JD 850 (Yanmar) Internal Clutch Linkage Issue

Niji · Jun 20, 2024

I was working my farm road on a hill the other day and I pushed in the clutch to let my tractor roll freely backwards. I heard a pop and the clutch disengaged. The exterior linkage to the clutch pedal is fine, so whatever went is inside the bell housing. The clutch presses and releases normally but does not disengage the clutch. I had the transmission in low reverse and so I just drove it backwards to the house and killed the engine.

Reviewing the shop manual and a couple of videos online, I see there is very little in there that could go wrong, so I am curious just what this could be? There has never been any slippage or weirdness with the clutch, so I am pretty certain this has to be the internal mechanisms to the throwout bearing. Could this be caused by both release springs breaking? Well, no not that bacause the retraction and release tension on the clutch remains normal and I think those springs are responsible for that. So, is there some pin that might have sheared that holds the throwout bearing fork piece to the shaft coming from the clutch pedal linkage? There's just not that much to it, and I'm not really clear on just how this could be.

Thanks!

Harry in Ky · Jun 20, 2024

I would suspect something gave up on one of the release levers on the pressure plate. You'll find out when you split it.

winston1 · Jun 20, 2024

I think a split is inevitable.

Niji · Jun 20, 2024

Yeah, that's what I was figuring. Splitting, here we come!

bmaverick · Jun 20, 2024

Niji said:
Yeah, that's what I was figuring. Splitting, here we come!

The Hoye video is helpful, however, you will need to DRAIN the hydraulic fluid to split the tractor. Or be very very very fast at plugging the suction pipe under the right side foot rest when you take the rubber hose jumper off.

I would drain the fluid. If you did a fluid change not long ago, then SAVE the fluid. You can filter it, then put back into the JD850.

ONLY use JDM J20C in our machines aka Hy-Gard or Yanmar TF500A. You can use store brand licensed J20C as well. it must state 'meets' and never compatible with.

Niji · Jun 20, 2024

Thanks for the info BMaverick. I've gotten a lot of parts from Hoye over the years and I came up with that video yesterday and gave it a look. I also found one on Youtube of a guy splitting a JD 950. And I will take your advice on the hydraulic oil. I hope to begin the great undoing tomorrow and get down to splitting in the next couple of days.

bmaverick · Jun 21, 2024

Niji said:
Thanks for the info BMaverick. I've gotten a lot of parts from Hoye over the years and I came up with that video yesterday and gave it a look. I also found one on Youtube of a guy splitting a JD 950. And I will take your advice on the hydraulic oil. I hope to begin the great undoing tomorrow and get down to splitting in the next couple of days.

If you get stuck at any point, jump on here and ask right away. Someone might be here to response.

Niji · Jun 21, 2024

Hey hay! The FEL is off--first time ever. That's a start!

Niji · Jun 23, 2024

Got the JD 850 split today--it was a WAY easier job than I thought it would be. Very straightfoward. And when I got in there, one spring had come off the gizmo holding the throwout bearing that is attached to the clutch pedal linkage, and one surface of clutch pad had crumbled into oblivian, but I got lucky and all of my rotor surfaces came through unscathed! It seems that this is the original clutch and that the tractor had never been split before--so hey, put in a new clutch and call it good for another 40 years! Ordering parts tomorrow morning, and I think this should be just a regular clutch job at this point.

bmaverick · Jun 23, 2024

Niji said:
Got the JD 850 split today--it was a WAY easier job than I thought it would be. Very straightforward. And when I got in there, one spring had come off the gizmo holding the throw-out bearing that is attached to the clutch pedal linkage, and one surface of clutch pad had crumbled into oblivion, but I got lucky and all of my rotor surfaces came through unscathed! It seems that this is the original clutch and that the tractor had never been split before--so hey, put in a new clutch and call it good for another 40 years! Ordering parts tomorrow morning, and I think this should be just a regular clutch job at this point.

Ah, so happy for you.

A new clutch, some cleaning and bolt everything back together.

Fredricks