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Discussion Starter #1
So last harvest the sieve box on our 770 broke apart on the left side right above the cut out for the clean grain auger. The machine has close to 2000 separator hours.
replacement costs $ 8000. We ordered one and at the time was only one!!! in stock in NA.
we parked the combine and installed it last week. We were told worn mega bushings in the shaker arm could be the cause. We replaced all bushings. the left side ones were bad but the right ones were still not bad. I understand that the whole cleaning is equally driven from both sides. But why has the left more wear?

So having almost done the repairs on the 770 we moved over to the 760 tt to replace the upper sieves with TM 6 sieves. Just to make sure this one has no problems we pulled the lower left sieve out and low and behold this box has a crack in the same spot going up to the angle where the sieve sits on. My son reached from underneath to feel the outside and the reinforced plate is cracked as well.
Both Combines are 2011s and the parts book shows this part # was only used in this model. I don`t know if Claas improved this ****ty poor design in the newer ones or not, the parts book shows the same image, just different numbers. All I found was the 480 had a different box and it looks a lot stronger. Maybe they weakened the sieve box when they put in the jet stream fan and the larger clean grain auger.

pics will follow
 

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Interesting and thanks for posting we’ll check ours too. I can tell you though like you said the 480 never had a problem there or the 590’s and we ran them till the bushing was completely gone a time or two!
 

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Discussion Starter #3
So last harvest the sieve box on our 770 broke apart on the left side right above the cut out for the clean grain auger. The machine has close to 2000 separator hours.
replacement costs $ 8000. We ordered one and at the time was only one!!! in stock in NA.
we parked the combine and installed it last week. We were told worn mega bushings in the shaker arm could be the cause. We replaced all bushings. the left side ones were bad but the right ones were still not bad. I understand that the whole cleaning is equally driven from both sides. But why has the left more wear?

So having almost done the repairs on the 770 we moved over to the 760 tt to replace the upper sieves with TM 6 sieves. Just to make sure this one has no problems we pulled the lower left sieve out and low and behold this box has a crack in the same spot going up to the angle where the sieve sits on. My son reached from underneath to feel the outside and the reinforced plate is cracked as well.
Both Combines are 2011s and the parts book shows this part # was only used in this model. I don`t know if Claas improved this ****ty poor design in the newer ones or not, the parts book shows the same image, just different numbers. All I found was the 480 had a different box and it looks a lot stronger. Maybe they weakened the sieve box when they put in the jet stream fan and the larger clean grain auger.

pics will follow
20210204_111921.jpg
 

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Have you ever replaced the rubber hanger bushings and bearings before this failure? If any of these get loose it does not take long to hammer a bunch of things apart. My experience on several different brands of combines was that I should have changed the rubber bushings at 1500 thresher hours. It is important when tightening the rubber bushings that the stroke of the sieve be at mid point or the rubber fails much premature. That could be a reason for failure of one side and not the other.
 

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I also had mine go in my non jetstream 570 r because of failed bushings . There was none available so we welded and reinforced it . It has about 300 thresh hours on it since and seems to be holding up fine .
 

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Discussion Starter #6
I also had mine go in my non jetstream 570 r because of failed bushings . There was none available so we welded and reinforced it . It has about 300 thresh hours on it since and seems to be holding up fine .
the lower bushing was just showing cracks. The big one in the center was bad, the inner sleeve was loose. unfortunately in order to check that bushing the toolbox needs to be swiveled out and the reinforcement U channel must be taken of in front of the bushing otherwise you cannot inspect it. The box in the 770 was to much damaged to be repaired it is fubar. Did you put a reinforcement plate into the inside of the box? that is a thought I am pondering. it saves us from taking the box out.
 

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Discussion Starter #7
Have you ever replaced the rubber hanger bushings and bearings before this failure? If any of these get loose it does not take long to hammer a bunch of things apart. My experience on several different brands of combines was that I should have changed the rubber bushings at 1500 thresher hours. It is important when tightening the rubber bushings that the stroke of the sieve be at mid point or the rubber fails much premature. That could be a reason for failure of one side and not the other.
 

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Discussion Starter #8
I agree on centering the bushings, maybe a different solution instead of rubber bushing would help. There is a lot of flex load on these bushings, just try to turn the pulley with the belt loose. Iirc I had a MF 760 and it just a big bearing instead of a rubber bushing. The bushings on the 760 are not bad yet, just a hairline crack and the box has already a fatigue crack (1500 hrs). And the 770 has all new bushings now.
 

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How does a guy check the sieve bushings to see if they need to be replaced? Our 590 has around 1500 seperator hours and we have never touched them. Does anyone know how long they usually go for?
 

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How does a guy check the sieve bushings to see if they need to be replaced? Our 590 has around 1500 seperator hours and we have never touched them. Does anyone know how long they usually go for?
Right now . My right side went at 1500 a couple of years ( 300 hours ) before the left . And yes mine was in 2 pieces so we put reinforcing inside drilled holes and plug welded in addition to grooving and welding the breaks .
 

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Discussion Starter #11
1500hrs seems like the life expectancy of these bushings.
At least check em for cracks. If cracks are visible replace them.
 

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Yep 1500 is in that ballpark where they should just be changed out. Make sure to tighten the bolts at the half way mark on the sieve motion so they are flexing an equal amount in each direction.
 

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Does a guy have to pull the sieves to see the cracks?
No, just walk around the machine and look at the black bushings. I would say the larger the bushing, the more important it is. You can take a pick or screwdriver and somewhat push in on them to see how they feel, or how deep a crack might be.
 

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No, just walk around the machine and look at the black bushings. I would say the larger the bushing, the more important it is. You can take a pick or screwdriver and somewhat push in on them to see how they feel, or how deep a crack might be.
It not a bad job to do Dave. The one behind the tool box is the worst
 

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How does a guy check the sieve bushings to see if they need to be replaced? Our 590 has around 1500 seperator hours and we have never touched them. Does anyone know how long they usually go for?
The first one went at 1540 on my 480. It was a big rubber bushing on the left side that I was able to replace in a couple of hours because I had a couple of spares. The machine ran for a few more hours till finished for the season and then we changed them all in the winter.
 

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When we bought our 585 at 18xx separator hours the seive box was brazed up over the cut out all the way across.
And the left side shows signs of a catastrophic failure, the slot in the side of the combine was hammered out.
Assuming everything must have been changed at that time, since all bushings look good.
How miserable are the bushings to extract? Had to change some on the 8460's, and they were nearly impossible to get a hold of, or to pull out. Is there a tool for the job?
 

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Discussion Starter #18
When we bought our 585 at 18xx separator hours the seive box was brazed up over the cut out all the way across.
And the left side shows signs of a catastrophic failure, the slot in the side of the combine was hammered out.
Assuming everything must have been changed at that time, since all bushings look good.
How miserable are the bushings to extract? Had to change some on the 8460's, and they were nearly impossible to get a hold of, or to pull out. Is there a tool for the job?
you have to take the arms out and use a hydraulic press to push the old ones out and the new ones in.
 

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M57 I was wondering if you could see any cracks from the sheet metal cut out on the outside wall of the combine? I took a look at it tonight. The bushings from the outside looked good and where the sheet metal cutouts were there were no signs of cracks. Is there somewhere else I should be looking?
 

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Discussion Starter #20
M57 I was wondering if you could see any cracks from the sheet metal cut out on the outside wall of the combine? I took a look at it tonight. The bushings from the outside looked good and where the sheet metal cutouts were there were no signs of cracks. Is there somewhere else I should be looking?
Itis almost impossible to see the outside crack, unless you have an endoscope and feed in through the rubber flap from the inside of the combine. you need to take the sieves out to be able to see it, the crack is visible then. After we took the whole sieve box out we were able to see the whole damage, it might have been fixable but we had already a new one ordered. on the old box was almost everything broken except for the right side and one wind deflector sheet. Even two of the four cross mounted sheets are damaged.
But again to make a good assessment you need to take all sieves out and have a good look and good lighting helps too, I hang a cheap 4 foot led shop light from peavy mart under the return pan of the rotors which helped a lot doing the necessary wrenching.
 
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