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  • Flightomatic problem

    I have been working some bugs out of my transmission that I recently rebuilt. the problem seems to be that as the trans heats up low and reverse start to slip. Reverse is worse than low. I have adjusted the rear band over and over and it works for a while then reverse and low start to go away again. My rebuild was new clutches and seals. Everything seemed to be OK when I put it together. This was my first attempt at an auto tranny, so I could have missed something. Any ideas? On another note the rebuilt 289 4barrell R2+ cam engine runs AWESOME.
    1962 Champ

    51 Commander 4 door

  • #2
    Kurt,

    What was the operating condition and/or problems before you installed the new clutches and seals?

    Some thoughts on the low/reverse problem...

    The rear band is the most obvious common item, as it is applied in first and reverse only. I assume that the friction surface on the rear band was OK when you assembled the transmission. The grooves in the friction material should still be visible. If the friction surface is too worn, the ends of the band can contact each other preventing the band from closing tighter. Could the little strut between the servo and the band possibly be in backwards?

    Adjustment of the rear band is fairly simple (even without a J-5883 tool). Snug it up and then back off 1-1/2 turn. Make sure that the lock nut is tight after the adjustment.

    If the band is still slipping, I would suggest that the rear servo isn't applying sufficient force. This could be due to low fluid pressure, or leakage around the piston seals in the servo. Also, fluid pressure could be leaking if the bolts that hold the servo to the case are slightly loose. Note that the two bolts that hold the servo in place are slightly different. The bolt with the pointed end goes into the center support of the transmission. If the bolts are reversed, it may prevent the servo from being drawn up tight.

    Similarly, if the control valve is not tightly seated to the case, fluid pressure can be leaking. Fortunately, much of this can be checked without removing the transmission. Dropping the pan and removing control valve assembly will allow an air pressure leak check of the rear servo circuit. This is described in the shop manual.

    Hope that this helps. Please let us know what the problem turns out to be.

    Jim Bradley
    Lewistown PA
    '64 Daytona HT "Rerun"
    Jim Bradley
    Lake Monticello, VA
    '78 Avanti II
    sigpic

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    • #3
      The transmission was in a non running parts car, so I have no idea if it worked or not before hand. Is it possible to get the rear band too tight and break something? The reason i ask is I have been carefull adjusting this and maybe I have not been getting it tight enough before backing it off. When I adjust the band it works great for a short time then goes back to slipping. The band was in good shape when I installed it and I am sure I got the strut back in correctly.
      1962 Champ

      51 Commander 4 door

      Comment


      • #4
        Front band is torqued in inch pounds / rear band is foot pounds

        Bob Johnstone

        http://www.studebaker-info.org
        55 President State Sedan
        64 GT Hawk
        70 Avanti (R3)
        64 GT Hawk (K7)
        1970 Avanti (R3)

        Comment


        • #5
          Not knowing what sort of problems the transmission had before you started adds to the adventure!

          I doubt that you could break anything by over-tightening the rear band adjustment. The rear servo has a fairly long throw, so even if the adjustment were a little loose I would not expect it to slip. If the adjustment were too tight and the band was dragging, it could overheat and slip. However, I would expect that a dragging rear band would cause other strange symptoms in other gears.

          It sounds like your problem is heat related. There will be some viscosity change in the fluid as it heats up, but it shouldn't be enough to make a change in operation unless there is something very marginal.

          The next link in the chain is the rear servo. Did you install a new piston seal? Did you clean the control valve and pressure regulator assemblies?

          Have you done a fluid pressure test? By attaching a pressure gauge to the transmission at the pipe plug behind the linkage, you can determine whether there is leakage in the Low and/or Reverse circuits. Do you have a shop manual? This procedure is detailed under the "Diagnosis Checks" section.



          Jim Bradley
          Lewistown PA
          '64 Daytona HT "Rerun"
          Jim Bradley
          Lake Monticello, VA
          '78 Avanti II
          sigpic

          Comment


          • #6
            When you say it worked okay for a short time, are you talking about the length of time it takes for the fluid to get hot? Also, when you readjust the reverse band, how many turns are you going each time you do that? Are you finding band material in the pan and filter? Now, if it only works until it warms up, there's a ring or seal problem. You may have nicked a servo seal when you assembled it. One more thing; just to make sure--does high gear work okay after it warms up?

            Comment


            • #7
              Thanks guys for the input. Today I checked pressures and they were good in all ranges. No matter how tight I make the band it still slips. It will engage low, pull hard then start to slip. Reverse engages but if you give it too much to fast it will slip. Also today it did not seem to matter if it was cold or hot, same problem. So the problem has Changed slightly Drive range works perfectly, engages strong shifts smoth and holds 2nd and high with no slipping. I guess I will pull the pan and see what is wrong. I reused the old band because it looked like new. I hope it's the servo, or something related. Not looking forward to pulling the tranny to replace a band. On a happier note the 289 is running better all of the time. Big difference from the 6cyl 3spd that was in it's place
              1962 Champ

              51 Commander 4 door

              Comment


              • #8
                I thought everything went out the back on that trans, so you could replace the band with it in the car. Also, there is a replacement band called a "Snap-Band", I've installed in C4's and C6's with just dropping the valve body. But I don't know if they make one for your application.

                Comment


                • #9
                  The "snap bands" were only for the front band replacement. The band may look good but the area showing the wear will be at the parting line or where the band ends. There may be grooves in the lining surface they should be uniform depth all the way around,if they are shallower at the ends the band should be replaced. Lou Cote [8D]

                  Comment


                  • #10
                    While you've got the pan down, check the operating lever on the servo for a crack beginning inside the radius of that curved lever. Its a cast piece that will partially crack, thus applying less pressure to the band.

                    Why do I know?

                    I once pulled a slipping trans and just swapped in a rebuilt spare, without looking inside the old one. Several years later when I went to rebuild the old one, all I found wrong was the crack I've described. Once removed it easily broke in my hand.

                    Good luck!

                    Stude Intertnational should still have them.

                    Comment


                    • #11
                      skyway,

                      The failure of the servo operating arm that you describe would certainly be consistent with the problem that Kurt describes. I've not seen that before, but it really makes sense. I suppose that it could be a fatigue issue or, more likely, caused by someone over-tightening the servo adjustment at some point in the history of the transmission.

                      Kurt,

                      Please let us know what you find.

                      Jim Bradley
                      Lewistown PA
                      '64 Daytona HT "Rerun"
                      Jim Bradley
                      Lake Monticello, VA
                      '78 Avanti II
                      sigpic

                      Comment


                      • #12
                        MMMMMM,

                        Well my champ 7e7 has basically the same issue....My engine temps get very hot- almost redline and the tranny will not Shift down back into first(like when you approach stop signs)-the transmittion goes into free wheel---Then if i rev up the engine the tranny will "grab" studder and I am off. The Overheating issue i believe is a clogged block - but not sure. The champ will idle all day at normal temps-Then when its driven a couple of miles the temps go up. Back to the tranny.If i would approach my stops slowly the tranny will shift down most of time-and work fine. During the "free wheel/Nuteral" mode I can manually place the truck in reverse - but the only why to get it back into First is revving engine(which is really hot anyway-close to redline)

                        Comment


                        • #13
                          Thanks again guys for the input. I have not pulled the pan yet to see what is going on. I work in Ag Retail, so very busy because of planting season. When I tear into it I will let you all know what is wrong.
                          1962 Champ

                          51 Commander 4 door

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