View Full Version : AOD Problem - No AOD or drive

04-04-2003, 10:13 AM
My beloved 90 SC is hurting.......
Here's how the problem started...I'm travelling up the Interstate and start passing a transport. The car downshifts fine and I start to pull ahead when suddenly the car upshifts really hard, the radio quits momentarily, the upshift light comes on and off repeatedly, and the tranny feels like I'm in neutral. I pull off to the shoulder and coast to a stop.
All I have now is 1st and 2nd gear. It does shift between those two gears fine. I drove the car home @ 45mph at 3,000rpm. That's the best it will do. It will not shift automatically into drive or overdrive.
The only problem the car had previous to this was that it would on occasion shift hard from second to drive.
Any ideas what broke? Is this repair going to break me???
The transmission fluid level is fine...
Please help.......

Aaron Pedroza
04-04-2003, 12:15 PM
Take a look at this link. I am far from a tranny expert but it doesn't sound good.


David Neibert
04-04-2003, 12:41 PM
It sounds like the inner input shaft broke. It is sometimes called the 3-4 shaft because it provides power for 3rd gear and OD. The inner shaft is attached to a set of splines that are welded onto the torque converter.

That is why 3rd and overdrive are always locked. Lentech sells a hardned inner shaft. If that is what happened the transmission will have to be removed to replace the shaft, it is a simple repair and the shaft just slides in. However now that the transmission is out, you should seriously consider a full rebuild.


04-04-2003, 12:53 PM
Thanks Aaron...after reading that link I went out and tried a few things. The oil does not smell burnt, but it's not bright red either. There does'nt seem to be any metal particles in there.
I can't even get into 3rd...anything above 45 mph and it seems like it is neutral...it will rev and then if I let go of the gas, the revs will drop to idle speed. When I get down to 30 - 35 mph, I can get it back to 45...maybe 50 then that's it.
The TV cable is still attached...no unusual noises coming from the tranny...I just have the slowest SC out there right now. :o(

I do agree with you....it does'nt sound good!!!

04-04-2003, 12:57 PM
David...is there any way of confirming that the shaft is busted besides pulling the tranny? Hate to order a part that I may not need....

David Neibert
04-04-2003, 01:08 PM
There might be, but I don't know how to do it. Look for a guy named A-Train on TCCoA..he seems to know the AOD pretty well.


Aaron Pedroza
04-04-2003, 01:12 PM
It sounds like it actually shifts into 3rd but it just slips. Common way for our trannies to go out. Had it happen to me like that twice before. Then I learned and spent some money to build a real tranny.

04-04-2003, 02:06 PM
I just finished reading TCCOA's common problem's with these tranny's and it sounds like the direct clutch may have gone out. If it did, it sure went quick. No matter what, it's rebuild time. Any one know of a good tranny shop around the Wilson NC area? Any place furtherand it will take me days to get there in second gear...

04-04-2003, 02:31 PM
I just put in Lentech Street Terminator AOD in my stock 1990SC. With TV cable and electric delete. This is my 3rd tranny. The first one went 100k the second 60k; I tow a boat.

WOW what a difference. My personal review is this tranny is what FORD should have had in this car to begin with. From a stop, I can put down the pedal and burn as much rubber as I want to pay for. With moderate acceleration I now chirp going into second at 3000rpm's, (yes at 3000, ~~~) so I am real light on the pedal lifting it up at 2000rpm. Before the tranny would just SLIP into first or second gear. OR if I adjusted the TV cable it would shift harsher/bang but no rubber.

It grabs like a manual tranny, with automatic shifts.
With the Lentech ST Plus it probably chirps in third?

The shifts 3 to OD, and OD to 3 are nice and tight vs the stock tranny which likes to SLIP. Also the BANG into OD is gone.

Downshifting from OD to 3rd is a bit to tight when deaccelerating to a stop when I delete the OD?

With the non locking torque converter the 'upshift light'
probably comes on 500rpm sooner, which may be a problem for racing?

The guy who installed it, BENT the dust cover, sheild, whatever, and it made such a racket I thought he forgot to bolt on the exhaust. Apparently it is difficult to remove the tranny without bending the cover plate. I brought it back 2 times now and it still is noisy, so he is going to order a new plate.