I just posted this elsewhere... but i'll repost it. It concerns how to remedy hydro creep. I just did this 5 days ago
You'll have to interpret some of this as i didn't go into full detail... it's easy to understand though once u get under there and look at your problem and see what does what. I refer to a 107 and 147 in this... but the process is the same for all hydros... cuss, pull hair, break knuckles... fix problem, repeat to get just right. Enjoy.
Your linkage is all screwed up. That's the problem you have. There are 2 linkages on a Cub Cadet... one that leads from the brake to the transmission... so when u step on the pedal the tranny kicks into neutral, and one from the SR lever to the hydro.... These are part of your problem. First you must ensure that you do not have any hydro creep going on. Here's how to fix this:
1: Jack up the left rear wheel of the tractor. The on the transmission, Loosen the 2 bolts that hold the Triangular slotted plate to the pump on the hydro. Loosen just enough to let the whole deal slide to the bottom of its adjustment. Lightly snug the bolts enough so that you can move it by tapping.
2) Start the tractor and run at about half throttle... crawl underneath it... and be very very careful under there.... No long sleaved shirts for this. Once underneath take a punch and hammer and tap the mount for that linkage upward until the tire stops moving. Then tighten the bolts (or as I do... just bottom for now until u know you've gotten it... the top one is a real bitch to get to on a 147... I have a 107, same basic machine).
3) Now that the wheel has stopped moving, shut off tractor, and set the parking brake. The linkage that goes from the brake pedal back to the triangular plate on the hydro needs to be set so that when u step on the brakes the hydro goes into neutral. What I do here is set the brake... move the linkage (turn either way) to where I think will be neutral and then start the tractor and see if I found it. Yes... it's a bit unscientific, and it's a chase, but it works... and it's easier to say that than get in depth on which direction to turn it... you'll figure it out. You simply want the brake pedal to pull the hydro plates to the neutral position. I.E... forward into that slot on the Tri plate, and in turn stopping the wheels from any movement. Although.. if the linkage is old and worn... you may get close... but not spot on. That'll have to do.
4) Now that you have the hydro creep fixed and the neutral position found while the brake pedal you must adjust the SR lever to acknowledge true neutral. To do this you must find the threaded linkage with the two ball joints that goes from the bottom of the SR lever to the bottom of the triangular plate on the hydro. Set the parking brake so the tranny is in neutral. Next, pray to whatever God you wish... or better yet, every one that you can think of that the linkage isn't frozen due to rusting(it costs nearly 70 bucks). Go inside... get a shot of Jack... pray some more... and loosen the jamb nut and twist it.
If you're lucky and it is free the linkage will either lengthen or shorten depending on the direction turned. If you're unlucky you'll have to remove it(words can't describe how much of a pain this will be) and attempt to free it up without twisting it off. Remember... it has a right hand thread on one end, and left hand on the other... so be careful when freeing it. Reinstall when done.
The trick here is since the hydro creep has been fixed and the brake pedal linkage adjusted so that it pulls the hydro into neutral to stop you want the SR lever to also go to neutral when the brake pedal is stepped on. That is what turning the threaded rod between the SR lever and the triangular plate does. It adjusts the SR lever to show true neutral and speed selection.
Once this has been done, and all bolts tightened back up fire it up and give it a try. You should be able to step on the brake and come to a dead stop or close to... depending on how bad your linkages were worn in the first place. You should also be able to pull the SR lever into neutral and easily come to a dead stop. If not... start with #1 and try it all again. Don't get discouraged... it's a pain in the but to do... especially on a NF. I have a 107... and it's just a 147 with a smaller engine... space is tight under there. You'll soon figure out exactly how everything works under there and it will become easier to understand what Iâ€™m saying, and how to adjust the linkage. Hope this helps everyone who has a hydro creep, or linkage related problem. Cheers.