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AC712H

Has anybody made a sundstrand smoother

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jlasater

Doubtful. You'd think something as heavy as a wheat combine would have enough mass to make the hydro direction changes smooth but they can be quite jerky. Same for our little tractors, though I can't recall disliking mine. Beats the heck out of a clutch and gearshift :-)

There are springs in the pushrod for the hydro on my 716H, but I found it worked better when I replaced those with a piece of fuel hose to stiffen it up.

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acfarmer

I don't see how they could be any smoother as you can ease them in forward or reverse.Sounds like you have some of the shifting linkage in a bind and have to put alot of pressure to make it move and when you do it then goes farther than necessary.I'd give it a good going over with PB Blaster.

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HubbardRA

I thought mine was terribly rough and didn't have many good words for the way it shifted, till I found that the 6 bolts that hold the side plates to the BGB were loose. After tightening these bolts the shifting is much smoother. The whole transaxle had been rotating when I put it in gear and really jerking the tractor. Doesn't do that now.

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AC712H

I will definitely check all these out. I am guessing lack of maintenance and abuse over the years has worn some of these parts.

Thank you all for your info. I was not sure where to start.

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MikeES

Make sure your spring box is working properly. The spring box is located on the control lever shaft half way back to the hydro. The springs act like a cushion and give a slight delay in the lever movements. This spring box can get rusted/gunked up and the springs no longer function. Also a PO may have done something to lock up the spring box i.e. like washers to make the hydro more reactive.

The hydro is not near as "jerky" if the spring box is working.

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rfsmith1952

They do surge when the side bolts are loose. I also cleaned the rail on which the lever rides, and slightly bent the neutral stop down a little more so I felt a positive thunk when I hit neutral. Be careful there, because you can bend the rail or stop too much and it will fight you to go into reverse. I'll tell you, I was afraid of that hydro for awhile, because of the surging and lurching and lack of speed control. But now with it working the way it should, and learning not to OVERCONTROL it, I can back a trailer up on a dime. Don't overlook the pedal either. In certain circumstances using the pedal before the lever is the right thing to do. MIne is a Vickers though.

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Kent

One of the reasons that people will modify the spring box is because under heavy loads pushing forward, such as trying to stop a heavy trailer or on steep downslopes, the spring will compress and the tractor will essentially freewheel. I had that problem when mowing down a steep hill behind my barn - runaway tractor! I removed the spring and replaced it with a section of rubber hose. It takes more caution to engage it now, because it is so sensitive, but I've had no runaways since...

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Burntime

Yep, I stacked extra washers on mine as the spring was week on my old trusty 17gthl. It was much more crisp. I have also seen people cut copper tubing and put it in with no give, it really was touchy...

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MikeES

Kent, my place is on a fairly steep hillside and I have hauled very large loads of wood on a trailer (weighing at least twice as much as the tractor) down the hill and have not had this experience of free wheeling...it may be compressing the spring but I am traveling quite slow to begin with so the slight increase in speed from the compressed spring may not be noticeable.

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Kent

Mike, I think it's a combination of two factors:

1. How much the original spring has weakened/softened over time, and...

2. How much load the tranny is trying to hold back.

That only happened to me once, but once was enough to make me want to "fix it" so it wouldn't happen again, after I stopped shaking... I jumped a shallow ditch and "plowed into" my garden, dragging my vacuum cart behind me. After this mod, it would actually scoot the back tires when going down the hill with a full load in the canvas top vac cart.

One of my complaints with the Simplicity clutch/brake design is that the natural tendency in that type situation is to hit the brake -- which means you've temporarily clutched the tractor before you can apply the brakes, gaining even more speed...

I had a runaway on a Ford 8N years ago with a trailer load of square hay bales behind it. I shut the engine off, without clutching, stood up on the brakes, and slowed it enough to finally regain control before jack-knifing or something... In that case, I had runout area to regain control.

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