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JD 647 tiller is a brute :)

15009 Views 14 Replies 9 Participants Last post by  dmay
I was tilling a part of my yard site and encountered numerous buried rocks of various sizes. The 647 tiller would just glang bang and cough them out. Then I encountered something that temporarily bogged the engine down then returned to normal. Curious I stopped to take a look and found a 2ft piece of rebar wrapped around the shaft. Took me a while with a crowbar to bend it in an orientation that allowed me to wrestle it off the shaft. Then back to tilling.

What a brute this tiller is. :thumbup1gif:
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As luck would have it, I had another opportunity to test the strength of my tiller against a piece of rebar. This time I took pics. Stopped the tractor dead in the field but after another successful removal operation we were back to tilling. I'm half way through tilling ~4.5 acres so far. I'll post pics of the tilled land when I'm done.


Yes it has a slip clutch but whenever I encounter something like this it does stop me cold. I might need to loosen the clutch bolts. Honestly I'm still awaiting my dealer to supply the manual for the unit.
On searching I found this on another forum,

"You should loosen it, but not right slack, and then run it in slip-mode (with light load) for 5-10 seconds (seems like a long time, but it's not), to have it seat itself, and work itself together.... You know if you accomplished it because it should get warm - to almost hot, but not burning your fingers, and definitely but don't burn the clutch up! If it doesn't heat up when you do that, tighten it up a tiny bit and re-run it... it needs to run under load, rubbing the plates together, to seat themselves properly. Once it breaks itself in, let it cool, adjust it by testing it out - if you see / hear it slip under normal load, tighten it by tightening each bolt by 1/4 turn. Run it again, and basically it should be on the border line of slipping under very heavy load (tractor engine bogs down). That way, you can till with max HP going to the ground, but as soon as the load surges above that, it will slip."

No pics to go along with the above. Does this sound like a good procedure to follow for a JD 647 tiller? Anyone got a 647 manual? Mine is on order and due to arrive next week.
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Here are pics of my tiller. Easy to adjust the 8 slip clutch nuts/bolts after you remove the cover plate. I had to remove the nuts/bolts/springs completely and one rubber mallet hit to make it come apart. Everything was lightly rusted stuck in place. Cleaned and reassembled nuts/bolts/springs hand tight. Was able to slip just by using my foot to turn a tiller blade. Tractor not running of course. Then proceeded out to the field and just did a process of incremental stop, tighten and test until I got the correct tension with tiller engaging and churning dirt.


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