1968 cub cadet hydrostatic drive

Fri Jun 25, 2010 7:52 pm

hey yall, i am a newbie at this. my dad asked me to find out some info for him.here it is. he owns a 1968 cub cadet yard mower equiped with a kohler motor.it belonged to his father very sentimental. it will no longer go forward or backward.......just started this....... we pulled the plug out of the rear end and were able to feel fluid with our finger, to my knowledge the fluid has never been changed.....is there a different reservoir for the transmission other than the rear end....... i do not know what hydro drive is .......any help would be appreciated. Thank you in advance, David

Re: 1968 cub cadet hydrostatic drive

Fri Jun 25, 2010 8:33 pm

Check the roll pin in the drive shaft. These can wear out and fall out.

Re: 1968 cub cadet hydrostatic drive

Tue Jun 29, 2010 7:17 pm

hey cubmaster thanks for your reply. i am not positive but i don't think it has a driveshaft. ai am lookin for a schematic now. thanks for your help

Re: 1968 cub cadet hydrostatic drive

Tue Jun 29, 2010 8:00 pm

There is no other reservoir, you just take the back cover of the tranny off to drain the hydraulic fluid (actually Cub Cadet Hytran), then install a new gasket, and re-fill until it runs out the plug that you pulled off to feel the fluid. There is also a spin-on oil filter on the front of the tranny that you should change, again, a Cub Cadet part.

If this is something that just started, it is likely the roll pin in the drive shaft that has broken. Yes, your tractor is shaft driven, with a steel drive shaft that runs between the engine flywheel and the input gear on the transmission. Below is the same transmission, out of a Cub Cadet 125. If yours is a 1968, it is either a 105 or 125 (10hp or 12hp) but they used the exact same tranny.


This gives you a good shot of the oil filter, and the rubber, flexible coupling above it is where the drive shaft attaches. There, the drive shaft has a T which bolts to the rubber coupling. On the other end of the drive shaft there is a solid roll pin that fits in a notch on the flywheel. That is likely what is broken off and allowing the drive shaft to remain still while the engine is turning.

Now that I've looked at the picture, there is another option. On the very top of the hydro pump (silver thing) there are two big hex nuts with buttons in the middle. Those are the hydraulic dump valves. If they have corroded and stuck down, the transmission will act like it is not working. In reality, those buttons open valves that just let the hydraulic fluid through without doing any mechanical work (moving the tractor). During normal operation they should pop up. A quck test for this is to see if you can push/roll the tractor while the engine is off. If so, the dump valves are stuck down, and allowing the fluid to move freely. If you cannot push the tractor around, then this is not the problem.

Good luck,