7720 cylinder bars

How high are the fins in the bars when new. Ours are between 1/4 and 3/8 inch high. Maybe a bit more. Looking at whether to replace them and the concaves at the same time or just cylinder bars. I'm thinking they should go in at the same time for best results.
Also is there a gage for the clearance on the backside when replacing concaves. I know the 9600's had one for them.

Look at the outer edges of the bar...they wear way less on the edge and will give some idea how much is worn-off the center. Can go to the dealership and look at some new bars

As far as adjusting the concave...depending on what crops your after...like around here wheat/Rye...maybe some milo and beans...I adjust the back until it just ticks with the concave adjusted all the way up. Not much you can adjust at the front of a 7720 concave...just level it left to right.

The 7720 only has clearance checking covers at the front. The 9600 has front and rear clearance check points and do use a gauge(a chunk of key-stock will work).

Resist the temptation to buy cheap cylinder bars...like non-chrome black bars. They wear fast...they are cheaper than chrome bars...but by the time you figure labor and hardware to install the cheap bars the longer lasting chrome bars will pay for themselves.

Thanks Ragnarok: I have looked at the ends in the machine when we were looking at things, and seemed to be pretty much the same all the way across. The reason I was asking is it seemed to not thresh quite as good as it did a couple of years ago. Splitting beans more and cracking corn some. We did find the piece with the ring for the cam adjusting screw inside under the concaves was broke. We could not get the square shaft out so welded it in the machine then ground it down to put the pin back in it. Think it got broke with a stone going in during beans.
Is there a way to see the concaves without taking them out from the walkers by crawling in with a light? Would like to see if there is either a hole in the wires or bent in the back.

Hmmm...should be able to get a fair visual on the concave itself by taking the two shields/covers off at the top of the feeder-house. The vertical one has two spring-loaded latches and the other one has a lever on either side of the feeder-house.

There is no doubt that new bars and concave will improve cleaning effeciency...however if the bars are not just shot and the concave worn smooth-out...then adjusting the rear of the concave fairly tight to the cylinder bars(with concave in full up position) will often vastly improve cleaning/threshing effeciency.

I would level the front of the concave and adjust the back until its just 'ticking' the cylinder bars. You can either back it off a bit on the adjustment..or just crank the concave back down a bit so it's not hitting. The concave adjusts wider for beans anyhow.

The concave itself removes and installs from the front with the feeder-house removed. I made an attachment for my cherry-picker to handle the heavy concave. Also it's much easier to install new cylinder bars with the feederhouse removed.

As far as cracking grain/beans..usually that's because the cylinder speed is too fast and or the concave needs opened up some more.

I would start by re-adjusting the concave to minimum and the indicator on the side to zero...then reset everything to whatever specs the destruction manual recommends for whichever crop

The best way to truly check the cylinder bars and concave is to remove the stone trap and then check them both with a straight edge. IF you hit the concave hard enough to break the cross adjustment bar I would bet that the concave is bent.

You should have had the stone trap/lower hinge (9) out when you repaired the adjustment cross shaft. You will need the feeder house raised completely up and install the safety latch. You remove the bolts on each end that go through the side of the combine. Then it will come out the front. Open the concave all the way. With the stone trap removed and the concave wide open you can easily check the front concave bars for wear and straightness. You can also easily see the cylinder bars. Once again lay the straight edge across them. If the middle is much over a 1/4 an inch low you going to have trouble adjusting it to where your not cracking the grain.

You remove the feeder house and replace the concave and cylinder bars from the front. The rear of the concave is adjustable as well as the front. You only have the side gauge holes on the sides. I usually remove the two side panels and reach in the back and measure for the rear level.

IF your planning on keeping the machine for a long time I would install both the concave and cylinder bars using good quality ones. The chrome cylinder bars are worth the extra cost if you run many soybeans.

Not sure where you live but I have a concave out of my old 7700 that was almost new when I scrapped the machine. The bad thing is it set outside for the last 15 years, you can have it. On my 7720 I run the rebuilt bars that are hard surfaced and the fins are a lot taller than OEM. I can start running beans earlier and stay in field longer then with the factory bars in my 9500,but they grind wet corn bad. I remember the Deere combine factory rep telling me about flat bar for corn only but never seen them.

Didn't break the cross bar. Broke the piece that fits under the front end of the concave that is adjusted with the square shaft across there. It has a large round hole to fit on the cam to move the concave up and down with the worm. There is a pin with a cotter pin through it to hold it in the loop on the right or left end of the concave. When we held something don't remember just what, they looked straight at that time. The bars were about a 1/4-3/8 above the wires in the concave just smooth and flat on top.

Buy an enclosed cylinder from Precision Farm Parts. I' know people who ran them and it makes it a whole different machine. It's a high inertia cylinder.