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post #1 of 4 (permalink) Old 06-30-2012, 06:23 AM Thread Starter
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Join Date: May 2008
Location: Sweden
Posts: 86
Change or repair?


I have been asking a lot of questions on this forum and got answers that had helped me with the T-bird, so thank you all for these answers. Some questions was not needed as they was allready asked and answered by some one else.

I have done some modifications over the year that I have had the car (11 years) and so far they are:
3.08 to 3.55 including a Ford Racing Diff, Half shafts made in tool steel, the complete rear axle frame welded and support bars, Vogtland lowering springs, Koni adjustable shock, support bar between shock towers in trunk, front brakes from Mustang which needed 17"rims, engine from Mustang GT-04, 255 fuel pump, 24-injectors, cold air intake, and as a result 223 rwhp. There are more modifications, which I for the moment do not remember. I do some each winter and drive on the summer.

Now to my question and that is about the Aut. I have the 4R70W and it now seems to have reach the time of its life where it should be rebuilt or changed. What is your opinion? As the Aut is from 94, I think that it is of the first models of that Aut-type. Is it wort rebuild or should I buy an other? There are the 4R75W. If I should buy, from which models should it be?


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post #2 of 4 (permalink) Old 06-30-2012, 06:36 AM
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I would ditch the 94 transmission and get a 99+ to put into the car, ideally 03+ even. Keep in mind that you will need to re-pin the transmission harness to install it, and you will also need to re-use a few of the electronics from your transmission.

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post #3 of 4 (permalink) Old 06-30-2012, 06:30 PM
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Join Date: Jul 2010
Location: Lapeer,Michigan,USA
Posts: 58
Hello Berth, seeing that you are in Sweden I would only be guessing that the parts/salvage yards in your neck of the woods are overflowing with Ford drivetrain parts on the cheap as they may be here.
I did notice that you did NOT mention your power upgrading has caused the immediate failure or weakening of your transmission, there a LOT of early model transmission haters running around so take heed of advice given.
Personally, if I were you I would rebuild your original unit using the late model "Hi-Energy" clutches and OD band, a full bushing & bearing kit along with the molded rubber accumulators and springs for your desires of "shift feel", upgrading to a mechanical diode reverse drum would be the final word, but I would not hesitate to use the original roller clutch as long as the snap ring is replaced with the "spiroloc" retainer if revs over 5500 are in the plan, if you get a good deal on a Mark VIII drum with 14 rollers, hit it.
As long as the modifications to the shift qualities don't involve tire squealing antics, you should be just fine, aim for "Firm/Solid or Positive" shifts and you will be golden.
As for parts supplier, I would believe Alan at DirtyDog might be familar with your needs and knowledge of shipping overseas, there may be others also, but he seems to be the go-to man around here.
Best of luck from afar,

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post #4 of 4 (permalink) Old 07-01-2012, 04:25 AM Thread Starter
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Join Date: May 2008
Location: Sweden
Posts: 86
Hello and thanks for your answers. I will run it this summer as it is, then it is a decition for the winter. The problems started before I changed engine. Rebuilt is something, which I will not do by my self. Buy a new and put it in the car, that is something I can do. I bought the original service book when I bought the car. It is thick as a bible and it is a bible about the car. I have read the section about the Aut and then I did see that this was not a job for me.
There are T-birds of the MN12 type here in Sweden, but I'm not sure how many of them that are rebuilt. Have not found any. If you want a Ford then they o for the Mustang, which is much more easy to up-grade. There are a lot of things sold for the Mustang, but none for the T-bird. That is what I like about mine; there are not that many of them around.

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