1985 F150 4x4 - 302FI - AOD - Is there any fairly simple way to make the trans lock into second gear? For instance, can the control be over-ridden so that once in second, it'll stay there? A valve in a vacuum line, or some aftermarket kit? Or is this near-impossible?

 

No way? Can't add a vacuum valve somewhere, or something?

 

The AOD is purely mechanically-controlled, no vacuum applied to it nowhere. You pretty much have only a shifter which tells it how high to upshift, and a TV cable or rod that tells it when to upshift. The only way I'm aware of to keep an AOD in 2nd gear is what's known as the 1-3-1 shuffle, as in you keep the shifter in 1st for a while then put it into 3rd and almost immediately drop it back into 1st - upon placing the shifter in 3rd the trans will upshift to 2nd or 3rd gear, but when you place the shifter back into 1st if the vehicle speed is too high for the actual 1st gear in the trans she will downshift to 2nd and stay there till either you put the shifter back into 3rd or OD, or slow down enough for the trans to drop into 1st again. I've done something similar when descending steep hills, basically I come up to the top in 3rd gear then when I start descending on the other side I put the shifter into 1st, the vehicle speed is too high for the AOD to engage the real 1st gear so she drops down to 2nd and stays there. The 1-3-1 shuffle is not good for the trans, however what I used to do is supposedly fine, forgot why exactly that is...

Or, you can buy an aftermarket valve body from Silverfox, he makes one that has an electric solenoid for the OD gear so now your shifter does actually allow for a manual 2nd gear and you shift in and out of OD with a push button or a switch, much like how the E4OD trucks are operated.