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Hello evrybody..! this is my first post !!:)
I am a retired senior whom in the 70's work on C-4, FMX and C-6, that operated with modulated pressures and had a governor on the output shaft, and engines that were carburetted. Have managed to maintain my ASE Master Auto Tech cerification to keep my ego up to date, and tinker with my cars and those of the next door neighbors, but had little or no hands-on experience with the newer transmissions and NONE with the 4R70W that is on my 97 Towncar. Here is where I need your input.

My 97 Toncar has 122,347 miles on the clock, I can notice that the engine rev-up (slipping) just as it tries to shift from 3rd speed to 4th speed, but if I release my foot from the gas pedal, then the shift occurs at 40MPH or above (not under) and the car pulls on strong. When I drive in the city, most of the time is under 40MPH and the car is always in 3rd gear when the selector is in "D" and city fuel consumption is avg. 15-17MPG but if I pass over 40+MPH, then it shift into 4th. speed by releasing my foot from the gas pedal and highway consumption is 23-24MPG , and then I can coast dow to 33-35MPH and it holds the 4th speed, but if the speed falls under 33-32MPH, it shift back into 3r gear automatically. I am thinking of buying a set of pressure gauges to start with from there and take the guessing out of the picture..LOL

I have been reading several of your treads and postings trying to educate myself and have learned a lot and will happily welcome any suggestions you might have.
 

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The fix for the earlier transmissions is to swap in a later one. :)

I'm using '02 Gran Marquis transmissions, but towncar transmissions will work, iirc.

I believe you are held to the pre-03 transmissions as well as us. There were changes in the Vss sensor after that.

I'd look for an 99-02 low mileage tranny, if it were me.

Take a look at the tech articles, accessable from the front page, as well as the stickys in this forum.
 

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Town Cars have a longer tail shaft than the Grand Marquis, so they won't work unless you want to swap the tail shafts.
 

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Thanks for suggestions, Grog6 and Dusty: altough a newer-low mileage tranny will indeed be plausible as an alternate solution, I would rather first try to fix mine, if possible after trying those Sonnax fixes on the valve body: i.e. oR&R the pressure regulator valve and the OD Servo Boost Valve & Sleeve, thus it looks in theory from my perspective, that either the OD band is slipping for lack of pressure..or probably is toasted?
I would need to verify that by taking pressures, thus will need to buy a set of gauges., or just go ahead on my gut feeling and do the valve body work?
Do you agree?
 

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You can buy parts from DirtyDog, he may be able to tell you what will fit in a later case style.

http://www.dirtydogperformance.com/transmission-rebuild-kits-and-parts/aod/aode/4r70w/cat_23.html

I'm using a 03 towncar engine for my pi buildup; I'd bet an 02 towncar tranny would fit your TC. :)

There were changes in the internals that make it a much better platform, even if you have to rebuild it. better valve body, mechanical diode, even different sized ports in the casting.

If it has the same long tailhousing as the police cars, make sure you don't accidentally get a police car tranny; police car 'anything' are beat to death.
 

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Discussion Starter #6
Thanks Grog6 for the link to Dirtydog parts. I see that he has a 2" highcarbon OD Band that I might consider buying as well as other parts once I tear down the transmission? ! As to the etension housing length and ID and I think my application is almost one inch longer on the Towncar. Baumann Engineering has several interesting articles on the 4R70W Swaps, upgrades and modifications as well. They indicate that the Bellhousing pattern is different for a 4.6Lt or 5.0/3.8L/4.2 and the two are incompatible, etc.
Also the mechanical diode came in 1998 onward and I dont know if I can fit one of those in my 97 tranny?.but I wont mind using just the regular application, thus my engine is just a 190HP single exhaust 4.6Lt.twin cam, so there is not enough Juice to burn rubber" LOL.
 

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Sounds like you are not afraid to dig in to the transmission so go for it. Labor is a big cost in a rebuilt. DirtyDog is a good source for parts and some advice. For most of us it is cheaper and easier to get a 99-02 yard transmission, repin the connector, change the MLPS, and the TCC solenoid.
 

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Dusty.. you all are probably right.. Today I called several yards and one had a 4R70w + converter from a 1999 Towncar for $250 . The guy could not tell me the mileage or condition of the transmission, but offered me 30 days warranty as is?, I do not know if that 99' converter will couple with my 4.6 Lt, 97 engine flexplate, nor if I have to repin the wires to the MLPS. I assume I will have to do some other modificatios as well. Do you think I should open it and see the guts inside and/or overhaul it before installation?
Will appreciate any advise or hint from you all and what to look before purchsing it.
Thanks.
it also have a mechanical Diode What would you advise I shall look or need to look before purchasing it for compatability. Any codes? How long should be the extension housing tail
 

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$250 a DEAL for a good Town Car Core alone IMO so I'd overhaul it anyway - 99 4R70w would already have a Mech Diode in it - If you dissassembled any replacement Tranny you can swap out the longer Extension housing & related parts to any fresh Tranny.
 

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I do not know if that 99' converter will couple with my 4.6 Lt, 97 engine flexplate, nor if I have to repin the wires to the MLPS.

... it also have a mechanical Diode What would you advise I shall look or need to look before purchasing it for compatability. Any codes? How long should be the extension housing tail
There are 4r70Ws for 6 cylinders, that also fit the 5.0 block. Make sure the one you buy is for a 4.6l.

The 99 converter is better than your 97, use it.

You will have to repin the tranny connector for a 97; it changed in 98.

99 has most of the updated internals.

It will bolt up to your flexplate. IIRC, these are all 12" converters. The flexplate nuts are SAE SIZE! I always strip one of them with a metric wrench before I remember, lol.

To change the tailshaft, the shaft is the first thing into the case, and the last thing out. Be warned, it's not easy. :)

Good luck!
 

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Ok Guys.. Thank you all for your good advises..Will call the Yard tomorrow to see of the transmission is still available and would go from there..or otherwise, drop my transmission down and rebeuilt it.!
Will keep you posted of my progress. Thanks again
 

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Ok Guys.. Thank you all for your good advises..Will call the Yard tomorrow to see of the transmission is still available and would go from there..or otherwise, drop my transmission down and rebuild it.!
Will keep you posted of my progress. Thanks again
From this post, you can use a police car transmission, which is the right tail:

http://forums.tccoa.com/showpost.php?p=1368351&postcount=8

98-03 are best, and you will have to repin the harness, IMHO.

Low mileage police car wrecks happen too!
 

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Police transmissions are identical to town car transmissions. 97 is not a really bad year however it will probably still be cheaper just to get a good used one.
Alan
 
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