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Discussion Starter #1
Thought I would share this.

JD 650. Going from gear to gear was fine, but after starting in neutral I was grinding just to get it into gear. Time to replace the clutch.

Splitting the tractor was not hard at all. Luckily for me instead of removing the engine with the front end, I opted for removing the front end and then taking the engine out with a crane.

Used a cold chisel to start the separation, but the most I could get between the engine and bell housing was about a half inch. No amount of jerking, pulling, or prying (and I used a 6 foot piece of pipe as a lever at one point) could get much more than another 1/4 inch. It was stuck fast. Damn!

After thinking about it for a while, I went to Runnings and got a large sample of M10 Bolts with the longest thread (x1.75 I think) they had, some M10 threaded rod and M10 nuts. The plan was to use them as a makeshift "press" to force the engine off while keeping everything aligned.

I started by rotating the engine a few degrees so the mounting holes didn't line up any more and then threading 3 of the long bolts through from the engine side so they could push against the transmission housing (they would normally be inserted from the bell housing side). I wanted to use 4, but the left side of the engine has no holes near the top that are accessible to thread a bolt in from the front. If I got desperate, I was going to remove one of the starter mounting studs and use that threaded hole.

Taking care to screw them in evenly a bit at a time and whacking the top left of the engine with a hammer occasionally to keep that portion in line, I reached the limit of the bolts (they were threaded all the way in). At this point I was going to resort to the threaded rod with a nut between the engine and transmission to do the pushing, but as I tightened the last bolt to its limit there was a satisfying loud "pop" and the engine was free.

When I unbolted the pressure plate, the friction material with it's backing plate fell out. Just the outer part of the clutch plate. The center portion of the clutch plate was cupped and wedged into the pressure plate so tight I could not budge it with a hammer. What had apparently happened was that the clutch plate had seized onto the first motion shaft preventing me from extracting the engine and probably explaining why the gears were grinding going from neutral with the clutch engaged to clutch disengaged and shifting to any gear.

Al
 

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Thought I would share this.

JD 650. Going from gear to gear was fine, but after starting in neutral I was grinding just to get it into gear. Time to replace the clutch.

Splitting the tractor was not hard at all. Luckily for me instead of removing the engine with the front end, I opted for removing the front end and then taking the engine out with a crane.

Used a cold chisel to start the separation, but the most I could get between the engine and bell housing was about a half inch. No amount of jerking, pulling, or prying (and I used a 6 foot piece of pipe as a lever at one point) could get much more than another 1/4 inch. It was stuck fast. Damn!

After thinking about it for a while, I went to Runnings and got a large sample of M10 Bolts with the longest thread (x1.75 I think) they had, some M10 threaded rod and M10 nuts. The plan was to use them as a makeshift "press" to force the engine off while keeping everything aligned.

I started by rotating the engine a few degrees so the mounting holes didn't line up any more and then threading 3 of the long bolts through from the engine side so they could push against the transmission housing (they would normally be inserted from the bell housing side). I wanted to use 4, but the left side of the engine has no holes near the top that are accessible to thread a bolt in from the front. If I got desperate, I was going to remove one of the starter mounting studs and use that threaded hole.

Taking care<script id="gpt-impl-0.10896142250771695" src="https://securepubads.g.doubleclick.net/gpt/pubads_impl_110.js"></script> to screw them in evenly a bit at a time and whacking the top left of the engine with a hammer occasionally to keep that portion in line, I reached the limit of the bolts (they were threaded all the way in). At this point I was going to resort to the threaded rod with a nut between the engine and transmission to do the pushing, but as I tightened the last bolt to its limit there was a satisfying loud "pop" and the engine was free.

When I unbolted the pressure plate, the friction material with it's backing plate fell out. Just the outer part of the clutch plate. The center portion of the clutch plate was cupped and wedged into the pressure plate so tight I could not budge it with a hammer. What had apparently happened was that the clutch plate had seized onto the first motion shaft preventing me from extracting the engine and probably explaining why the gears were grinding going from neutral with the clutch engaged to clutch disengaged and shifting to any gear.

Al
Was it the OEM clutch parts? How many hours? I just replaced and clutch and pressure plate on a 650 that was behaving just like yours. The clutch disc did not separate but it seems to shift good with the new parts.
 

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Discussion Starter #3
I don't know anything about the history of the tractor. It has 2300 hours on it; 100 more than when I bought it last year.

The clutch did not look very worn. Now, if it had spent it's prior 2200 hours mowing roadsides, them maybe it wouldn't be worn much, but I suspect it was changed at least once in it's life.

The first motion shaft had a coating of rust which seemed to originate from the disk and not the shaft. The shaft will be properly lubricated when I reassemble this weekend to prevent it from happening again soon. Also noticed black oil drops from the weep hole in the bottom of the bell housing when operating. Based on the color I assume is must be from the engine so I had to wait while I ordered a new seal and O ring for the rear bearing holder.

Al
 

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I don't know anything about the history of the tractor. It has 2300 hours on it; 100 more than when I bought it last year.

The clutch did not look very worn. Now, if it had spent it's prior 2200 hours mowing roadsides, them maybe it wouldn't be worn much, but I suspect it was changed at least once in it's life.

The first motion shaft had a coating of rust which seemed to originate from the disk and not the shaft. The shaft will be properly lubricated when I reassemble this weekend to prevent it from happening again soon. Also noticed black oil drops from the weep hole in the bottom of the bell housing when operating. Based on the color I assume is must be from the engine so I had to wait while I ordered a new seal and O ring for the rear bearing holder.

Al
Thanks. I replaced that seal on mine too. Strange that neither of use could see much wear on the clutch disc but neither tractor shifted smoothly. Mine shifts much nicer with the new clutch.
 

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Discussion Starter #5
A follow up...

I put the tractor back together last weekend. After which, I could not get it into gear - like the clutch would not disengage. After many choice words I pushed the tractor over to my side of the garage (wife was happy about that part), cleaned up my tools and said f it for the winter.

After calming down, I wanted to figure out what was wrong. It had to be the release bearing not working, the first motion shaft seized into the pilot hole or the disc in backwards. Pulled it apart again (amazing how quickly I can separate it now that I know what I'm doing) this morning. The clutch disc does not look like the OEM part in the service manual but does look exactly like the one that was in the tractor. I had reassembled it just like the one I replaced - the "stepped out" part of the disc with the springs facing towards the transmission. I noticed that center of the disc seemed awfully close to the pressure plate fingers and that the release bearing might well be forcing it into the flywheel and thus keeping it spinning when the pedal was depressed. I flipped it around and remounted the engine. Put it in gear and held the clutch down. Spinning the engine did not turn the wheels. Success (I hope)!

So the answer to the question of why this was happening to begin with even though the disc seemed to have plenty of friction material left on it is probably answered. The last mechanic screwed up and I copied his mistake!

I'll finish the reassembly during the week and see if the problem is really solved when I have the engine running.

Al
 
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