GT-14 Loses power forward, not backwards

[FatJackDurham 318]

Although you wouldn't know it by the dent in my car, my GT-14 has a serious power loss problem in forward gear. When I put the lever forward, I hear a hydraulic whine as the tractor starts to move. On the flat, the tractor drops into full speed and seems to run fine. With any upslope, though the transmission whines and tractor starts to lose power, sometimes coming to a stop. If I only engage the lever just a little, I can sometimes inch up the hill. 

 

However, in reverse, there isn't the same issue. I have read the Sunstrand manual troubleshooting and it seems to suggest the problem is in the control linkage, charge valves or acceleration valves.

 

I was curious if anyone else has had this issue or if you have suggestions based on the description.

 

Also, the Sunstrand manual says to change the fluid first before other diagnostics, and it says to use transmission fluid instead of engine oil before 1972, but it also suggest that some have been converted to engine oil after a full drainage and cleaning. Is there any way to tell what type of fluid is in my transmission? I assume transmission fluid is much thicker than oil, but I want be sure before I try to change the fluid.

Never mind, I should have looked at the hydro gear section, as that is what I probably have. I assume there is no way to tell externally if it's been converted to the piston-piston transmission?

 

Anyway, the hydrogear section indicates the need for a tune up, Wheel-a-matic manual page 3. 

 

Is this a different manual than the Sunstand? 

[pfrederi 17,147]

Red Fluid is ATF (Dexron).  Tan is Motor oil.

 

If the hydro motor part looks like this then it is still a hydro gear /Wheel- a-matic  (same thing and both Sundstrand..  The unit is lying on its side in the picture the figure 8 shape will be vertical.

By all means do the tune up

Edited May 22, 2017 by pfrederi

[953 nut 51,736]

3 hours ago, FatJackDurham said:

acceleration valves.

The Acceleration valve springs are likely to be the culprit. They modulate the flow of fluid to produce a smooth acceleration and when the springs go bad the valve won't open properly. The acceleration valve at the rear of the unit is for forward, the one at the front is the reverse valve. Each has two springs on it and you may as well change all four. Member @refracman hooked me up with a person who had a bunch of these made up a few years back. The hardest part of the job was removing the left tire, fender and other stuff; then putting it all back.

Take a look at the Sundstrand Manual and you will see the steps involved.

[FatJackDurham 318]

On 5/22/2017 at 5:48 PM, 953 nut said:

The Acceleration valve springs are likely to be the culprit. They modulate the flow of fluid to produce a smooth acceleration and when the springs go bad the valve won't open properly. The acceleration valve at the rear of the unit is for forward, the one at the front is the reverse valve. Each has two springs on it and you may as well change all four. Member @refracman hooked me up with a person who had a bunch of these made up a few years back. The hardest part of the job was removing the left tire, fender and other stuff; then putting it all back.

Take a look at the Sundstrand Manual and you will see the steps involved.

 

Yes, I have been reading the procedure. If I understand you, there is no available rebuild parts kit? you have to source the springs from third party or enthusiasts?

[pfrederi 17,147]

You might try calling LJ Fluid Power.  They have some stuff for the Sundstrands.

 

(269) 623-4150 · 10118 S M 43 Hwy Delton, MI 49046

[953 nut 51,736]

3 hours ago, FatJackDurham said:

 

Yes, I have been reading the procedure. If I understand you, there is no available rebuild parts kit? you have to source the springs from third party or enthusiasts?

As far as I know that is the situation, just passing along what we know. Remember, we are keeping forty to fifty year old machines going and in spite of our enthusiasm for our  we are members of a rather limited market. I was unaware of  L.J. Fluid Power, glad Paul chimed in.