Cub cadet 1250 hydrostatic help needed

[DownNdirt]

Ever since I did a hydraulic lift swap last winter, i have had a problem with the forward reverse lever in my 78 1250. It only goes about three miles an hour, is very unresponsive and only goes up halfway (if that) of what it should. Now immediately after I had to exchange the trunion and springs and pins from the non ported pump which worked fine because i was having so many problems with neutral and not going fast. I would like to fix this, so I need some suggestions ton how to fix this issue. I plan on replacing the damper springs and guide pins. Any help is appreciated.

[J-Mech]

Where did you get the ported pump? Any idea what it was out of?

Are you planning to replace the parts you listed because they are worn out? Or because you are guessing?

Did you look over all the linkage to see if it is binding or something broken?

Did you put new fluid and a new filter on the new pump? What filter? What fluid?

My guess is if you didn't have the issue before you worked on it, you likely didn't put something back together correctly. How about some pics of all the linkage.

[DownNdirt]

The pump was out of a 1450 not sure of year. Had no serial tag. Was planning to replace the listed parts because they don't look too great but they were the better of the two pumps. Haven't really checked it good due to not much tractor time because of work. It got a new genuine cub filter that was listed and hytran utraction (local dealer said it would work just as good as normal hytran.) I'll get some pics after work tomorrow. All the linkages circled in red stayed in the tractor untouched. I took the ones in blue off the original pump and put them on the ported pump.

[J-Mech]

Year is completely irrelevant. Numbers of/on the pump wouldn't tell you anything other than the pump specs.

Go look it over. I'd say it will be obvious. If you don't find the issue, snap some pics and come back for help. No real need to be asking questions if you haven't even looked at it yet. You might find the issue on your own and not need any help.

[R Bedell]

I addition, I would suggest you go to our Technical Library Section and down load the Quietline Service Manual. There is a section dedicated to the Sundstrand Hydro Unit, and how to adjust and setup.

[sawdustdad]

I'm not sure this is the conventional or even recommended diagnostic method, but here's what I'd do.

Pull the tunnel cover. Put the rear axle on stands. block the front wheels. start the tractor and put it in forward. Reach down and try to pivot the cam plate back and forth. Do you get more speed? Is it loose? If you don't get more speed, is it hitting something restricting it's movement? Are the springs on the trunnion weak? Move the trunnion itself back and forth. Does that give more speed?

look at the rest of the linkage. It is loose or is there slop? Something should be apparent.

[DownNdirt]

So an update for my issue. Removed the tunnel cover and went looking for problems. One major one my brother found that might be causing my issue is the brake neutral return link is too short causing it to not go far enough for full speed. When I get time I will remove pin and lengthen rod and see if it helps and update.

[DownNdirt]

So I finally figured out why my tractor went so slow. The neutral return linkage was set up for the non ported pump and when I swapped pumps I never knew the clevis needed screwed out. Did that today and it is perfectly fine now.

[sawdustdad]

Wow, great that you fixed it! I didn't realize there was a difference for the two pumps. Good to know.

[Mudrig150]

Originally Posted by sawdustdad

Wow, great that you fixed it! I didn't realize there was a difference for the two pumps. Good to know.

On an older style tractor, the neutral return is about 1/4" farther back, so if you're swapping a newer pump onto an older tractor or vice versa the neutral return linkage must be adjusted.