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Anybody Rebuild Sunstrand Hydros?

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#1 Luke OFFLINE  



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Posted July 10, 2014 - 11:58 PM

Looking for someone to go totally through my MF 1655 sunstrand hydro. It works fine except for what I believe are the centering pins are broke off.....won't return back to the neutral position on hydro pedal.....kinda dangerous to operate this way!
While I have the hydro out of tractor I want to go through it completely and rebuild it and reset pressures to original specs. Id do it myself but have no time.
Does anyone know of a really good company that rebuilds these units or will exchange mine for a good one? Thanks
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#2 JDBrian OFFLINE  


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Posted July 11, 2014 - 04:15 AM

You might check with our sight sponsors. If they can't help you I would look for a local Sundstrand dealer. It will be pricey to get it rebuilt and they normally last a long time(thousands of hours) if maintained. You may be better off finding a good used one to sub in if that one ever gives you grief. 




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Posted August 31, 2014 - 04:12 PM

The Sundstrand in your tractor has a 1000 hour life expectancy at 200 hours per year and a continuous 2500 psi operating pressure with peaking pressures of up to 4500 psi.


Your chance of achieving those pressures without some really serious ballast and operating in low range are somewhere between slim and none without breaking traction first. You will never operate at 2500 psi continuously with a normal GT's tasks. Well, maybe Ducky when he's pulling his triple 12" bottom plows.


For the pressures that are normally seen for a GT, figure a life expectancy of more like 5,000 - 10,000 hours. Lawn mowing and snow blowing require very little pressure in the hydro. The pressure might peak at 1500 psi on a hill.


Neutral centering is done with springs on the brake linkage. There is nothing in the hydro for finding neutral.


The max pressures are set at the factory with springs in the various valves. Other than replacing broken parts or cleaning, there is nothing user serviceable for adjusting pressures. Pressure depends on the resistance to flow when doing work and the valves only limit the maximum pressure allowed. For your Sundstrand inline type hydro, that's the 4500 psi setting of the acceleration valves. You really, really, don't want to mess with that one.


These hydros are as close to bullet proof as you can get. The weak points are the charge pump drive pin (sometimes they break) and the spring pins holding the swash plate to the trunnion (they sometimes work their way out). Both are simple and inexpensive repairs.

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