Have a 86 F150 4x4 with a AOD. The transmission has about 30,000 miles on rebuild. Foward speeds work fine. Reverse slips when hot. Works fine when cold. I am thinking maybe a seal is leaking. I was in mud turning the pickup around in a tight spot and was shifting from foward to reverse many times when it broke.

Can anyone give me some ideas of what I need to look for to fix this?

TIA!

 

There's a chance it's something fairly simple. Just a chance, mind you, and it certainly could be something else. But...
I had this problem recently on my wife's car. Would backup fairly well on level ground, but not on any kind of hill at all. The problem was much worse when the car was up to temperature.
Got into it and found the seal on the reverse servo had a chunk out of it's seal. The seal was rock hard. Talked to a friend that owns a tranny shop and he said this wasn't uncommon. It's quite usual for the reverse servo seal to get very hard while the rest are fine. I had my doubts but replacing the servo worked and the car is driving just fine.
If you choose to try fixing it yourself, it's not too hard. Drop the pan and filter. Look carefully at how the linkage is connected and pull the valve body. It's difficult to do this without cracking or tearing the upper valve body gasket so plan for a new one. Once that's off you can get the servo out by removing a snap ring.
Best to get a manual something like this http://www.bulkpart.com/cgi-bin/miva...ory_Code=AODtm
The parts you need are here http://www.bulkpart.com/cgi-bin/miva...ory_Code=AODhp
part number 27952 or 27953. There are "grooves" on the servo shaft which indicate the length of the shaft. They are NOT interchangeable. You MUST know which one you need. The only way to be sure is to pull yours and look. There is a cover/seal for the servo which should also be replaced. It's cheap enough, check part number 27954.
Not a very difficult job, best to have that manual though. If your servo should prove to be OK, the manual will give you some ideas of what it might be. Should it be a reverse band or something, then you will have wasted your time, money , and about 12 quarts of ATF.
Up to you if you should decide to take a shot at it. This fix did work for me and a good tranny shop didn't find it at all unusual so it's possible it might help you. Only hands-on testing and diagnosis can really say for sure. Good luck!

 

Thanks for the info! That is what I was wondering if it could possible be something I could check with the pan off. I will give it a try.

Thanks