another question on 881 sos

Brian J in MN · Apr 23, 2016

When shifting from 4th to 5th and from 5th to 4th even using the inching pedal, there is a noticeable jerk(like a slight lockup on tranny). Can this be caused by the spring loaded check balls in the servo interlock being weak or bad seating area for check balls?

This tractor has always done this. My dad purchased it used back in '61. It's a 1960 and it had a lot of tranny problems(previous owner abused it and was NOT clean with tranny oil) filter was not put in until after my dad purchased it.

Destroked 450 · Apr 23, 2016

Not sure about the servo interlock, it is a timing issue with the #2 and #3 bands that most all sos trans have. I've only driven half a dozen sos but they all but one had this slight jerk and the one that didn't had a slight skip like going into neutral for a moment.
During 4-5 up shift or 5-4 down shift the #2 and #3 bands are applying and releasing at the same time, if one of the bands applies faster than the other releases you get a momentary jerk like putting the trans in park for a second because that's what it's doing. #2 and #3 bands are spring applied and hydraulic released, park is when both bands are applied at the same time.
My 4000 jerked, my brothers 671 jerks and when I get the 881 I just bought running I'm sure it'll jerk too, I try not to do a 4-5 or 5-4 shift as much has I can and only then at reduced throttle.

Larry NCKS · Apr 23, 2016

Destroked's argument may have a little merit. However the main reason for the lurch between 4-5 and 5-4 is the number of components that shift in those changes.

When you shift 1-2 you change only one component; from clutch 3 to clutch 2 The same applies to shifts 3-4, 5-6 and 7-8.

When you shift 2-3, 6-7 the same thing happens in reverse, plus you shift from ORC or DDC (whichever applies to your tractor) to B1. In other words, you change two components in those shifts.

When you shift 4-5, you are changing three components at once; B1-ORC or DDC, B3-B2 and C2-c3. That's every component that makes that tractor operate in those ratios. Therefore the extra harshness there.

Even the newer tractors will do that. My Genesis tractors have that effect when they change from F1 to F2 directional clutch or vice versa because they are also shifting both other clutches that make that ratio function at the same time.

Brian J in MN · Apr 23, 2016

Thanks for the input Destroked and Larry.

I just wasn't sure if it was just the number of components changing or not during the shifting.

Brian

another question on 881 sos

Brian J in MN

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Destroked 450

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Larry NCKS

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Brian J in MN

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