Failed AOD Rebuild

Failed AOD Rebuild

Mpyrol
Mpyrol

March 17th, 2005, 3:42 am #1

I have a 90 f150 with AOD and after pricing tranmission repair I decided to tackle the rebuild by myself. If I pay myself $200 a day for three days and buy parts I do a little better than break even and learn some things.
I completed the rebuild and at present I have reverse and 1st. The transmission will not come out of 1st, and I fear the 2 mile trip around the block may have not been so wise. I have a couple of things I am uncertain about.
The governor had some rotational movement on the shaft, may be 10 degrees. Is this right? I remember it being a bear to slide off. I do have the ball in it. I am sure it's not backwards.
The TV lever arm on the transmission seems to float in the middle of it's range of movement, is that right?
The 2-3 accumulator piston has a pretty stiff spring and I can't see how such a loose fitting piston with these teflon seals could have enough buildup in pressure to actuate the piston with no blow by. I assumed it worked when I took it down.
I had all the pistons installed at the transmission shop, I did ruin one seal installing it without the guides. Any suggestions or comments are appreciated.

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Mark
Mark

March 17th, 2005, 9:49 pm #2

The govenor may look correctly positioned, but if the governor ounter weight is backwards the holes will not line up. A little bit of rotational movement is o-k. 10 degrees is kinda pushing it. A lot of guys cut a small piece off a rubber o-ring to install under the ball that positions the govenor. This is not a really a good modification in my opinion. AOD books do not detail the function of the counter weight. Yet older Cruise-O-Matic books do, and the AOD shares the same govenor design as the old Cruise-O's. The govenor is suppoed to fit slightly loose to bleed off some gov psi at low speeds. Then as the vehicle moves faster, centrifugal force on th gov counter weight pulls the govenor to seat tighter up against the output shaft. In turn creating a better seal and tranfering more gov psi. Those who do shim the ball effectively narrow the range of the govenor.
What do you mean the TV lever floats? As in lateral play---in and out?
About the 2-3 accu piston, I preffer to upgrade to the bonded 2-3 piston from the AODE/4R70W.
Are you sure you have the TV psi set correctly?

Mark Piechowski
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mpyrol
mpyrol

March 18th, 2005, 1:34 am #3

When I put the TV back in and locked the spring it was not all the way to the rear of its motion. Now that I have run the vehicle I see it is retracted all the way. I just left adjustment alone as it looked proper. It worked fine when I took it out. Contrary to my to initial post I do have 1st and second however to get into low I have to manualy shift to low.
Let's assume the TV is adjusted properly. The play in the govenor probably isn't 10 degrees. If a small amount of play is normal it's fine. Could the govenor be faulty? Everthing in the transmission looked clean and other than reverse it worked good. Other than putting the governor on backwards (not likely) whats the next most probable cause? I mean it may be highly unlikely that it isn't the gov or tv. I'm going to pull the extension housing and hope I made an error.
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mpyrol
mpyrol

March 22nd, 2005, 1:39 am #4

The govenor may look correctly positioned, but if the governor ounter weight is backwards the holes will not line up. A little bit of rotational movement is o-k. 10 degrees is kinda pushing it. A lot of guys cut a small piece off a rubber o-ring to install under the ball that positions the govenor. This is not a really a good modification in my opinion. AOD books do not detail the function of the counter weight. Yet older Cruise-O-Matic books do, and the AOD shares the same govenor design as the old Cruise-O's. The govenor is suppoed to fit slightly loose to bleed off some gov psi at low speeds. Then as the vehicle moves faster, centrifugal force on th gov counter weight pulls the govenor to seat tighter up against the output shaft. In turn creating a better seal and tranfering more gov psi. Those who do shim the ball effectively narrow the range of the govenor.
What do you mean the TV lever floats? As in lateral play---in and out?
About the 2-3 accu piston, I preffer to upgrade to the bonded 2-3 piston from the AODE/4R70W.
Are you sure you have the TV psi set correctly?

Mark Piechowski
I pulled the extension housing and che3cked the govenor and it was installed properly. The TV cable has no slack ans returns fully to the rear at idle. The govenor does have some deformation where the ball rests in the groove. I'm not sure if the play is enough to keep it from shifting. The mechanical aspects of the gov are ok, it seems to move smooth. I guess I will pull the valve body and check the spool valves there. I only inspected them for contamination. Anything I should look for?

Brian
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Mark
Mark

March 22nd, 2005, 2:12 am #5

Remove the govenor and put some compressed air into either of the holes. The govenor feed to the valve body will cause the shift valves to move. This way before you pull the vale body, you can see the shift valves move. If you only have first and second, did you install the direct shaft? Did the direct drum air check?

Mark Piechowski
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Joined: November 18th, 2004, 4:20 am

March 22nd, 2005, 3:08 am #6

I have a 90 f150 with AOD and after pricing tranmission repair I decided to tackle the rebuild by myself. If I pay myself $200 a day for three days and buy parts I do a little better than break even and learn some things.
I completed the rebuild and at present I have reverse and 1st. The transmission will not come out of 1st, and I fear the 2 mile trip around the block may have not been so wise. I have a couple of things I am uncertain about.
The governor had some rotational movement on the shaft, may be 10 degrees. Is this right? I remember it being a bear to slide off. I do have the ball in it. I am sure it's not backwards.
The TV lever arm on the transmission seems to float in the middle of it's range of movement, is that right?
The 2-3 accumulator piston has a pretty stiff spring and I can't see how such a loose fitting piston with these teflon seals could have enough buildup in pressure to actuate the piston with no blow by. I assumed it worked when I took it down.
I had all the pistons installed at the transmission shop, I did ruin one seal installing it without the guides. Any suggestions or comments are appreciated.
Did you compare the separator plate gasket?
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mpyrol
mpyrol

March 25th, 2005, 2:07 am #7

Remove the govenor and put some compressed air into either of the holes. The govenor feed to the valve body will cause the shift valves to move. This way before you pull the vale body, you can see the shift valves move. If you only have first and second, did you install the direct shaft? Did the direct drum air check?

Mark Piechowski
I got it working. I did check the direct clutch and the seperator plate gasket was the correct one. I removed the valve body and spool valves and checked for contamination, I found nothing. I did upgrade the accumulator to the dual o-ring one. From an engineering perspective this revised part is a substantial change from the original. I'm not sure if the better accumulator made the difference or if a more intense valve body cleaning did the trick. If I had to make a guess and even though I found nothing suspect the odds are the valvebody had an issue. It appears the accumulator is just a damper for the impulse in fluid pressure from the shift valve. In either case this forum was very helpful. I am happy to be get my old work truck on the road.

One more question; The parts guys at the tranny shop told me I didn't need to replace the steel plates if the were not burned. I did replace the burned ones in this tranny. Should all the steel plates be replaced or is that overkill? I mean if you don't resurface a manual pressure plate it fails very soon even if it's hand sanded.


Thanks Mark and Stuart

Brian

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Joined: November 18th, 2004, 4:20 am

March 25th, 2005, 4:39 am #8

My money would be on the valve body.
As for the steels.
For the cost, I replace them.
You can't see under the metal if someone else had a problem.
At the very least I scuff them up a bit.
On some newer transmissions they must have a very very shiny surface.
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brian
brian

September 6th, 2005, 6:28 pm #9

I have a 90 f150 with AOD and after pricing tranmission repair I decided to tackle the rebuild by myself. If I pay myself $200 a day for three days and buy parts I do a little better than break even and learn some things.
I completed the rebuild and at present I have reverse and 1st. The transmission will not come out of 1st, and I fear the 2 mile trip around the block may have not been so wise. I have a couple of things I am uncertain about.
The governor had some rotational movement on the shaft, may be 10 degrees. Is this right? I remember it being a bear to slide off. I do have the ball in it. I am sure it's not backwards.
The TV lever arm on the transmission seems to float in the middle of it's range of movement, is that right?
The 2-3 accumulator piston has a pretty stiff spring and I can't see how such a loose fitting piston with these teflon seals could have enough buildup in pressure to actuate the piston with no blow by. I assumed it worked when I took it down.
I had all the pistons installed at the transmission shop, I did ruin one seal installing it without the guides. Any suggestions or comments are appreciated.
wondering if you could give me any pointers on how to remove my selector arm on my tranmission so i can change the seal can't seem to pry it off without bending the arm it is a ford truck aod tranny 1990 and where i could buy a new seal thanks for your time
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Joined: November 18th, 2004, 4:20 am

September 6th, 2005, 8:14 pm #10

Remove the pan and valve body.
Remove the nut from inside the transmission holding the rooster comb.
There is a small roll pin that must be rmpved as well.
Look up into the case in line with the shaft.
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