JD F935 coupler replacement

Discussion in 'Mechanic and Repair' started by Mr.Ziffel, Jun 4, 2001.

  1. Mr.Ziffel

    Mr.Ziffel LawnSite Senior Member
    Messages: 291

    A guy was demonstrating my f935 front mower as he wants to buy it, cutting along fine when it just stopped. The rubber coupler between the engine shaft and hydro drive had disintegrated. I used this mower for two full seasons with no problems. [I went to 60" Exmark Lazer for better quality cut]. I was right there when it happened and although he was mowing tall grass and cutting it pretty short, it didn't seem to me that anything unusual happened or that he did anything wrong--the thing just stopped.

    I picked up a replacement coupler from dealer [$80! and no aftermarket available] and it appears easy to replace but I'd like to know why it went bad. The machine had not been run since a year ago October, stored in dry shop. He engaged pto at 1/2 throttle, revved to full throttle and was cutting along fine when it broke. It did seem that one of the six bolts through the coupler was a bit loose so I'll be sure that they're all tight when I replace it.

    Does anyone have any tips or hints to make sure it's set up right before I turn it on again? How about on aligning the two shafts. Any ideas? The guy really wants this mower and I really want to sell it to him, but we both want to make sure it's right before we proceed. Any help appreciated. Thanks, Will M>
  2. Highpoint

    Highpoint LawnSite Member
    Messages: 153

    I used to run JD935s. This happened several times. As to WHY this happened, considering the amount if time in storage, I'd say dry rot got to it. No worries though, simple to replace and should last a long time for the new owner. There is no ryme or reason in trying to align the new one. It is supposed to be cattywhompus. It flexes with the motor since it is on rubber mounts and the hydro is mounted solid. As you said, be sure the bolts are tight. Good luck.
  3. Mr.Ziffel

    Mr.Ziffel LawnSite Senior Member
    Messages: 291

    Thanks for the reply. I'm going to wait until the guy comes over again later this week and replace it in front of him so he can see how easy it is. Any other suggestions from anyone with experience? Thanks again. Will M>
  4. TLS

    TLS LawnSite Fanatic
    Messages: 7,943

    Mr. Ziffel,

    Sorry, I didn't even know that this forum was here! Well, I had it happen once and replaced mine twice. The first time it just broke like yours did. The second one was replaced the year I sold it. Highpoint explained it right. Not using it may be the major cause. However, it may be accellerated by the motor mounts "settling" down a bit and making this piece of rubber more of a universal joint than a coupler! Speaking of Universal joints! Went through a few of them too!!

    My electric $245.00 PTO clutch went KAPLOEY when the new owner was demoing it in my yard! These 935's just dont want to be sold!!!

    Good luck.
  5. rballardvt

    rballardvt LawnSite Member
    from Vermont
    Messages: 3

    I have a JD f915, similar to yours and has the same coupler which has also gone twice in the last 3 years. But only once in the 7 years before that. The one on it now has a small crack in it. I have heard they can go easy but I also heard the engine mount theory. I'm going to check that out since I rebuilt the engine in the thing 3 years ago. I'm also having a problem with the gear box on the 60 inch deck blowing out. If anyone has any ideas on that, I'd appreciate it.

  6. TLS

    TLS LawnSite Fanatic
    Messages: 7,943

    What do you mean by "blowing out"? I had a couple thousand hours on a 60" front mount deck and never had any gear box issues, come to think of it, only changed the oil in it once! What exactly is your problem. From the sounds of it, you must have a 5000+ hr machine on your hands! Time to sell!

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