F935 forward/reverse/neutral linkage and lift power

wantmoore · Jul 15, 2015

Recently picked up a later model F935 that had been sitting unused/neglected in our rough northern winters for a few years. I've resolved most of it's issues, but two remain.

1) The forward/reverse linkage has no "return to neutral" ability. While moving forward, the only way to get back to neutral is to press the reverse pedal until I find the neutral spot. Reverse is the same - I have to press the forward pedal to move the linkage back to neutral. This has a tendency to be a little dangerous given the F-series weight distribution. :laughing: I have PDFs of the tech manuals and even have access to a well-functioning F935 at my place of employment for comparison, but I just can't find the root cause here and it's driving me crazy. All the springs appear to be connected properly and there are no obvious points of "stickyness" that need greasing.

2) The deck lift isn't functioning as it should. I've changed replaced filter and fluid with new HyGard and been through most of the components of the deck lift. New (to me) weight transfer valve, control valve inspected, and lift cylinders were leak tested per the tech manual and checked out to the best of my ability. Here's where it gets fun... At initial startup, if I quickly go to full/wide-open throttle and move the control lever to the lift position, the lift works like a champ. After a few minutes, I lower it and attempt to lift again and it does nothing.

Thoughts?

zzvyb6 · Jul 15, 2015

Welcome to the forum.
Tech manual says:
Check for dented or restricted line.
Test charge pump pressure.
Check for plugged hydraulic filter. (This could even be a braqnd new one because of what got freed up after the first change).
Check suction line for air leaks.
Test relief valve pressure.
inspect cylinder packings for excessive wear. (I.E> if one of the lift cylinders is bad, both will not work properly)

I also suggest you check the load transfer valve. When you open the valve it picks up the deck to add the deck weight to the front wheels. This helps on hill climbing, etc.

Keep checking the sight glass for proper oil level. Its a one inch long glass tube in the middle of a rubber hose line right near the deck drive shaft location.

The pedal problem is common: lack of lube and some weak springs. Note that it has to be about in the neutral position in order to start.

Keep looking. Let us all know what you find.

wantmoore · Jul 16, 2015

zzvyb6 said:
The pedal problem is common: lack of lube and some weak springs. Note that it has to be about in the neutral position in order to start.

Is the spring mainly responsible for neutral-return the one connected to the rod that comes up behind the seat platform? I know that's the neutral-adjustment, but not sure if there is another adding return pressure.

wantmoore · Jul 20, 2015

Took most of the linkage apart this weekend until I found the sticky pivot point. It was the pie-shaped pivot piece that the cruise gear locks into - item 8B & 22 in the parts catalog pic. I have a later model ('96) machine, so no bushing, just the part that slides on the shaft which is a fabricated part of the frame. Took a lot of PBBlaster, some emery paper and elbow grease to get it off and then more of that to get the surfaces polished, but it's super smooth and working great now!

wateka · Sep 7, 2015

This thread saved my bacon. I bought a used F935 and it had pedals that required serious leg muscle to go forwards or backwards. I thought the tranny was shot, but it turned out to be the before mentioned pie shaped piece that had rusted/corroded onto the shaft. Pictures below. I had to let the piece sit overnight after soaking it with Blaster and then was able to hammer it off with a screwdriver. Pictures below for reference. Once the pie shaped piece was off, wrap a piece of fine sandpaper around your finger and spin the pie shaped piece around your finger (and the sandpaper) to clean it up and it works perfectly now.

beenthere · Sep 7, 2015

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