Cub Cadet Hydrostat losing power

ptplumer · May 2, 2009

I am probably asking questions about a smaller machine than anyone here wants to acknowledge, but it is worth a shot. I have a 60's vintage model 129, which has been a workhorse for me. It has started losing power on the slight incline in my yard when mowing. The motor was fresh about 2 years ago, and the motor does not seem to bog down, but it slows noticeably and does not pick up even when I get to a level grade. It also seems to do the same thing in a sharp turn. THe hydro fluid level is up and the fluid is clean. My local dealer gave me a story that I think is bogus about whether I am using a genuine Cub Cadet filter (which I am) and how the by-pass valves (to open the hydrostat for towing) may be problematic. Anyone have any good advice, or am I just trying to revive a dead soldier?

KennyV · May 2, 2009

ptplumer said:
am I just trying to revive a dead soldier?

That old Cub Cadet is always going to be worth repairing.
I have a 1450 that is about the same age as your CC. Great machine and it has thousands of hours.
If your hydraulic pump/motor starts wearing and leaking internal use a higher viscosity oil. If the bypass valves are not closed you will have a problem, to insure that there is not something in them open while engine is running to flush the valve out. Then securely close. If the filter is plugged up you will have this problem or if you are using an oil that is to light.

I had this problem with some hydro oil I bought from the IH dealer years ago... he gave me the wrong stuff. I have been running a HI-tran equivalent from Tractor Supply for the past 20+ years.
Keep that Cub going... KennyV

ToadHill · May 2, 2009

I have a 127 and have mowed hills with it for years and it has always slowed down as I clime the hill. All I've ever done is to push the hydro lever to a little faster speed and back off when I get to the top of the hill. I've had a number of older hydro Cubs and all have done the same thing, I think it's just a normal situation for these units.

ptplumer · May 2, 2009

I will try the higher Vis oil, pretty sure what I have in it is Hytran product. I have always been one for preventive medicine before so when this became more noticeable, I wanted to jump on it. I dont have but about $500 in the bundle including the tractor, mower, snowblower, and dozer blade, so I want to give it the attention it deserves. The dealer was wanting to hit me fore $1000. Thanks for the input.

ptplumer · May 2, 2009

Any suggestions on tightening up the pivot point on the front axle? If I am going to work on this, this is another thing I was going to address. Thought about drilling out the axle and putting in aq bushing.

2manyrocks · May 2, 2009

The most likely cause is the trunion shaft assembly on the outside of the transmission. The slots get worn in it over time and the spring gets weak. When you go up a hill, the control loses position and you slow down.

Here is a link to the repair. http://ihregistry.com/ref/trunion1.html

Also, take a few moments and look at the other common repair issues while you're there. It will probably answer a lot of your questions as the IH Cubs tend to have the same issues.