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Discussion Starter · #1 ·
Hello,
I have a 1996 and 1998 Taurus that share a similar transmission problem. The 1996 is much worse. Here is the details. I just went through the trans and all seems well except one problem still lingers. If you start at a standing start and Let it go through the gears all is smooth as can be. Part throttle, full throttle all is good. The problem I have is with the low speed 2-1 downshift. If it is a coast down downshift it has a rather harsh downshift followed by a slight surge. (I think I feel it disengage 2nd and that is the first clunk followed by a re-engagment that is the surge) In a forced 2-1 downshift things get much worse. If you are going 15 or so and oush the accelerator down to force a 2-1 downshift the engine will flare momentarily (like the trans was in neutral for a fraction of a second) Then the trans will shift in to low gear while the RPM's are high. I would compare it to having a standard trans and put in the clutch, rev the motor then pop the clutch. I call that engine flare. Both of my Taurus's do that but the AX4S is every time it does a forced 2-1 downshift.

It had this problem before I took it apart and replaced all the clutches etc. The trans had an intermediate clutch failure probably caused by the engine flare so if I don't get it fixed I am going to be doing it yet another time. No Fun. I have to believe that if my 1996 and 1998 both do it there has to be a common failure that causes this but I'm not sure. I downloaded the reapir manual from this site and it was helpful with the repair but not much about this particular problem. Any help or comments would be greatly appreciated. I am a diesel mechanic and have no experience with this trans though I have done several Allison automatic transmissions for heavy trucks.
Thanks in advance...:D
 

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It's the transmission design. They don't like 1st gear, 1-2 upshifts are normally unpleasant, and the only time they like to go back down into 1st is if you're fully stopped. If you're still moving, it's 2nd for you. If you force the downshift, your TC will lock (from what I can feel) and your RPMs will rise to the speed your vehicle is moving, then decelerate. If your problem is exaggerated, you might consider a shift kit in the valve body, but our transmissions aren't the pinnacle of design and technology.
 

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Discussion Starter · #3 ·
Thank you for your comments. My thoughts are this. It used to work better. What has changed (Worn?) that is causing the exagerated problem? The root cause, if you will. It seems to be associated to the boost valve sleeve from what I can find on the net. Before I do any more I am hoping that there is a person who has been through this and can say "X" is the problem. Here is why and this is the fix. I really don't want to do it again and again. I'm sure we have both done that. :(

Oh, and believe it or not the 1-2 upshift is fine. It is the 2-1 coastdown or worse yet forced (by far) downshift that hurts.
 

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Discussion Starter · #4 ·
Maybe I mispoke. What I meant by a forced down shift was like after a corner and sppeds are down to 15 or so. I roll gently in to the throttle and the trans downshifts, the engine flares and the trans locks in with a big clunk. I am not moving the lever at all. I call it forced downshift because I accelerated and "forced" the downshift. It is a normal action for the trans so maybe I used the wrong term. Thanks for your comments. :rolleyes2:
 

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Discussion Starter · #6 ·
After more checking online I disccovered that Ford had a problem with shift solenoids that did no deactivate mechanically. The valve portion of the valve could "hang" and cause a very long downshift because it was so slow to return to the off position. (mechanically not electrically. The spool hangs). Has anyone experienced this and fixed one?
 

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I have/had this problem on my 94 AXODE tranny. I fixed it 12 years ago with a half can dose of SeaFoam Trans Tune, drove it until it stopped acting out, (about a week), then did the pan drop, filter change & full tranny fluid pumpout with the specified Motorcraft Mercon fluid. This lasted about 4 years, then the 2-1 hanging downshift began again, so it got another half can dose of Trans Tune & another pan drop, filter change & full fluid pumpout & that fixed it again.
Last year it began acting out again & the Trans Tune didn't fix it, so I tried 5oz of Auto-Rx & am still in the process of running it, but so far just a little success. It's better but not completely ok. It's down shift has always hung up more often on right turn down shifts for some reason, it's still that way.

SO, thats what I've done over the past 10 years, the results I've had & where I persently am on my current 2-1 hanging up down shift.

I've always done the full tranny fluid pumpout every 25-30K miles, the fluid has always looked ok, filter too, very little paste on the pan magnet, very very light dusting of pan deposits, never any pieces of anything in the pan or in the filter, the tranny looks very clean inside, no deposits of any kind visable, so it seems at least for my 2-1 down shift problem, it must be some slight sludge, gum, varnish, ect problem that shows up every 3-4 years or so & that the Trans Tune can dissolve, put into suspension for the tranny filter to take out. That is until this last time, now it sorta seems it may be more than deposits, as it's taking longer to get noticeable results. I've heard our tranny is mighty sensitive to debris, so I've considered adding an inline filter, like a Magnefine, or the like, to the tranny return line, but maybe it's too late for me, I don't know.

A long story, but maybe some things you'll recognize & other thoughts for consideration. I'll be watching this thread to see how your trouble shoot goes, so keep us posted.
 
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