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  1. #1
    Platinum Member
    Join Date
    Apr 2002
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    556
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    SE Minnesota
    Tractor
    John Deere 4720 Cab

    Default John Deere F725 Hydraulic lift modifications

    I recently purchased a used F725 front mount mower. These are nice mowers, I owned one ten years ago, but the hydraulic lift feature isn't what it should be. You can lift the mower with the hydraulic control but you have to hold it up to keep the mower suspended. As soon as you let go the mower gently drops to the ground.

    The F735 diesel has a different hydraulic control which keeps the mower suspended. It functions similar to the F900 series front mount mowers.
    I suppose it was an issue of the extra weight of the diesel engine offsetting the weight of the mower.

    Since you can put a 60" mower on a F735 and I have a 48" mower on the F725 I would think there would be enough weight to keep the rear of the tractor on the ground.

    I would like to modify the 725 hydraulics to work similar to the 735. The JDparts website shows a different control valve but I suspect it quite costly.

    Any suggestions on how to do what I want without breaking the budget?

  2. #2
    Elite Member zzvyb6's Avatar
    Join Date
    Dec 2006
    Posts
    2,740
    Location
    michigan
    Tractor
    jd 1070

    Default Re: John Deere F725 Hydraulic lift modifications

    I just picked up a used older F935 mower which did the same thing. On mine, there is a "weight transfer" valve you can adjust to set the balance of the front deck. Its on the control panel on the right side. Perhaps you can investigate some adjustment on the pressure relief setting on your mower.

    Otherwise, it sounds like there is a leaky seal in the hydraulic control valve. New seal = no drift.

    If nothing else is possible, these mowers were equipped with optional auxilliary hydraulic circuits to swing a plow or broom. Perhaps you could tap into that circuit and run the mower lift arms from it instead of the originally designed circuit.

    BTWL there is enough motor in these to easily run the 72" decks. I have a spare MMM from my 1070 that could use a new home.... Same driveline and configuration. Would need to have the 700/900 mounts welded on.
    There is no "I" in team, but there is a "Me" if you want to jumble it up a bit...

  3. #3
    Bronze Member
    Join Date
    Dec 2006
    Posts
    94

    Default Re: John Deere F725 Hydraulic lift modifications

    I actually know quite a bit about these, so I'll chime in. the F700's are vastly different from F900's. The F725 is not designed to hold the deck up for stability reasons. The F725 has an integrated weight transfer valve included in the valve (turn it R/L to adjust).

    I'd advise against trying to modify the lift system. The current system lifts the deck by blocking the pump flow, which then backs up to the lift cylinder and raises the deck. If you install some type of valve to hold the deck in this position, you will be causing all the pump oil to bypass through the relief valve, thus overheating the system.

    But I know, it is aggrevating to have to drive everywhere with the deck down and getting beat around!

    Hope this helps!

  4. #4
    Platinum Member
    Join Date
    Apr 2002
    Posts
    556
    Location
    SE Minnesota
    Tractor
    John Deere 4720 Cab

    Default Re: John Deere F725 Hydraulic lift modifications

    Engine Tech, thanks for the reply. I suspect I will just leave it alone but your right, it is a little annoying.

    Do you by chance know how the hydraulics are different on the F735 diesel? I know it uses more of a standard type of hydraulic control. I understand you can keep the deck in the lifted position. I was just hoping to be able to adapt the 735 system on my 725.

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