housing,rotate the driveshaft and watch the valve, it should move in and out of the bore easily.If it doesn’t,remove the 2 screws and remove the section with the valve in it ,take it apart and clean it,and go from there.
     

  5. Mitch Perry
    Joined: Apr 29, 2021
    Posts: 4

    Mitch Perry

    Thank you all for you advice. I’ll take a closer look at the kick down rod tomorrow and see if it’s adjusted properly. When I had it apart, I cleaned the valve body and governor, so I should be good there. I put the bands back in to the specs that came with the kit, and they seem to be engaging well.
     
  6. Good on you for trying to fix/rebuild a 65 yr old trannie and not just throwing in the towel !
     
  7. jaracer
    Joined: Oct 4, 2008
    Posts: 1,476

    jaracer
    Member

    The Merc-O-Matic times shifts by balancing throttle pressure against governor pressure. Throttle pressure is controlled by the rod from the carburetor linkage down to the transmission. The first thing to do is to make sure the linkage is adjusted properly.

    If you have reverse, manual low, and second gear, then all your clutches are working properly. In manual low you use the forward clutch and the low/reverse band. In second, you use the forward clutch and the intermediate band. In reverse you use the high/reverse clutch and the low/reverse band. In high gear, the one you aren't able to obtain, you use the forward clutch and the high/reverse clutch. That covers all the bands and clutches. You either have too much throttle pressure because of a linkage problem or you have no governor pressure. I'll take a look, but I don't believe I have a manual that outlines throttle linkage adjustment on a 52 model, but I may.
     
  8. jimmy six
    Joined: Mar 21, 2006
    Posts: 10,998

    jimmy six
    ALLIANCE MEMBER

    If your close to SoCal I’d give you an air cooled one out of my 56. The flathead bell and torque converter is needed and my tail housing is off since I used on the cruise-o with modifications. Worked perfect with 9000 miles on it . I wanted a true3- speed.
     
  9. jaracer
    Joined: Oct 4, 2008
    Posts: 1,476

    jaracer
    Member

    I did find the adjustment procedure. There are two adjustable rods in the throttle valve linkage. The adjustable rod between the carburetor and the bell crank (they call it the z-bar) requires a special tool and my book has an extremely poor picture of using it. If you haven't played with the length of this rod you can just adjust the lower rod. The carburetor need to be at low idle setting (you don't need the engine running). The adjustment is on the upper clevis on the rod. The manual says to pull the pin from the clevis and pull up on the rod so that the linkage inside the trans is at the low pressure stop. While holding up on the rod, loosen the jamb nut and adjust the clevis so that the pin will just slide the hole on the bell crank (carb at low idle). Now turn the clevis 2 1/2 turns counter clockwise (lengthening the rod). Put the pin back in and you should be good to go.

    That's actually the same adjustment called for on my 57 Ford-O-Matic. However, the special tool required to set the upper rod on my 57 is a 1/4 in drill bit.
     
  10. jaracer
    Joined: Oct 4, 2008
    Posts: 1,476

    jaracer
    Member

    If throttle linkage adjustment doesn't help, then you problem is probably in the governor. On that transmission the governor is fed by the rear pump in the transmission. If it isn't being driven or able to get fluid, the transmission won't shift.
     
  11. I run a Ford-0-Matic in my Model A and rebuilt the trans before installing it. I found some different opinions on adjusting one of the bands. There is a Ford Transmission website that helped a lot I'll tr to find the site and post back...
     
  12. Mitch Perry
    Joined: Apr 29, 2021
    Posts: 4

    Mitch Perry

    Thanks jaracer, I've adjusted the throttle value linkage to spec, and unfortunately it still didn't work. For good measure, I tried 9 other adjustments, just in case i bent the rod during the re-installation. I'll have to take another look at the governor to see if everything's okay. When I was rebuilding the trans, I gave it a good cleaning and made sure I reinstalled it properly. Not shifting into 3rd was what prompted me to rebuild it in the first place, so the problem is likely something I didn't see.
     
  13. jaracer
    Joined: Oct 4, 2008
    Posts: 1,476

    jaracer
    Member

    The fact that it moves in reverse means the clutch you need to apply to achieve high gear is working. I suppose the throttle valve could be stuck at high pressure, that would delay the shift to the maximum shift point. Have you tried winding it out in drive to about 50 mph? If it won't shift at max speed, it is probably a problem with the governor.

    You can check the throttle valve with a pressure gauge. In D or L the pressure should be 52-67 psi at idle. It should go up to 137-157 at stall (pedal to the floor, brakes applied). That would prove that the throttle valve is working as it should. In R the pressure should be 52-67 at idle, and 184-204 at stall. That would prove the high clutch is okay hydraulically.

    There is no pressure check for the governor since the only port on the transmission is for mainline pressure. However. there is an air test. You have to drain the fluid, drop the pan and the control valve body. Remove the governor inspection cover so you can see the governor valve. If you apply shop air to the front clutch passage in the case you should hear a click and see the governor valve move. I'll post a picture shortly.
     
  14. jaracer
    Joined: Oct 4, 2008
    Posts: 1,476

    jaracer
    Member

    Here's the test out of an old M-E-L Transmission Maintenance Manual.
    governor test.jpg
     
    Budget36 and ottoman like this.
  15. jaracer
    Joined: Oct 4, 2008
    Posts: 1,476

    jaracer
    Member

    Also, I was wrong about the governor only being supplied by the rear pump. In your transmission it can be fed by either the front or rear pump. Losing the rear pump won't cause the governor to be inoperative.
     
  16. Mitch Perry
    Joined: Apr 29, 2021
    Posts: 4

    Mitch Perry

    I removed and checked the governor, it was clean and behaving as it should. Then I dropped the pan and the main valve body. I put compressed air in all the passages, and everything worked as it was supposed to. While I had the valve body in my hand, I noticed that the throttle valve was behind the plate rather than riding along it, which was preventing it from moving with the governor pressure. I fixed that issue, but noticed that my valve body was missing an 'S' shaped spring that sits at the end of that valve on the outside of the valve body. I put it all back together anyway, and it's now shifting into 3rd, albeit a bit hard.
     

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