125 flywheel or drive cup help needed

[jmroy]

The tunnel cover on the narrow frames can't be removed, you have to remove the drive shaft from underneath. If the drive shaft has been in there for 40 years its going to be a major PITA to get it out. The easiest thing to do is to stand the tractor up on end and work on it that way. Just make sure you tie up the front end so it wont fall over, I use a chain fall but even a good piece of rope will work.

[darkminion_17]

That is the way I do it also.A lot easier and dirt don't fall on your face.Are the threads on the crankshaft damaged?A machine shop is a good choice to get that done if you don't have the right tools.I have a drive cup in good shape,let me know

[mrcubcadet]

I recently put new parts in the drivetrain, and had the shaft redone on my 105.


I also put the tractor on it side, once I got the motor out.

[Matt G.]

Another way is to support the tractor with jackstands under the footrests, disconnect the brake and hydro linkage, and pull the rearend out of the tractor with the driveshaft attached. Then you can fix the driveshaft, the trunion slot, and the cork gasket, and adjust the brakes very easily. If you turn it on its side or on end without draining the rear you'll lose a bunch of Hytran out of the breather.

Also, don't use a nylock nut- the insert will probably melt from the heat. It's not necessary anyway, a properly torqued OEM nut will not back off.

[Flatbedford]

The damaged nut is an expanding lock nut. I bought the nylock figuring that heat would not such an issue in this location. Which brings me to my next question. How do I keep the engine from turning when I torque this nut?

[Flatbedford]

Here's some pictures.
Drive cup.

Drive plate


Drive shaft


The nut that had come loose. First is the damaged threads.


The threads on the shaft. Only the first one or two are kinda rounded over from the loose nut rolling around in there. I think they could easily be cleaned up if I had the right size die.


I am assuming all these parts should be replaced. It is tempting to simply fix up those threads and put everything back together with a 1/4" bolt instead of the dowel.
If nothing else, at least I was able to clean 43 years of grass, dirt, and oil out of a few nooks and crannies.

[Matt G.]

I would not just put that all back together. A 1/4" bolt is not acceptable there. The crank will be fine, but you need a new (correct) nut, the driveshaft is shot, the slotted coupler needs welding and re-machining at a minimum, and the drive cup would also need to have some material added with a TIG welder and then be re-machined.

[Flatbedford]

I borrowed the die and tap and fixed the threads on the shaft and the nut. Yes, I do need new parts. I'll have to do some shopping.

[duce225]

I know what your going through. I am into the same project+ from a guy that thought more weld is better. And with the driveshaft being out of balance from the poor welding job, it has done damage to the crankshaft and bearings.

[Flatbedford]

What a mess!!! How can you even get all that apart?