129 hydro issue

[J-Mech]

Guys, there is NO system relief valve on these hydro's. There are check/charge valves.... you know, the ones that always leak. But they are NOT relief valves. There is a relief valve on the charge pump. If it was set ridiculously high, it could make it more responsive.... but it would have to be stupid high. Like 1000 psi or more. The charge pump can't handle much more than 1000 PSI. If it is a ported pump, there is an implement relief valve also. It is separate from the other one. But NO system relief valve.

So, if you move the lever over 1" it gets stupid huh..... have you taken the tunnel cover off and watched the linkage move while you move the lever yet? Got a video for us yet?

[cooperino]

Originally Posted by J-Mech

Guys, there is NO system relief valve on these hydro's. There are check/charge valves.... you know, the ones that always leak. But they are NOT relief valves. There is a relief valve on the charge pump. If it was set ridiculously high, it could make it more responsive.... but it would have to be stupid high. Like 1000 psi or more. The charge pump can't handle much more than 1000 PSI. If it is a ported pump, there is an implement relief valve also. It is separate from the other one. But NO system relief valve.

So, if you move the lever over 1" it gets stupid huh..... have you taken the tunnel cover off and watched the linkage move while you move the lever yet? Got a video for us yet?

Tunnel cover is off. I have moved lever with engine off. I can do it with it running but that won't change how the linkage moves. The two plates move independently and neither show any sign of heavy wear or being excessively tight or loose. Jon, I will put it this way. What i did to try to control it is this.. I left the unit at idle, then i moved the lever to forward slowly as far as it would go. I had better control of speed by using throttle to make go faster than the hydro lever. By time I got to full throttle I was well over the top speed of any GT I have ever owned. Top speed to the point that I could only do this on flat pavement to maintain control of the tractor.. Way faster than I feel this tractor should really go. Is it possible that the charge pump relief is broken internally and wide open?

[DeltaCub]

Originally Posted by cooperino

Tunnel cover is off. I have moved lever with engine off. I can do it with it running but that won't change how the linkage moves. The two plates move independently and neither show any sign of heavy wear or being excessively tight or loose. Jon, I will put it this way. What i did to try to control it is this.. I left the unit at idle, then i moved the lever to forward slowly as far as it would go. I had better control of speed by using throttle to make go faster than the hydro lever. By time I got to full throttle I was well over the top speed of any GT I have ever owned. Top speed to the point that I could only do this on flat pavement to maintain control of the tractor.. Way faster than I feel this tractor should really go. Is it possible that the charge pump relief is broken internally and wide open?

You may be over thinking this issue! Is the hydrostat lever on the dash very easy to move? It usually is loose on these old tractors. There are two style of control linkage. One is easy to adjust...the other needs new parts. If the linkage is loose it can can cause the the speed to be eratic. If you find that as the tractor is moving and it speeds up by itself when you let go of the handle...it is not possessed but the linkage is loose and needs attention.

[J-Mech]

Originally Posted by cooperino

Tunnel cover is off. I have moved lever with engine off. I can do it with it running but that won't change how the linkage moves. The two plates move independently and neither show any sign of heavy wear or being excessively tight or loose. Jon, I will put it this way. What i did to try to control it is this.. I left the unit at idle, then i moved the lever to forward slowly as far as it would go. I had better control of speed by using throttle to make go faster than the hydro lever. By time I got to full throttle I was well over the top speed of any GT I have ever owned. Top speed to the point that I could only do this on flat pavement to maintain control of the tractor.. Way faster than I feel this tractor should really go. Is it possible that the charge pump relief is broken internally and wide open?

No, that is not possible.
The 129 should run about 10mph. Shouldn't be any faster than your 1211.
Only way it can be faster than it was from the factor is if someone took the hydro apart and ground the back side of the swashplate off. It bottoms out against the case at full speed... in forward and reverse. Only other way it can be sped up if larger rear tires. All the ring and pinion sets are the same speed.

I still think you just haven't got used to the left hand hydro......
But I'll give in if you find something wrong. I like giving you a hard time.

[cooperino]

Originally Posted by DeltaCub

You may be over thinking this issue! Is the hydrostat lever on the dash very easy to move? It usually is loose on these old tractors. There are two style of control linkage. One is easy to adjust...the other needs new parts. If the linkage is loose it can can cause the the speed to be eratic. If you find that as the tractor is moving and it speeds up by itself when you let go of the handle...it is not possessed but the linkage is loose and needs attention.

Thanks for the input.. Its really not erratic at all. It does the same thing every time. I watched the lever for looseness and the rod that runs down to move linkage. All moves freely but not loose. I would not call what I am getting erratic. Its more a feeling of going from little speed or normal speed to wide open but then if i push farther it goes even faster. The top end on this thing the way it is right now is so fast you cant control the steering which is not great but is better than the one I mow with. The engine is not over revving so my thinking was hydro. SO the question is if i turn the hydro at 3000 rpm what in the hydro controls the top end as far as speed goes? I would have thought relief valve but J-mech says there is only one on charge pump. If that one is wide open will it make the tractor over speed? I can control the speed but really have to concentrate on that lever to do so. Im serious.. anyone out there with a k301 hydro wanna race?? Im bone stock and I bet I smoke ya.. LOL.. im joking but its sorta the truth.

[J-Mech]

We posted at the same time..... I answered your post #15 questions in post #14 because I'm that good.

[cooperino]

Originally Posted by J-Mech

We posted at the same time..... I answered your post #15 questions in post #14 because I'm that good.

At 10 mph I would have control of this tractor. Its higher than that. I know its possible because I'm living it. No one has had this hydro apart unless they really good at hiding wrench marks on bolt heads.

[DeltaCub]

Put some slicks on it...a cheap set of flame decals and go hang around the local race track. Who knows you may race an old rustang and win!

[J-Mech]

Originally Posted by cooperino

At 10 mph I would have control of this tractor. Its higher than that. I know its possible because I'm living it. No one has had this hydro apart unless they really good at hiding wrench marks on bolt heads.

I bet it isn't over 10 mph. It was only rated at 8. You sure that engine is running 3600?

Maybe you better back it off if it's too much for you. Detune that pig. Don't want you to rip your dress getting on and off of it.

[DeltaCub]

Originally Posted by DeltaCub

Put some slicks on it...a cheap set of flame decals and go hang around the local race track. Who knows you may race an old rustang and win!

Or you can race this guy! Yee Haw