AOD refuses to shift into 3rd

Well.
I'm trying my hardest to get my v8 powered B3000 shortbox project on the road. I've done most of the work myself including the install of a freshly rebuilt 289 out of a 65 Mustang and a used AOD transmission out of a 93 Mustang.

I didn't bother rebuilding the tranny as I was told that it was working fine when pulled but went ahead and changed the filter and topped up the fluid including the torque convertor. The fluid in the pan was not exactly clean but did not appear or smell burnt and there were no bits of clutch material that I could see.

After watching several online videos about the correct way to set the TV cable I thought I had it right and took it for a test drive. Results were lazy shift between 1/2 and absolutely no 3/4 shifts. Took it back to garage and put a 100 psi gauge into the TV test port on passenger side as described.

Apparantly the idle pressure supposed to be 0-5 psi raising to around 25 psi with the 5/16" spacer gauge installed.

Well. I couldn't get the pressure below 16 psi no matter what I did. The engine was idling around 900 rpm. I tried pushing the lever back with my fingers but it was already at the zero position.

At approx 4000 rpm the gauge showed close to 75 psi with a gradual rise (not jerky) at the rpms in between.

I played around with the ratio between carb/throttle lever and TV lever movement and although I was able to get 1st and second feeling right, there was still no shift or attempted shift to third gear.
I verified the newly installed B&M shifter and cable were selecting the "D" detent on the transmission properly

Does anybody know what the problem might be ? I'm wondering if it might not be a dirty VB or stuck 3/4 servo ?

Maybe I should've just bypassed the AOD and went with a C4 but I was looking for something that could give me some decent fuel mileage when I was out on the highway

Pressure should be around 30 psi at idle.

allnpt0 said:

Pressure should be around 30 psi at idle.

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Is that what you truck is set at ? I find so much discrepancy on what the damned pressure is supposed to be set at depending on what source or website your visiting.

The general consensus from many others is that it should be be between 0 and 5 psi with 3 being optimal but I really doubt most gauges are capable of that kind of accuracy anyway. I have heard of others that are using much higher pressures like yours with excellent results.

Do you have any idea what your pressure is like at 1/3 throttle (or approx where the transmission would be shifting up)

I really hate to yank the tranny and start tearing into it if all that is ailing it is an improper TV setting.

Per Mitchell1 repair manual:

OK thanks. That's the info I have too. Now your 30 psi makes sense because with that gauge inserted you are moving the cable forward 5/16" from idle position where I'm told the tranny should then be around 0-5 psi.

Even with my lever all the way back and no TV gauge it just won't go below 16 psi.

From idle and as soon as I depress the pedal, (ever so slightly) I'm at 25-30 psi. I took the engine to about 4500 rpm and went over the 100 psi mark on the pressure gauge so I know the pump is working fine. (by the way - I learned you don't do this unless your test hose is clamped to both the gauge and barbed fitting that inserts into the tranny - it takes only a few seconds to pump a few quarts of hydraulic fluid onto your nice previously clean garage floor when you strain the press fit connections with higher pressures)

So - I wonder if this higher idle pressure could be an indication of a problem in the valve body ???

... or ... is it possible this is due to a shift improvement kit or some other mod the previous owner did ?????

Will it manually shift into 3rd? You can manually get an AOD to go to third by manually starting out with the selector in the 1 position and let it get to 3000 rpm, then go to 2 and let it shift to 2nd, immediately go back to the 1 position as soon as it shifts (this will hold 2nd). Then get up to around 3000 rpm and put it back into 2, and hopefully you get 3rd gear, and then OD when put the selector in D.

myagi said:

... or ... is it possible this is due to a shift improvement kit or some other mod the previous owner did ?????

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This is possible. Might have some stuck valves (most likely 2-3 valve).

this has nothing to do with your problem but if your motor is idiling@900 you may wanna check your tps sensor and make sure its fully closed i think it should read around 0.90-1.0volts. you can check it with a multimeter the red lead on the meter goes to to the green wire of the tps sensor and just ground the black lead from the multimeter. make sure you are on dc .

morse johnson said:

this has nothing to do with your problem but if your motor is idiling@900 you may wanna check your tps sensor and make sure its fully closed i think it should read around 0.90-1.0volts. you can check it with a multimeter the red lead on the meter goes to to the green wire of the tps sensor and just ground the black lead from the multimeter. make sure you are on dc .

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Ya... Sorry but I forgot to mention the 65 Mustang 289 has the original intake and 2 bbl carb. No EFI

So, I didn't know about the manual shift trick but I'll give it a try. Interesting but even if this works, it probably means sticking 2-3 accumulator right ?

myagi said:

Ya... Sorry but I forgot to mention the 65 Mustang 289 has the original intake and 2 bbl carb. No EFI

So, I didn't know about the manual shift trick but I'll give it a try. Interesting but even if this works, it probably means sticking 2-3 accumulator right ?

Click to expand...

You learn these tricks really quick when you own a Mustang with an AOD. It didn't last long before I did a T5 swap. Much betta!

Sent from a Commodore 64 using a 300 baud modem

Well I swapped the tranny out this weekend and cracked the pan on the original unit to find evidence of clutch material swimming in the brand new fluid that I had just topped up after the install.
It's so hard to believe that less than 5 miles of driving would have done this when the TV pressure setting was no less than 15 lbs at idle and maxed out at around 90 psi at WOT. I'm thinking the tranny was causing problems for previous owner before I bought it ?

The swapped unit was from a low mileage Econoline van which appears has never had the pan off (dipstick plug still in the pan)

I have the remainder of the shifter & TV connections to do, then set it up with a fluid gauge in the TV port.

So what is the consensus for setting up the AOD TV pressure; 0-5 psi at idle with 20-25 psi using a 5/16" spacer or set it for WOT, carb/TV lever ??????

30 with the spacer

33 PSI at Idle.

Thanks to all for your input. I finally have the truck on the road. Setting up the TV on the new / used unit wasn't all that hard but I used a pressure gauge ,started with 0 psi at idle and watched the shift points with the rear axle in the air. Because there was a possible difference in the amount of TV cable pull vs carb linkage pull due to the custom linkage I had to fabricate to make this work with the stock 1965 carb, it took some tweaking until I was satisfied the transmission was shifting like a factory AOD.

My gauge shows about 35 psi when I move the TV linkage 5/16" with the tranny in neutral.

The shifts points are at fairly low rpm and don't really suit the higher revving 289 because the only unit I could get my hands on were out of an Econoline van. I might swap out the governor from the other Mustang unit for the time being.

I'm going to rebuild the other tranny over the winter and put some tougher upgrades into it while I'm at it. I've never done one before but I'm confident there are lots of knowledgable sources out there to help me along.


Tks again to everyone. I'm going to work on posting an article on my build in
the very near future