# Please help - Deere F935 - Very slow ground speed problem



## HDGMC11 (Jun 23, 2015)

I bought a John Deere F935 about a month ago from an older guy who owned and maintained it the previous 15 years. Has about 1,500 hours on it. Good condition, and when I test drove it everything seemed fine. EXCEPT, I didn't know how fast/slow it was supposed to go, and now I'm realizing how slow this thing really is. I'd bet I only get 4mph in forward and 1-2 mph reverse, when I should be getting 10mph. I feel like a could mow my grass faster than this thing. It feels like the power just isn't getting to the tires.

Any thoughts why it lacks ground speed?

Additional info that might help:
Mower deck doesn't stay lifted - it'll slowly creep down
Engine seems to run great and sounds like it's getting full RPMs
Throttle lever cable looks to engage all the way
Previous owner seemed to know everything about it and said he kept up with maintenance
Previous owner was mowing a pretty flat yard
It came with a snow blade that he put on every winter
Speed is same with mower engaged and disengaged

Thank you very much for your time.


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## BigT (Sep 15, 2014)

Howdy HDGMC11,

Welcome to the tractor forum.

I believe the F935 has a hydrostat transmission. Does it start out normal/fast and then slow down?? If so, pull the hydraulic dipstick and see if the fluid on the dipstick has tiny air bubbles entrained in it. If so, you have a suction leak. Find it and fix it. 

The hydraulic fluid should be clear, no milky appearance (water). My hydraulic fluid is so clear that I have trouble seeing it on the dipstick. If fluid is dirty or milky, change it. 

There should be a suction screen at the bottom of the hydraulic reservoir where the suction line attaches. Drain reservoir and clean screen.

There should be a hydraulic filter near the hydraulic pump or reservoir. Change the filter.

Perhaps the linkage from the foot pedal to the hydrostat needs adjusting to get more speed. Check it out.


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## HDGMC11 (Jun 23, 2015)

BigT said:


> Howdy HDGMC11,
> 
> Welcome to the tractor forum.
> 
> ...


Great info Big T, thanks for your advice. I'll check all those tonight when I get home.

To answer your question, it does not start out any faster or slower than the max speed it maintains after. In other words, it doesn't slow down, it just won't go any faster than 4mph at any point in time.

That ring any other bells?

Thank you again!


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## HDGMC11 (Jun 23, 2015)

Following up on this - I had some time to take a look at the mower again. Before diving into the transmission and more complicated stuff I ended up looking closer at my throttle and forward/reverse linkage. I found that my throttle cable wasn't pulling the lever all the way, so I adjusted the cable and was able to get the lever to max out, giving me a decent max RPM increase. I then looked at the forward/reverse linkage. It seemed correct, however, I noticed when I'd push the pedal the linkage back by the transmission was shifting sideways while moving the pedal forward, like there was something loose. Turns out, the (pinch style) bolt that clamps the linkage by the transmission was kind of lose, so I tightened it and got it tight enough so the linkage only moved forward and back and didn't shift sideways in the process.

After tightening up these two things, which would easily be attributed to just normal wear/losening over the years, I have gained a considerable amount of ground speed. Fast enough that I cannot mow full speed anymore.

Let's just say I'm not excited to mow the grass again.

Thanks again for your input, hopefully this helps anyone else running into this problem


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