Ford 871 sos shifting problems

[Using fords]

A couple of years ago I bought an Ford 871 sos. It had some trouble going into park, 5th, 6th, and 9th but if you shifted it a couple of times it would go in. Then a few weeks ago I was pulling hard( mostly in 5th gear) and it was operating as usual. The next time I used it the transmission seemed to be dragging slightly in r1 r2 1 2 3 4 9 and 10. I adjusted the trans, and changed the oil and that didn't help. In 1-4 and both reverse when you press the inching pedal it aggressively jerks to a stop (like going into park) and all other gears roll fine. I did pressure checks and will attach an image of the paper. The 100/0 in the park row means when first started it's 0 but when going from pressure in that servo to park you get 100 psi. The 100/0 in servo 3 in gears 1-4 means if I go from any pressurized gear direct to those gears it reads 100 and then slowly seeps down to zero. If I go into one of those gears and let it seep down and then shift to another one of them it stays at zero. Any help or pointers for what look for would be greatly appreciated

 

[Bern]

A couple of years ago I bought an Ford 871 sos. It had some trouble going into park, 5th, 6th, and 9th but if you shifted it a couple of times it would go in. Then a few weeks ago I was pulling hard( mostly in 5th gear) and it was operating as usual. The next time I used it the transmission seemed to be dragging slightly in r1 r2 1 2 3 4 9 and 10. I adjusted the trans, and changed the oil and that didn't help. In 1-4 and both reverse when you press the inching pedal it aggressively jerks to a stop (like going into park) and all other gears roll fine. I did pressure checks and will attach an image of the paper. The 100/0 in the park row means when first started it's 0 but when going from pressure in that servo to park you get 100 psi. The 100/0 in servo 3 in gears 1-4 means if I go from any pressurized gear direct to those gears it reads 100 and then slowly seeps down to zero. If I go into one of those gears and let it seep down and then shift to another one of them it stays at zero. Any help or pointers for what look for would be greatly appreciated View attachment 113529View attachment 113530

From reading your narrative, it sounds like the biggest problem came after you adjusted the bands - I'm guessing something went wrong with that process. I would carefully read the band adjustment instructions again and give it another go before you do anything else.

 

[Using fords]

It had the issues before I adjusted it. The adjustment didn't change much but it did seem to shift smother in 5-8 afterwards.

 

[ole fred]

50 years ago when I worked on the SOS's and the Ford dealer, it was almost always dirt. Your 871 is before they put a good filter in the system.
Sometimes, you can just take the valve body out and clean it up and make it work ------ for a while. Hours? Weeks" Eventually though, the dirt has to come out.
Of course, that was 50 years ago and I'm sure the problem is worse today.;

 

[Using fords]

Thanks Fred. I may end up just taking it apart and giving it a good cleaning and hope that helps.