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Stumpy

76' C120 Sunstrand hydro Transmission issue

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Stumpy

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 by Stumpy

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squonk

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.

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The Tuul Crib

Sounds like it might be a bad Excelerator spring. If it is wheel horse parts and more does have them I believe.

Edited by The Tuul Crib

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squonk

I don't think a spring would keep it from rolling with the tow valve open.

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Stumpy
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?Screenshot_20200617-214740_Drive.jpg.32daf9caf71f3995e2da3fba810d7e89.jpg 

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Kribbie

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

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pfrederi

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.

 

 

Inkedslider_LI.jpg

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Stumpy

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

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Stumpy
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

Screenshot_20200627-154559_Drive.jpg

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Kribbie

1689502002_DSCF91032.JPG.181ea8eab3aaf51eca965029f1b351e7.JPG213780505_DSCF91071.JPG.0f131cd1bf389e37dbe22ed4375a51e7.JPGI 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. 1179645674_DSCF91042.JPG.05ae4f98e3d2d3bc226b94efba0893d9.JPG283473274_DSCF91021.JPG.1e70bfe028d9dbf64fc92a22a21784a7.JPG101136232_DSCF91001.JPG.8cccfc7873bed5b27be0a376aa0deae0.JPG

Edited by Kribbie

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Kribbie

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

DSCF9101[1].JPG

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Stumpy

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

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Stumpy

Any luck Kribbie?"

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