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fpappal

725 Rear tires only spin in opposite directions.

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fpappal
Over the winter I rebuilt the transmission on my 725 because it was stuck in gear. I got that problem resolved and put it back on the tractor. The front tire was flat so I never tried moving it until a few days ago. Even though it is in neutral, the rear tires will not move forward or backwards. If I jack the back end up the tires will spin in opposite directions freely. They will not move in the same direction however. I am beyond discouraged at this point, this restoration has been one road block after another. The engine is off getting a new valve guide installed. If this is not an easy fix I will be looking to get rid of it. Any suggestions? Thanks.

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ReedS
My best guess is that your inner diff (axle) gear is not in the right place, one too many washers on one side or another. Very easy to do, did it myself not long ago. Gear is catching both sets of spur gears in diff. IIRC looking at diff, hub removed you should have the circlip, the circlip washer (has a step in it to fit circlip), washer,gear and one single thrust washer behind it. The oops that I did was to put 2 washers beind the gear therefore my gear was catching both sets of spur gears, result.... no diff action, tractor wanted to go in a straight line! Just my 2 cents value accordingly!

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Brettw
It sounds to me like the differential is working correctly. The tires should spin in opposite directions when they are being held from freely rotating by being in gear. If the transmission is actually in neutral and not preventing the rear end from moving, the tires should turn together in the same rotation. As it is, it sounds to me like you are not in a neutral position. Just my thoughts. Without more info it is hard to say. You can try turning the input shaft on the transmission and see if that rotation is transferred to the rear tires to determine if you are in fact in gear.

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fpappal
Thanks for the suggestions. I checked and it is indeed in neutral. The input shaft spins freely in neutral. If I put it in gear it will no longer spin. Will I need to remove the differential from the axle to make any repairs it may need? I put this back together about 4 months ago and my memory is a little foggy. Thanks.

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Brettw
quote:
The input shaft spins freely in neutral. If I put it in gear it will no longer spin.
Cupala things: One: you may have to turn the input shaft a fair amount to get noticeable rotation in the rear wheels, remember, it is spinning when under power at many rpm's and that is geared down to the relatively low rpm's of the rear axle. Two: If the rear of the tractor is still off of the ground, and you put the tractor in gear, you should be able to turn the shaft. It won't be super easy as if freewheeling, but you should be able to turn the shaft and then the rear wheels should definitely turn. With what you have said so far, it sounds like you have a locked up gear or some other issue preventing the axle from turning. That is why it won't move forwards or backwards, but will spin in the opposite direction when lifted off of the ground. The fact that they turn in opposite directions tells you the differential is working, and the axle is not being allowed to turn, I believe.

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