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1973 Mach1 Transplanted AOD Throttle Valve Pressures In Both Neutral And Park

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I had another automotive enthusiast ask if there was a difference in the Throttle Valve (TV) pressure levels between Park and Neutral. I had always set my TV pressure with the AOD in Park. But, our colleague advised the manual specified it should be in Neutral. Okay, fair enough. It is a valid question despite what the manual may say, but with what the manual says it is even more important to find out if there is a difference or not. And if there is a difference, how significant is it?
Also, it is worth mentioning that I have done the TV pressure testing and adjustments when the engine and transmission are in normal operating temperature, and with the AOD fluid level being at its proper level. I had not mentioned that in my prior video, and as pointed out to me by "Bentley Nut" in a pleasant comment, I should have done so.
What I did not show in this video is what it took to get the Oil Pressure gauge connected to the center test pressure port on the AOD. I have a link below that shows a prior demonstration re: how to check and adjust TV pressure on an AOD transmission after installing the oil pressure gauge in the proper test port. Please feel free to watch the other video (link below) for more information. This video you are looking at currently (9/7/2022) is really more about showing how much difference there is in Neutral and Park in the TV pressure when using the 0.275" thick spacer tool. More info re: the 0.275" spacer tool, and how to adjust the TV pressure, is found in the videos in the link below:
• AOD Line Pressure Port...
In short, the TV pressure in Park in this video is 39.5 PSI. In Neutral that drops to 38.0 PSI. So, I saw about 1 1/2 PSI difference between Park and Neutral positions. That is not a lot of difference, but it is enough of a difference for me to say that, yes, doing the TV setting and measurement would be more correctly done in Neutral as opposed to doing it in Park.
In my case I intentionally went higher than the 30-35 PSI specification from Ford, as I wanted to increase the speed at which the 1-2 and 2-3 upshifts occurred, along with a firmer upshift. I had set it to 39.5 PSI, and figured it was close enough to 40 PSI to call it done. The upshift speeds indeed increased a little bit, and the upshift are firmer, just as I had anticipated.
The nominally higher TV PSI is not going to hurt the transmission What hurts these AODs is when the TV pressure is not high enough, which can occur for any number of reasons - one of which is when some older plastic or nylon bushings fail, and the cable length to the TV linkage is effectively lengthened, which causes the TV pressure to drop enough at time to cook the internal friction plates.

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25 авг 2024

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@gilberthale7777 Год назад

In a prior video I received a comment from @Bentley Nuts where he made some suggestions and asked a question. The question was if there was a difference in the Throttle Valve PSI pressure in Park and Neutral. Well, I never noticed any significant difference in other transmissions between Neutral and Park before, so I thought I ought to take the time to find out. Now, doing this kind of Throttle Valve (TV) pressure check (and adjustment) is not one of those “all you have to do is” kinds of operations. It is not necessarily hard to do, but it is tedious when it come to hooking the Oil Pressure Tester to the AOD. I did not cover that process in this video, but I do cover it, and how to adjust the TV pressure, in an earlier video at: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-KYIAqqYUKNo.html It turns out there is a small difference in the TV pressure depending on the AOD being in either Park or Neutral. It is a difference of about 1 ½ - 2.0 PSI. I should also note, the TV pressure is measured when the engine and transmission are at normal operating temperatures. If you adjust the TV pressure in Park, set it 2 PSI higher than you are wanting to run at, so in Neutral it will be closer to where you want it to be. The factory specs for the TV pressure that I have found say to set the pressure to 30 - 35 PSI. I intentionally set ours a little higher (40 PSI in Park) as I wanted my 1-2 and 2-3 upshift speeds to be higher than “normal,” and firmer. Having a TV pressure setting a bit higher than spec is not going to cause damage to the AOD. What damages them is when the TV is too low, as it causes the friction material in the clutch packs to burn out. This often happens when the plastic or nylon bushings using in mounting the TV pressure cable gets brittle and breaks, leaving the TV cable a little more slack than it was originally, which lowers the TV pressure. Too soon the lower TV pressure takes its toll on the AOD.