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AOD transmission won't properly downshift

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  #1  
Old 05-10-2018, 11:53 AM
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AOD transmission won't properly downshift

Hi all,

1985 Bronco 302 EFI /AOD

I'm new to the world of automatic transmissions. I have plans to swap a manual into my new Bronco, but that might not be for a little while so in the mean time, I'm driving it as is.

One issue I keep having is that it's a chore to get it the transmission to downshift when I need the power. Even if I have it floored, it'll upshift as soon as possible.
I don't think I've gotten it the engine to go over 2500 RPMs without manually moving the shift selector to prevent it (1 in down, D on the interstate).

It feels like the shifting is almost entirely RPM based and isn't taking the throttle position into account (unless it's extreme).
IF I can get it to downshift, it'll only be momentarily and it'll quickly upshift again the moment I'm not at 100% WOT. Getting the transmission to downshift requires mashing the pedal into the carpet.

Because of this, it falls out of cruise a lot on hills, and I overall have issues just getting any power out of it (like climbing, accelerating). This makes it a real bear on hills and stuff because it'll just lose speed instead of downshifting into its power band.

It was shifting hard when I first got it, so I've adjusted the ATV cable according to the instructions / specs I've read. Also, one of the first things I did was take all of the slop out of the throttle cable.
Overall, the transmission shifts very nicely, is smooth, and makes for a nice daily driver around town. But, highway driving is a pain and so is getting it to move when I need it to.

Lastly, the throttle cable has had all the slack taken out of it and is nice and responsive.

Any ideas what to do about this? Thanks.
 
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Old 05-10-2018, 12:25 PM
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Your TV cable setting is a little low, increase preload setting 1 notch on the adjuster and test drive. There is a small range of adjustment that is safe to explore.
 
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Old 05-10-2018, 12:54 PM
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I'll take a look at it again, but I've checked it a few times already.

On a few other searches I've done, some are saying a full fluid and filter change did it, while others are saying faulty / warped valve bodies.

Any thoughts on those?

I'm saving up for my manual swap so don't want to put too much into it, but I'm fine with some maintenance since I'll be driving it for a few months.
 
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Old 05-10-2018, 07:38 PM
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Originally Posted by AbandonedBronco View Post
I'll take a look at it again, but I've checked it a few times already..
I'm not suggesting you check line pressure against some spec, I'm saying no 2 transmissions are the same and some will require a little more TV preload/line pressure. So don't bother hooking up a pressure gauge just increase cable preload 1 notch and test drive to see how much the shift behavour changed. If that produces acceptable results you are good, if it moved things in the right direction but it's still shifting a bit too early try 1 more notch. If on the other hand this doesn't make any difference then something inside the trans is bleeding pressure and it's not long for this world, but I'll bet this isn't the case and you will get the results you want with this little tweak.

Originally Posted by AbandonedBronco View Post
On a few other searches I've done, some are saying a full fluid and filter change did it, while others are saying faulty / warped valve bodies..
Nope.. none of that is your problem. This trans has it's share of issues but a global issue like you have here screams slightly low line pressure/TV cable preload. The key point is "slightly" low and that as why I'm suggesting 1 notch adjustment at a time.
 
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Old 05-10-2018, 11:23 PM
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Thanks for all the info, I appreciate it!
I think I've read too many posts about how these will "burn up" if the TV cable isn't adjusted right so I was extra careful with it.
I'll make an adjustment and increase the tension and report back.
 
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Old 05-21-2018, 11:52 AM
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Ok, so I did some adjustments. It seems to help around town quite a bit. (ie. speeds under 40 - 45mph).

However, out on the interstate, it still really struggles to shift out of overdrive.

If I press on the gas at around 50 - 60mph, I have to pretty much floor it. And then it'll usually jump right past 3rd and down to 2nd.
The moment I even slightly let off, it'll go back up to 3rd for about half a second, and then right back on into overdrive.

At 75 - 80, it simply won't downshift into 3rd (I imagine it's locked out of 2nd at those speeds) unless it's completely floored. So, I have to use the shift lever on the column to go into D (3rd) for pulling on hills and stuff.

Any thoughts?
 
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Old 05-24-2018, 10:48 AM
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Originally Posted by AbandonedBronco View Post
Ok, so I did some adjustments. It seems to help around town quite a bit. (ie. speeds under 40 - 45mph).

However, out on the interstate, it still really struggles to shift out of overdrive.
That is a characteristic of the AOD and some are a bit worse than others. Have you tried a quick stab to the floor and then returning to a moderate throttle position? This characteristic is both a curse and a blessing depending upon the engine in front of the trans, I found it was a blessing with a 5.8 as it produces healthy torque at 1800-2000rpm but the 5.0 is a 90lb weakling at that rpm so no so much.
 
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Old 05-24-2018, 12:17 PM
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I haven't tried that but I will. However, that doesn't do much when the cruise control is on. Loses speed and kicks out of cruise on hills, etc.

Seems like it's an odd characteristic that it won't kick out of overdrive into drive when you need it.

Oh well, maybe I just won't worry about it. I would if I planned on having this transmission for the rest of the Bronco's life but I'm not.

Either way, thanks for the help.
 
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Old 05-24-2018, 01:25 PM
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Originally Posted by AbandonedBronco View Post
Seems like it's an odd characteristic that it won't kick out of overdrive into drive when you need it.
For sure, but then this thing is all mechanical so it's all about tolerences and calibrations in the valve body and accumulators. I bet this could be adjusted but I don't know what exactly would have to be changed.
 
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