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Discussion Starter #1
I recently bought a 9670sts. The problem is when i removed the sievebox I found alot of damage and problems in there, looks like at some point the whole box got loose and was damaged.

Now I want to know if there is any way I can slow down the speed of the sievebox by putting in a larger pully or some other way.

Is there anybody that perhaps have made a modification that can help my with this problem.

Greetings.
 

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How many separator hours on your machine? They do fail on any model over time. Some Deere combine fail sooner than others. Pulling the top chaffer out to get a clear inspection each year is critical if you ask me.
 

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Discussion Starter #3
It has abouy 3000 seperator hours on. I knew the normal sts, not the "Bullet rotor", broke the sievebox alot, heard about a guy that replaced the normal pulley that pulls the sievebox with a larger pully and since the no more breaking.

Hope somebody has a plan on here.
 

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Ooohhh Deere
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Any reduction in speed will greatly reduce its ability to work. Your sample will be a mess and you will create a sieve grain loss issue

do not modify the speed. It’s designed to work best at a certain speed for that machine

if all bushes, bearings, arms and components are in good order and installed correctly you will get years of trouble free service from the JD sieve box frames
 

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at 1900 sep hours on our 9870 the sieves grenated twice already, poor design on deere's part.
as for slowing the sieves down it can be done, it would actually operate almost the same speed a 9600 combine would run the sieves. As for performance it will be a lot slower combine if you do this.
if you made it to 3000 seperating hours your lucky. put new arms and bolts in, straighten the frame and off you go.might as well drop an adjustable pre chaffer into the combine while your add it
 

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Any reduction in speed will greatly reduce its ability to work. Your sample will be a mess and you will create a sieve grain loss issue

do not modify the speed. It’s designed to work best at a certain speed for that machine

if all bushes, bearings, arms and components are in good order and installed correctly you will get years of trouble free service from the JD sieve box frames
I am not convinced that slowing down sieves reduces capacity. I run a New Holland combine that has two different sized drive pulleys to give you the ability to slow the sieves down for small seeds like grass seed. I choose to run mine in slow speed for every crop I grow and have no issues with sieve loss. In fact If anything I feel sieve loss is less than when I have tried running it in high speed. Let the fan do the work. New Holland sieve frames have been known to break so I prefer to keep stress to a minimum.
 

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Ya it is the weakest spot on the 500,60,70 series deere combines. We have replaced or fixed four or five of them over the years.
 
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