ford 871D Sos problems

goat farmer

New User
Hello I'm having trouble with my just purchased 1959 Ford 871 . Gears 5 through 8 give a slight jerk and then don't work .9th engages for a few seconds then releases .10th works. It goes to neutral in park . Any body have any suggestions? Thanks .
 
The ford SOS trans was ahead of their time when first introduced, when they were working. Dad bought a new 901 I would say about 1959 or 60. It was in the shop more than we could use it for trans problems, many just the same as you're describing. We finally traded it off so we had something to farm with. Good luck.
 
(quoted from post at 21:25:45 01/27/18) Hello I'm having trouble with my just purchased 1959 Ford 871 . Gears 5 through 8 give a slight jerk and then don't work .9th engages for a few seconds then releases .10th works. It goes to neutral in park . Any body have any suggestions? Thanks .

You don't mention 1st through 4th or R1 & R2, so I assume that those are all working properly?
 
(quoted from post at 21:26:28 01/27/18) I've adjusted the bands a couple times . Didn't seem to help .

3 questions.

1. Which transmission do you have? If it is the original "red" transmission it will have a raised 312259 cast on the left side of the case. If it has been upgraded to the later version "blue" transmission that raised cast number will be C3NN-7006-B.

2. When adjusting bands did all 3 of them torque down as expected?

3. Did you have an SOS band adjustment manual that was correct for the transmission you tractor has?
 
It's got the 259 transmission. I think my manual is right for band 1 it says to tighten to 20 lb ft and back off 3/4 turn . 2 and 3 were tighten to 5 to 10 lb ft and back off 1 turn. Everything torqued down correctly.
 

My manual says 5-10 ft. lb. torque on all three bands.
Band 1 backed off 1 turn
Bands 2,3 backed off 3/4 turn

Just to confirm your are making the band adjustments with the traction coupling disconnected, engine running and oil warmed up, transmission shifter to the proper gear for each adjustment?

Adjust band 1,2 with engine running, transmission in neutral
Adjust band 3 with engine running ,transmission in 5th gear

This is according to my manual which is a reprint of the 1961 service manual.
 
I'm still hung up on the fact that it goes to neutral in park. Something is amiss with bands 2&3 for that to be the issue. The next question
would be, does it park (hold the tractor on a hill) with the engine off? If not, focus on bands 2&3 - they are what give you park.

Either you have a broken band, or else when you adjusted it the pressure was so low that the adjustment was incorrect. Take a look at how
many threads of the adjusting screw are sticking out past the nut. They should be similar to each other.
 
(quoted from post at 10:00:54 01/28/18) I'm still hung up on the fact that it goes to neutral in park. Something is amiss with bands 2&3 for that to be the issue. The next question
would be, does it park (hold the tractor on a hill) with the engine off? If not, focus on bands 2&3 - they are what give you park.

Either you have a broken band, or else when you adjusted it the pressure was so low that the adjustment was incorrect. Take a look at how
many threads of the adjusting screw are sticking out past the nut. They should be similar to each other.
he adjusting screws aren't same far out. How can I know if something is wrong with the bands ?
 
(quoted from post at 13:22:16 01/28/18) with the engine off it rolls like it would be in neutral.

Have you reconnected your traction disconnect and it still rolls in Park with engine off?
 
Re-adjust #2&3 bands by the book. If they don't feel the same, one of them is faulty. #2 band can be viewed through the steering box hole, #3
band can be somewhat seen after removing the top cover and control valve. That said, a split would be required to replace either.
 
I've also tried adjusting it by a method that I found on here somewhere . I think it was posted by Zane .
How precise are these adjustments ? Wil a small amount make a big difference?
 
(quoted from post at 15:10:13 01/28/18)
(quoted from post at 16:29:14 01/28/18) How precise are these adjustments ? Wil a small amount make a big difference?

Define "small amount".
Like 18 turn. Band 2 is very questionable I think. Seems like it doesn't go in as far as the other 2.
 
As I said earlier, if bands 2 & 3 don't feel pretty much identical with regards to the adjustment process, along with the ultimate position
of the number of threads after the fact, something is wrong internally. That you say it rolls with the engine off pretty much confirms the
problem.

Either something is wrong internally, OR you screwed up (pardon the pun) the adjustment process, OR the internal pressures are too low to get
an accurate adjustment.
 
(quoted from post at 16:32:23 01/28/18) As I said earlier, if bands 2 & 3 don't feel pretty much identical with regards to the adjustment process, along with the ultimate position
of the number of threads after the fact, something is wrong internally. That you say it rolls with the engine off pretty much confirms the
problem.

Either something is wrong internally, OR you screwed up (pardon the pun) the adjustment process, OR the internal pressures are too low to get
an accurate adjustment.
hat do you mean by internal pressure being too low ? I'm guessing I should probably find a pressure guage to check all of that.
 
If you have an issue with low pressure, the bands will not fully release (check out my video in the thread below titled "SOS pressure
testing"). If the band does not fully release when doing the adjustment (remember, the engine has to be running), your adjustment may or may
not be accurate.

Low pressure could be caused by any number of things - plugged screen, worn pump, blown seals, cracked pressure pipe(s), the list goes on and
on. Your service manual details how to check pressures.
 
(quoted from post at 17:40:20 01/28/18) If you have an issue with low pressure, the bands will not fully release (check out my video in the thread below titled "SOS pressure
testing"). If the band does not fully release when doing the adjustment (remember, the engine has to be running), your adjustment may or may
not be accurate.

Low pressure could be caused by any number of things - plugged screen, worn pump, blown seals, cracked pressure pipe(s), the list goes on and
on. Your service manual details how to check pressures.
k. I'll check that out . Do you know offhand what size fitting it takes to hook up to pressure test ?
 
Ok . I've still not got it figured out. Now when I shift down to 8 from 9 it seems like it's trying to go but something is tight ?? It does that for 5 6 7 gears as well .
 
(quoted from post at 16:31:22 02/14/18) Ok . I've still not got it figured out. Now when I shift down to 8 from 9 it seems like it's trying to go but something is tight ?? It does that for 5 6 7 gears as well .

The common element that would make 5,6,7 & 8 "seem tight" is band 3. I'd suggest you don't have it adjusted quite correctly. What you're saying makes it sound tight, or not backing off far enough. My guess is that as much as you've played with band adjustment, you just need to get that correct.

Band 3 on the overrunning clutch (red or in most cases 312259) transmission is engine running 800 RPM, transmission at normal operating temperature, traction disconnect disengaged, wheels blocked, transmission in 5th gear, torque 5 to 10 foot pounds, back off 3/4 of a turn. Make sure you hold the band adjustment screw exactly there while you re-torque the lock nut.

While you're at it, if you haven't already done so, check the hydraulic pressure at band 3. If it's not up to snuff, that may be causing part of your problem as well, but certainly would not result in the transmission going to neutral in park.
 
(quoted from post at 16:30:49 02/14/18)
(quoted from post at 16:31:22 02/14/18) Ok . I've still not got it figured out. Now when I shift down to 8 from 9 it seems like it's trying to go but something is tight ?? It does that for 5 6 7 gears as well .

The common element that would make 5,6,7 & 8 "seem tight" is band 3. I'd suggest you don't have it adjusted quite correctly. What you're saying makes it sound tight, or not backing off far enough. My guess is that as much as you've played with band adjustment, you just need to get that correct.

Band 3 on the overrunning clutch (red or in most cases 312259) transmission is engine running 800 RPM, transmission at normal operating temperature, traction disconnect disengaged, wheels blocked, transmission in 5th gear, torque 5 to 10 foot pounds, back off 3/4 of a turn. Make sure you hold the band adjustment screw exactly there while you re-torque the lock nut.

While you're at it, if you haven't already done so, check the hydraulic pressure at band 3. If it's not up to snuff, that may be causing part of your problem as well, but certainly would not result in the transmission going to neutral in park.
it feels like it's going in to park when I down shift to those gears . It doesn't do that if I go from 4 to 5 or shifting up in to other gears . Only when I'm shifting down. I'm extremely confused right now . Lol .
 

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