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Discussion Starter #1
Looking at a few machines with the smaller 2.75'' (70mm) lift cylinders, will they lift a 35' or 40' fd70? Think I already know the answer but I thought Id make sure.

Can they be swapped easily to the 3.15" (80mm) cylinders, as in just unbolt or does something else need to be changed?
 

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they might lift the header but the if you do change you have to change from a single acting cylender to a double acting i do beleave i did it once a year ago you also have to change a valve if i remember right . there is also a difference in the feederhouse frame
 

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so we cant just find a set of big cylinders and stick em on our 9660? gettin a 35ft FD70 but i have tried to lift a 36ft 974 and it wouldnt hardly do it, and our dealer already cranked the pressure on ours.....
 

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There seems to be a lot of confusion on the new style 80mm cylinders with "2" hoses. The system is NOT double acting, it works the same as it always has, pressure up gravity down. The front hose actually is tee'd into the reel drive return oil to sump and just has static oil on that side which flows freely back and forth with no pressure on it at any point. Now to the point at hand, The 36' drapers were out before the new 80mm style lift system. The 70mm cylinders at that time worked fine for 12rows and 36' deere drapers. There is no other lift pump option so all you can do is upgrade the cylinders and make sure you are putting out at least 3300psi. Some combines came out of the factory only putting out 2400 and would barely lift an 8 row.
 

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Discussion Starter #5
jdtech, what do those pumps max out at? How many years have the 80mm cylinders been a option?
 

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The 80mm cylinders came out with the 70's combines and the pumps are rated at 3190psi but max around 3400psi I believe. There is no purpose for the front hose on the cylinder. These cylinders are used orginally on "DEERE" industrial equipment like loaders and as double acting. On the combine they are only single acting and so the front hose is routed to static oil so it does not draw vaccum.
 

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Also I found the retro kit for the 80mm cylinders its AH231414 for the small parts to add return lines for the front hoses to the reeldrive system. You just need the cylinders and that kit to upgrade a 60's or 70's to the 80mm system.
 
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