I am getting ready to buy a combine and was wondering how much difference there was between a 7720 and 8820 in capacity and performance, and any other major differences.
Yes, the 8820 is bigger, but to me the problem with the 8820 is that it did not have enough fan. I just could not crank up enough wind on the 8820.
The 7720, on the other hand, is one of the most "balanced" combines that John Deere ever manufactured.
What kind of crops are you going to harvest? Personally, it would kind of be a tough choice for me...ultimately determined by what crops were gonna go through it.
I know most people would opt for the 8820, but I really do love the 7720 (also).
Which way are you leaning? Are both machines available to you for purchase? If so, is one machine a lot cleaner than the other?
Would have to agree with TxFarmer. The 7720 was one of the best combines Deere ever built and I thought the 8820 was one of the most overated combines they have ever built. The cleaning fan had issues on all 20 series. We had problems with concaves bowing on the 8820's. I would probably go with the cleanest lowest houred model.
That's a great point, TXFarmer. It seems manufacturers sometimes take a particular combine frame, boost HP or add a bigger engine, and completely throw off the "balance" of a machine. It's just my opinion but separating and cleaning capacity, grain tank size, horsepower and fuel consumption, are all symbiotic, and ideally, should be kept in a complimentary balance.
Everybody (well, not everybody, but you hear it alot on this forum) says a 7720 was or is a perfectly balanced machine. What makes it so? Why is the 7720 perfect and an 8820 not, the 8820 is 10 inches wider, has more horsepower and a bigger bin, or a 6620 is 12 inches narrower with less horsepower and a smaller bin.
I am just curious why the sayers say the 7720 is perfect or most balanced. This thead is the first time I heard about the 8820 fan, but that did not stop farmers from buying and using them.
The John Deere walkers are not a case where the same machine (spec wise) just gets more horsepower for the different models. That happens with the rotaries (Case, Gleaner, MF and John Deere). So what is the balance issue with the walkers?
I agree with tractor, when it comes to walkers you get a "true" size to go along with more HP and other features. Unlike today 1 size fits all, if you would say.
I have driven a '79 6620, an '84 7720, and 2 different '87 8820's.
The 6620 was bought new and we ran it until '03. We had a 20' flex on it and it was all that it wanted. Good overall combine but final drives were the weakest problem even when we were running a 4 row wide and a 6 row narrow. Didn't have enough power to my liking. Always seemed to choke down which I hated. Though it was way better than the 6600 that it replaced, by far.
My uncle has the 7720. I drove it quite a few times and really liked it better than the 66. Drove better and handled the 24' flex fine. He runs the same 6 row narrow on it and it could handle another 2 rows without a problem. It had been well cared for by the previous owners and it ran like new when my uncle first got it. I believe it barely has over 3000 hours on it now. If both the 66 and 77 were in the field at the same time, I was trying to get behind the wheel of the 77. It's that much better. IMO.
We now have an 8820 Titan 2. I started out on the 66 first, then drove a 77, and then finally in the 88 and I am going to tell you,....... there's NO WAY that I would go backwards. The capacity, the power, the way it drives (especially now with the duals) is just uncomparable. They are all in essence the same, but with the 88 you get that much more of a machine and haven't had a minutes trouble out of it since we got it back in the summer of '03. It handles the 25' flex easily and could take a 30' without any problems. The 6 row narrow was WAY too small for it. It wasn't loading the machine at all. Now we have an 843 and it still has no problems with it. It could handle a 12 row without a doubt. The final drives are planetaries with axle spacers and the axle is so much bigger than the 66 we had.
When we got this 88 back in '03, we teamed it with the 66, side by side. My granddad in the 66 and me in the 88. That thing was broke down all the time that fall. It was irritating to my granddad. He was trying to keep up with the 88 and he just couldn't. So what does he do? He goes out and buys himself an 88 in Jan of '04. Another '87 model like ours(mine and dads).
My granddad always said that the 88 was too big for our operation, thats why they (him and my dad) bought a 6620 back in '79. And after all those years, he saw first hand that the 88 was one helluva machine and bought one himself. Just wish that he and that combine were still around.
I know a few guys runs 7720s in my area. And they really love theirs. It just depends on your farm size. Plus if you look at it. The 8820 isn't really much bigger than the 7720. So either way you can't go wrong with it.
I've heard that too and I have yet to see anybody offer any facts or evidence to back that up.
At one time JD offered a 9760/9860. That was the same all around, but HP was the main difference. They kinda fixed it when the 70 Series came out. Now you have the CIH 8120/9120, only thing there is HP. The rest of the stats are the same. And the NH counterpart of that size is like that too. That is how you get 1 size fits all. Just cram a more HP engine in it. And call it a bigger combine. HP increases don't make a combine bigger.
I would be more than happy to throw up the chart. To confirm a one size fits all. But that is not part of this topic. Where the topic is about 7720/8820 combines.
I've heard that too and I have yet to see anybody offer any facts or evidence to back that up.
Guys, I'm not sure who's post you are referring to. If it is mine, you need to go back and re-read what I said. I have never said the 7720 is "perfect". I said it was more balanced (relative to no. of walkers vs capacity of fan, etc), and that is still my opinon. I never said anything about power, grain tank, blah blah blah. In my opinion, Deere should have given the 8820 more fan...and yeah, it is easy for me to say that looking backwards (I realize this). That is my whole point why it is my opinion that the 7720 is more balanced. Never said the 8820 was bad..geez, why must someone provide "facts" to state an opinion?
I simply stated that the 7720 is a well balanced machine. Period. End of story...
TxFarmer and Houser made the best points, already. Tx, I never read anywhere, that you implied any negativity toward the 8820, either. I have run both, worked on both and can testify to exactly what Houser stated. The internal component structure, skin and even framework of both are the same weight, guage, thickness, etc. The spans for the 8820 are greater, and therefore should have been thicker, heaver, more gusseted and such. This is where manufactures always fail to compensate, period. As for fan capacity, that really depends more on the crop. I've never seen a significant "shortage" of fan cap in an 8820, as opposed to a 7720.
For comparison purposes, the 860, 8820 and 1680 would be apples and apples as they were the largest or most powerful models built by MF, JD and IH at that time. In clean, dry wheat, the 1680 rotor would be close with the 860 and 8820 walkers. In tougher conditions, higher moisture and weeds, the walkers would most of the time beat that rotor.
The 1660 would be closer to your 7700 in capacity, as a 7720 would have been its size counterpart. What do you want? A lot more capacity in varying conditions (the 860), or a machine for cutting mostly clean dry wheat that is about the same capacity/productivity (in reality a little more) than your 7700 (the 1660).
You may find this interesting.
All the machines you mentioned have been tested: http://www1.agric.gov.ab.ca/$department/....pendocument#531
Click on Evaluation Report for full test.
Note some machines tested beside Reference combine, some beside Reference II.
Reference is a JD 6600, Reference II is a JD 7720 Titan II.
A 1.5 to 1.7 times spread between those two.
Wow, that sure shoots down my false impression that an 860 was close to an 8820 when both are compared to the 6600 in the test conditions. It also looks like, in the test condtitions, the 1660 and 1680 were equal to or more than the 8820.
Off subject I know but would appreciate input as I'm considering replacing my 7700. Decision is between a MF 860, CIH1660 for wheat. Some claim that the 860 will perform alongside the 8820. Some claim the CIH 1660 or 1680 will perform as well as the 8820. Fact or just fiction?
Thanks for input since I have little or no experience in this comparison.
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Jens Haslund-Thomsen · updated 
