Here we go again!
Just took the car out for the second time after the rebuilt AOD transmission was installed 2 months ago.
And again the car once in drive start to over rev like it’s in neutral!
Had a pressure tester on it and had it setup at 36.
I may have driven 1 mile in total.
What might be wrong and did I drive it far enough to screw up the transmission?
I ended up boosting our AOD Throttle Valve Pressure to 39 PSI to get our AOD we transplanted into our 73 Mach 1 to increase the road speeds at which the 1-2 and 2-3 upshifts occurred (and the 3-4/OD upshift). A little added pressure won't hurt anything, but too little pressure will cause problems. Increasing the TV pressure may not solve the problem you are seeing, but it may be worth goosing the TV pressure a bit to see.
In your description you mention slipping in "drive," but I could not tell if you meant 3rd gear direct 1:1 "drive," or the 0.67:1 "OverDrive drive" gear when the slipping was happening, In a later comment it sounds more like when you are "at speed" (30 - 35), when you should be in OD. If that is correct it is entirely possible the OD band needs to be adjusted. See:
https://www.therangerstation.com/forums/index.php?threads/aod-band-adjust.145388/
An aside, I never rebuilt, much less worked on, an AOD, as by the time they were coming out I had migrated into corporate
White Collar America, providing computer solutions to car dealers. But, I can tell you this... With the C4, C5, FMX, and C6 transmissions I preferred to adjust bands with the tranny at normal temperature, just to make certain I was not leaving the adjustments a little too loose or tight by only bench adjusting the bands with a cold tranny. Any time I burnt smelling fluid, or a slipping transmission, I would replace all the ATF, including draining the converter, replace the filter, and adjust the bands once the tranny was filled with fresh ATF (the correct type of fluid). Unless the rubber seals for the servo or clutch pack units were hardened and leaking internally, or the valve body had a problem, in the majority of cases the band adjustment is what made all the difference in how the tranny worked. And, often it was a loose band adjustment that allowed the fluid to become burnt. Of course, if someone drove their car too far with a loose band, and the ATF just got more and more burnt, the fluid and Band Adjustment approach would be futile. But, I was working on mostly newer cars at a Ford dealership, so often I caught the transmissions with loose bands in enough time to be able to breath new life into them with new ATF and a band adjustment. For C4s I had a few little tricks with the valve body I would do that improved the crispness of their upshifting, preventing the little bit of band slippage in the 1-2 upshift that was meant to soften the upshift feeling for the comfort of the driver. I always felt that little bit of "slippage by design" did more to cause problems than it was worth.
If your problem persists, and I suspect it might (but I hope the band adjustment takes care of it, or the TV pressure bump), it would be a good time to get a technical manual that covers AOD diagnostics, and use the oil pressure ports, with oil pressure gauge(s), and see if you can identify the problem through hydraulics pressure at the time of the slippage.
Personally, I am absolutely thrilled with the AOD we swapped into our Mustang, especially with the impact on engine RPM at highway speeds with our 3.5:1 TractionLok rear axle gear set. But, in retrospect were I to do this project again I would have opted to use a 4R70W, or even AOD-E, tranny with an external electronic controller, as it would have been far easier for me to manage the various upshift speeds for the 1-2 and 2-3 (and 3-4) upshift points. Further, allegedly the 4R70W is a more rugged, stronger transmission than the earlier AOD and AOD-E units. We are fine with the strength of the AOD with our 360 HP 351 engine, as reportedly the AODs can handle 450 HP in stock form, and upwards of 600 HP with some upgrades. We do not race the Mach 1 on the streets or on track. It is just a cool cruising machine. So, the AOD ought to work out nicely in the long run for us. The external oil cooler, and use of high quality synthetic transmission fluid ought to help in that regard.
