A friend of mine has this truck and recently added a 10# Vortech S-trim to his engine with 145,000 miles. He had previously added a different valve body for hard shifts, once the S-trim was installed he took it to the track and when it hit second gear it destroyed the second gear sprag.

So, he had it rebuilt with the stock valve body and some work done to handle the extra power (est 300-340hp).

Now it seems to work fine until you have run down the hi-way (75mph) for 40 miles or so and when the Autometer gauge reads about 180 degrees F it will just rev up like it is in neutral and then you turn the OD off and there is no D(3) so you slow down and grab (2), it will start functioning again but will sometimes it will rev up in that gear also and then it will have a very delayed 2-3 upshift a part throttle. It is also slow to engage (R) when it is to operating temp. This is all happening with the vortech's belt off so there is no boost.

Any ideas would be helpful I was wondering if this might be an electronic problem. This is the second time it has been rebuilt this month, the first time it did not last 5 days and it was pulled apart and the tranny shop said it had been extremly hot inside and burned up some plates of some sort like it had been run low on fluid, but it had the proper amount in it.

Sorry for the long post.

 

No ideas?

 

sounds like your OD sprag might have taken a dump.

 

Maybe the shop isn't using good parts. The Super Coupe T-Bird trannys had heavier servos and things in them. They are available from FRPP(Formerly Ford Motorsport).
You also might try replacing the neutral safety switch. It also tells the computer what gear the tranny is. I have seen them do crazy things when this switch goes bad. No shift, Drop into low @60mph!!!
Just some ideas,
Jimmy