AOD severe shift problems after rebuild - TCCoA Forums
 
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post #1 of 6 (permalink) Old 06-20-2004, 12:00 PM Thread Starter
 
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AOD severe shift problems after rebuild

1993 FORD AOD transmission (1993 Thunderbird Super Coupe)


Symptoms:

- Late / erratic / no upshifts.
- Stubborn downshifts / no downshifts.
- Stuck 3rd gear direct clutch stalls engine when coming to a complete stop.
- Symptoms grow worse after the vehicle is driven for any length of time.


History:

The transmission was rebuilt recently. Here is a list of the parts used:

- Newer 4R70W wide-ratio planetary gear set components, clutches and bands, and new 1-2 accumulator.
- New tail shaft Governor.
- Rebuilt (stock spec) torque converter.
- LenTech street terminator valve body (specifically calibrated for the OEM torque converter and wide-ratio gear set).


Discussion:

When cold, the transmission will shift properly, but not as smoothly as it should. Additionally, the shift points are not consistent (at the same RPMs for any given speed/throttle setting).

It appears that the transmission starts to refuse to shift properly, either up or down, after being driven for a period of time. This results in very high engine RPMs before it will shift, even at very light throttle. Shifts are always very harsh at this point no matter what the RPMs.

Further, when it does reach 3rd gear it seems to stick there, and will stall the engine when the vehicle is brought to a complete stop. Pulling the shift lever back to 1st gear is the only way to force 3rd gear to dis-engage. Once it is in 1st, it refuses to shift into 2nd until engine redline is reached no matter how little throttle is applied.

Along with this, the transmission will not downshift at low vehicle speeds even if the throttle is fully open (gas pedal floored). Clearly, once the transmission is fully warmed up, it stubbornly refuses to upshift until excessive engine RPMs are reached, and will not downshift at all.

Timeline:

Transmission was rebuilt but the stock valvebody was cleaned and re-used. The tail shaft governor was replaced with the rebuild. It displayed all of the symptoms listed above. Next, the tail shaft governor was replaced (again, with a unit supplied by LenTech) and a new LenTech street terminator valvebody was installed. The symptoms remain the same.

-----------------------

I’m at a loss as to what to do next. The transmission shop that originally did the rebuild could not solve the problems, and that’s why I had the governor and valvebody replaced (by the local dealership). Several transmission experts have stated that it’s either a sticking governor or faulty valvebody, but in my case both have been replaced with new components (?). Does anyone have any advice at this point? This has become such a nightmare for me and I’ve already spent a bundle of dough on it… what could possibly be wrong that everyone has overlooked?
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post #2 of 6 (permalink) Old 06-20-2004, 11:12 PM
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While I too would first suspect a faulty valvebody or sticking governor, it's also possible the direct clutch was built with too little clearance. It could be built tight enough that it's still partly engaged, or whoever built it might not have paid attention to whether the steels really fit the drum well enough. Could also be gasket crossleaks in the VB, but I would expect if that were true the issue would have been resolved already. The fact the VB is new would be the most suspect thing IMO. In any case, the shop should take care of it.. you paid for a working transmission, and they should have provided it. Walk in with a cell phone and a phone book. If they give you hassle, turn it to the page marked "Attorneys" and pick up the phone... maybe that will force the issue if they don't cooperate.

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post #3 of 6 (permalink) Old 06-21-2004, 03:58 AM
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he could scare the shop with the attorney thing but, the local dealership already messed with it, so all that would do is start the finger pionting in between the shop and the dealership.

it does show that the shop has bad customer service, they should of corrected the problem before they released the vehicle to the customer, even if they would of had to send it off to get rebuilt somewhere else, the shop would of had to absorb the cost.

sorry about your tranny, though. wish i was a tranny guru and help you out, but the best thing to do is try to get the shop to redo thier work on the tranny, or at least replace it, hth....later'z.....

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post #4 of 6 (permalink) Old 06-21-2004, 04:05 AM
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but then again, if he brought the parts to the shop himself, they probably will not do warranty work as most shops cannot or will not warranty parts that they did not provide.

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2004 Mercury Grand Marquis GS
Pioneer DEH-P6000UB Infinity 2 way 6x8's, and Eclipse 5x7 3 ways, Fultron Tweets, Infinity 1211A, Alpine SWR-1222D Type-R 12.

1999 VW New Beetle SOLD!

1990 F150 Lariat Xlt 4.9L std cab longbed, E4OD, Work Truck.

1994 F150 XL 5.0L 4R70W Current Project.


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post #5 of 6 (permalink) Old 06-25-2004, 11:21 PM
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not for nothing, but did anyone check the t.v. cable? if not set right, the tranny will not operate correctly. just a thought.

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post #6 of 6 (permalink) Old 07-10-2004, 05:52 PM Thread Starter
 
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First, I would like to thank all who replied... it's always helpful to get other opinions and advice with tough problems like this.

After gathering all the information/opinions/advice from various sources, all the evidence points towards fluid contamination.

My transmission is now in the hands of another mechanic, who is regarded as a top troubleshooter (other shops send cars to him when they can't figure out the transmission problems). He dropped the pan initially and found it full of black silt (which corroborates the contamination theory). The source(s) of the contamination is/are still unknown however, and complete dissassembly/inspection is the next step.

I have since learned that there are two basic sources for contamination: internal and external. Since my present radiator is the OEM factory-installed one, I put in an external cooler and bypassed the rad cooler for now (until I can get Mike38sc's radiator installed, then I'll connect both) in order to eliminate this as a potential source. Some have told me there were cases where you couldn't thoroughly clean the OEM coolers no matter how much you flushed them.

I'll post again (for those who are interested) when I have more information on the progress of my tranny...
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