Got a chance to check the hydro linkage on my new-to-me/used JD 317 that I acquired recently. It has a nasty habit of accelerating on its own in F or R under any amount of throttle...especially if going downhill or backwards up over a slight rise...like onto the concrete slab on the front porch/slab of my small shop.
Got the side panels off, battery and battery tray out and discovered after some poking around that all the front linkage is tight and that the dampener is smooth. I tightened the friction brake on the linkage a little, thinking maybe this was the root cause of the problem. Nope. Same behavior after this adjustment, although the shifter arm performed a little better...not as loose as before.
Then I got the free-wheeling knob, parking brake knob and deck height knob/nuts/pieces off the fender pan and pulled the fender pan off. The connection of the shifter linkage rod and control/swash plate on the hydro itself seemed a little loose, so I cleaned it off and got the pin out that holds these two together. Seems too short. And the cotter pin that holds the two together seems to be in the wrong spot...it joins one half of the yoke to the control/swash plate, but the cotter pin goes in between the swash/control plate and the second arm of the yoke. I expected the pin to go through both arms of the yoke, with the control/swash plate in between and the cotter pin on the outside of a yoke arm. See pix below.
The pin is JD part M46200 but the new online parts catalog doesn't list specs like dimensions (length/width/diameter, etc.) like the old catalog so I don't know if the pin shown below is correct. It is exactly 1" long and the cotter pin hole is about 5/8ths" in from the head.
I found a used linkage on the auction site (see pix) that seems to indicate I may have the right pin after all..but what do I know? Anyone know the specs on this part...ie, length/diameter? It is the same size/diameter as the pin that connects the lift arm to the yoke on the adjustable deck lift strap (which is too long to work in the limited space around the hydro linkage).
I put the shorter pin back in and took it for a spin around the yard. This time I noticed that the hydro sometimes slows way down and acts like the pump may be cavitating...it stutters/chatters unless you push the shift linkage further F or R. So maybe it just needs a fluid/filter change and maybe a good purge.
Found this link online about purging a hydro tranny:
Anyone ever purged a JD hydro in this fashion? If you use another method, please explain with a simple 1-2-3 list of steps.
Thanks in advance.
Gotta say I really like this 317...it may find a spot in my permanent herd if I can resolve the hydro speed & chatter/stutter problem. Note, it appears to have enough fluid in the sight glass...but you know PO's...what kind of fluid and when was the filter changed last? Will probably pull the fender pan to change the filter, as that is much easier than pulling the belly pan/screen off (nice and clean)...no need for that. Thanks for any and all input.