Stumpy 1 #1 Posted June 17, 2020 (edited) I have a two part issue I was hoping someone could shed some light on. PART 1: I have a 76' C120 with a sunstrand hyrdo trans I was using to haul some firewood last winter. While backing up the trailer I noticed reverse got slower and slower until it barely worked at all. At that point I knew something was wrong so I drove it to my shop and the same thing happened going forward, kept getting slower and slower until it wouldn't move at all (froward or reverse). I figured something in the pump was shot was I took it apart and inspected the slipper faces, they seem ok. Oil level was fine and no metal particles were found. PART 2: I was going to take it to a shop to have it looked at, at that point I noticed that with the tow valve open I was unable to move it. How would that be possible? Edited June 17, 2020 by Stumpy Share this post Link to post Share on other sites
squonk 41,324 #2 Posted June 17, 2020 I had an issue with mine years ago. The hydro motor was starting to bind up. My pump was fine. The motor is meshed with the differential.If your motor is mechanically binding, it will be hard to move. Share this post Link to post Share on other sites
The Tuul Crib 7,337 #3 Posted June 17, 2020 (edited) Sounds like it might be a bad Excelerator spring. If it is wheel horse parts and more does have them I believe. Edited June 17, 2020 by The Tuul Crib Share this post Link to post Share on other sites
squonk 41,324 #4 Posted June 17, 2020 I don't think a spring would keep it from rolling with the tow valve open. Share this post Link to post Share on other sites
Stumpy 1 #5 Posted June 18, 2020 16 hours ago, squonk said: I had an issue with mine years ago. The hydro motor was starting to bind up. My pump was fine. The motor is meshed with the differential.If your motor is mechanically binding, it will be hard to move. You were correct. I did not have the valve plate seated over the dowel pin correctly causing the motor to bind. So issue 2 has been solved. Any ideas what would cause drive and reverse to go out? Share this post Link to post Share on other sites
Kribbie 1 #6 Posted June 27, 2020 I have a c120 auto. I know this isn't the same problem as yours but I have to ask anyway, as I was mowing last nite I came up against a porch post, backed off the post and continued on to other end of yard( slighly down hill) when I tried to turn around it wouldn't go forward, went backwards just fine but I could not make it go in the forward motion at all. so I backed it all the way back to the garage. I am far from a wheel horse tec, so I am asking whay in the world would it do that. and how can I fix it?. thank you in advance 1 Share this post Link to post Share on other sites
pfrederi 17,866 #7 Posted June 27, 2020 First check the plastic slider (yellow) on the motion control. make sure it is moving up and down and making the arm on the pump move also. 1 Share this post Link to post Share on other sites
Stumpy 1 #8 Posted June 27, 2020 I actually just bought a used c121 pump and motor, confident that would fix it. However, I still have the same problem. Oil level good, woodruff keys are good, and the yellow slider looks good to me. It's very possible I bought a bad pump but the fella " assured" me it was good Share this post Link to post Share on other sites
Stumpy 1 #9 Posted June 27, 2020 1 hour ago, Kribbie said: I have a c120 auto. I know this isn't the same problem as yours but I have to ask anyway, as I was mowing last nite I came up against a porch post, backed off the post and continued on to other end of yard( slighly down hill) when I tried to turn around it wouldn't go forward, went backwards just fine but I could not make it go in the forward motion at all. so I backed it all the way back to the garage. I am far from a wheel horse tec, so I am asking whay in the world would it do that. and how can I fix it?. thank you in advance If you have reverse, I could be the acceleration valve, but that's just a guess 1 Share this post Link to post Share on other sites
Kribbie 1 #10 Posted June 28, 2020 (edited) I just tore into this. ( taking sheet metal off) the slider looks to be working fine, moves up and down as should seems to be attached to everything it is to be attached to. Edited June 28, 2020 by Kribbie Share this post Link to post Share on other sites
Kribbie 1 #11 Posted June 28, 2020 Stumpy that sounds like a good guess. but I have no idea what that is. everything looks to be hooked as should. I was mowing yesterday and put it up against a porch post trying to get just a tad closer. well after that is when it guit going in the forward direction Share this post Link to post Share on other sites
Stumpy 1 #12 Posted June 29, 2020 Kribbie, I'm not gonna lie, I have never actually done it myself but I have attached the manual for the c120 sunstrand trans. Page 40 should help ya with that sundstrand_90.pdf Share this post Link to post Share on other sites
Stumpy 1 #13 Posted July 9, 2020 Any luck Kribbie?" Share this post Link to post Share on other sites
